INTRODUCTION to the WORKSHOP Dr. G. Ortega 2021, May 11th
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
INTRODUCTION to the WORKSHOP
Dr. G. Ortega
2021, May 11th
ESA UNCLASSIFIED - For Official Use
1
…the process of technology
1 I have a great idea!
2 I write a proposal
3 My proposal is approved
4 I execute the activity of the proposal
2
Welcome !
•Original idea of the TEC-MPA
Section of ESA and materialized
in 2021
•Is there any interest on Will the idea of the
pre-discussions
discussion ideas for technology
work?
prior we make any kind of
proposal?
•Number of registrations: 161
3
Objectives
• Objective 1: Provide for an
overview of the current state of
technology ideas
• Objective 2: Gather inputs from
possible Bidders
• Objective 3: Prioritize the
upcoming research and
development inputs to the ESA
technology plans (TRP, GSTP) for
the coming cycle
4
Scope of the Workshop
• 1) Technology for the architecture design, analysis and technical
assessment of space transportation vehicles for suborbital, orbital and
exploration applications, including upper stages, (re)-entry,
expendable, and reusable vehicles
• 2) Technology for the development of tools and techniques for the
feasibility and viability assessments, and quick design iterations of flight
vehicles
• 3) Technology for flight vehicles, flight physics, aerodynamics,
thermodynamics and fluid dynamics engineering and the
architecture design and analysis of suborbital, (re-)entry, space
transportation, and exploration vehicles
5
Time Line
1 2 3 4 5
May June September October November
Workshop Consolidation of Final list of the best Preparation of Introduction of the
ideas ideas (including upcoming TDE ideas in ESA
description) cycle internal system
6
The program
7
Can I take your idea and ….?
•No, please
•The ideas are provided to you with the aim of
discussion
•The information should not be used to move the
ideas to non-ESA technology programs
8
I have another idea…
•Can I please discuss with you privately?
•Yes, of course. No problem. See points of
contact
9
ESA points of contact
Csaba Jeroen Johan Luca
Louis Orr Richard Stephan Victor
10Thank you to the organizers!
Csaba
Orr Stephan
11Have a great
Workshop!
ESA UNCLASSIFIED - For Official Use
12Day 1
13Prediction Fluid Dynamics Methods for Propellant Tanks
Prog. GSTP Budget: 800K Duration: 24 months Aim: A Ref.: A 04 TRL: 4 to 5
Objective(s):
To develop prediction methods for cryogenic multi-phase flows to application level and provide experimental data from breadboard, on
ground micro gravity facilities and flight experiments that can be utilized to validate such methods. Quantification of margins of
uncertainty for experimental and numerical data shall be investigated, in detail.
Description
Numerical techniques are developed and validated in a structured manner for the different relevant environments from ground
conditions to micro gravity and isothermal single phase applications to non-isothermal with phase changes.
Incremental validation is applied, i.e. all new levels of modelling have to demonstrate that all lower levels of required modelling and
complexity can still be treated successfully.
Resulting CFD tools are required to be computationally efficient, empirical models shall be proposed to avoid excessive computational
effort for flow accurate prediction of phenomena that require very high temporal spatial resolution of the applied CFD method.
Quantifiable margins of uncertainty as consequence of incomplete modelling have to be accepted to allow calculation of flow
configurations that are typical for todays applications.
Background and previous activities
Long history of CFD development and related validation testing.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
14Interaction of Fluid and Structures under Sloshing Conditions
Prog. GSTP Budget 800K Duration: 24 months Aim: A Ref.: A 05 TRL: 4 to 5
Objective(s)
This activity shall assess functionality of FSI methods for the prediction of fluid motion and structure response, resulting forces on
structures and effect on space craft trajectory and attitude. Storable propellants, commonly used in satellites and cryogenic propellants
used on launch vehicles shall be considered. Material characteristics of tanks and support frames shall be analyzed for cryogenic
applications. To prepare refueling of cryogenic tanks in orbit, also flow kinematics of valves, bubble pressure grids and vanes shall be
investigated.
Description
Sloshing creates forces on structure elements that are transmitted to the spacecraft. Such forces have an effect on spacecraft
dynamics and have to be known by the GNC system to provide commands to attitude control systems to keep the spacecraft in a
stable and controlled condition.
Material properties, including materials that might show advantages for the specific requirements of fuel reservoirs in orbit shall be
investigated in detail, considering also cryogenic conditions.
Membranes as PMD for storable propellants allow extended exposure time to fuel, similar improvement for oxidizers are in progress.
Utilization of membranes that separate fluid and gas content of a tank are therefore promising, since the complex multi-phase flow
fields of free surface tanks, are avoided. The contractor shall assess, if present FSI methods, based on available material data of
image
membranes, can reliably predict topology of membrane and kinematics of the fuel, forces on membrane and structures.
Missing material data shall be identified and reported.
Finally, a detailed analysis of the resulting margins of uncertainty for the coupled FSI result shall be provided. The contractor shall
propose means to reduce the margins by improved modelling of liquid motion and / or structural response.
Background and previous activities
Prediction of sloshing motion in tanks can be predicted well for large gravity.
For capillary flows with small Bond numbers, surface tension and contact angles are presently not known already for ideal liquids,
certainly not for cryogenic conditions. Numerically efficient solution methods, e.g. solving Navier Stokes equations for the kinematics
of a fluid mass in a tank that is exposed to external acceleration require empirical data for contact angle and interface models that are
presently not available for cryogenic liquids in micro gravity.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
15Toolset for the Design of Cryogenic Systems
Prog. TDE Budget 500K Duration: 24 months Aim: A Ref.: A 07 TRL: 2 to 3
Objective(s)
Development and validation of tools for cryogenic systems, e.g. a cryogenic reservoir in orbit. Exiting tools, e.g. boil-off tools shall be
critically reviewed, margins shall be identified and related to margins acceptable for design.
Tools shall be updated by introduction of more accurate modelling methods and the result on the overall prediction error shall be
estimated.
Description
An existing and published integral tool, here for boil-off in a LH2 or methane reservoir in orbit shall be systematically checked for
short-comings and updated to a level that allows application to complex cryogenic systems. Updates can include replacing empirical
models, e.g. for heat transfer between liquid fuel and tank structures by more detailed CFD rebuilding, if justified and affordable.
The dependency of prediction accuracy on time and particular nodal representation (e.g. number and arrangement of nodes) shall be
quantified.
Thorough validation of tool performance and accurate estimation of remaining margins of uncertainty is considered a pre-requisite for
successful tool application and is therefore considered the most important outcome of this activity.
image
Background and previous activities
Presently, validated tools for design of complex cryogenic systems do not exist, but simplified tools, as the present boil-off tool are
frequently used for optimization tasks. Tool application to design requires detailed knowledge on tool accuracy.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
16Material Point Method for Sloshing and Multiphase Flows
Prog. GSTP Budget 300K Duration: 18 months Aim: A Ref.: A 11 TRL: 4 to 5
Objective(s)
Review, improve and document functionality, including accuracy, computational efficiency and robustness of dual
Eulerian and Lagrangian CFD methods for the description of multi-phase flows.
Description:
Presently, multi-phase flows are predicted with numerical schemes that solve for conservation of mass, momentum
and energy with added empirical models for physical aspects of the solution that are not covered by conservation
properties. In this activity conservation schemes (Eulerian description) and particle methods (Lagrange description)
are combined in one numerical method that is not dependent on, often difficult to obtain, empirical models or data
for missing physics. This activity shall review existing dual schemes, particularly MPM and SPH schemes for their
image
ability to rebuild complex multi-phase flows, propose and introduce scheme updates and demonstrate functionality
as cost, accuracy and robustness of such advanced schemes, if compared to Navier Stokes and empirical
modelling.
Background and previous activities
Accurate description of even physically simple, i.e. isothermal multi-phase flows is still a challenge for conservation
schemes, e.g. the Navier Stokes equations. Advanced numerical methods that include all physics required to rebuild
the flow field and, simultaneously the free interface topology in the flow field without the need for additional
empirical data from experiments are systematically examined for their potential to improve prediction accuracy/cost
for such methods.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
17Improved Ullage Bubble Dynamics Model
Prog. GSTP Budget 300K Duration: 18 months Aim: A Ref.: A 19 TRL: 4 to 5
Objective(s)
To improve physical models for ullage dynamics in micro or zero gravity for storable and cryogenic applications, to
allow predictions of effects of ullage bubble relocation in the tank on spacecraft dynamics as input to a GNC system.
Description
Prediction of kinematics of an ullage bubble in a tank in micro gravity is still a challenge. Since conservation
equations for mass, momentum and energy do not contain information on molecular physics that are responsible
for the, in micro gravity, dominant surface tension and contact angle effects on liquid and IF movement, empirical
data has to be provided as boundary condition for the Navier Stokes equations. Particularly for cryogenic
applications, such empirical data is today still not available in a generally usable and validated form.
Resolution of all physical influences that determine bubble dynamics for cryogenic multi phase flows is still not at
hand and will not be available anytime soon.
A central part of this activity is therefore the quantification of expected solution accuracy for different methods with
different complexity and costs, allowing to propose the most economical solutions methods that meets the accuracy
image
requirements, coming from design.
Background and previous activities
Kinematics and dynamics of ullage bubbles is still not fully understood. Some progress has been made in recent
years leading to the conclusion that dynamics of ullage bubbles in zero gravity cannot be predicted from linear
dynamic models. Improved modelling is therefore required, selecting the most economical method that still
considers physics sufficiently well to allow to predict the most characteristic features of sloshing in micro gravity
and its effect on space craft dynamics.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
18Development of an Experiment for Transient Phase Change
Aspects in Microgravity for Cryogenic media
Prog.GSTP Budget 600K Duration:24 months Aim:B Ref.:B 02 TRL: 4 to 5
Objective(s)t
This activity shall assess the status of experiments for transient phase change phenomena of cryogenic liquids in
micro gravity. It shall identify and collect existing data and justify, plan, design and conduct experiments to
supplement presently still missing data. Experiments shall be designed as breadboard, for existing micro gravity
platforms, parabolic flight campaign or ISS, as needed and if justified. The contractor shall investigate in detail, in
how far breadboard experiments can be used to obtain the required data for cryogenic liquids in micro gravity.
Description
Phase change of cryogenic fluids in micro gravity, particularly for capillary flow conditions, is still not reliably
predictable by available CFD methods. This is mainly due to unavailability of experimental data recorded under
conditions that are sufficiently similar to flight. Such data is required to build and update physical models in CFD
tools for phenomena that are not covered by the physics that is resolved by CFD method, e.g. molecular dynamics
determining interface topology in multi-phase flow problems, which is not accounted for by mass, momentum and
energy conservation as described by Navier Stokes equations. For cryogenic liquids, transient phase change
phenomena for different time scales are responsible for many aspects of flow development. Due to the non-linearity
image
of the physical effects involved, even short duration transient phenomena can determine the flow development.
Identification of such short term multi-phase phenomena that have a strong impact on the overall flow development,
e.g. effects of the Leidenfrost effect on bubble attachment versus bubble rejection by a heated wall structure is of
prime importance.
Background and previous activities
Experimental data for phase change phenomena of cryogenic liquids in micro gravity is not available with an
accuracy that would allow to use experimental data to build physical models for the consideration of such
phenomena in CFD rebuilding.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
19Spacecraft Re-fuelling Ground Testing
Prog.GSTP Budget 1.2M Duration:24 months Aim:B Ref.:B 05 TRL: 4 to 5
Objective(s)
This activity shall perform ground testing for spacecraft refueling. Testing shall focus on elements that can be
justified to the sufficiently independent from the test environment, as mechanisms for docking and undocking, leak
tight fuel line connection and disconnection with minimal risk of contamination of instruments on the receiving
spacecraft.
Description
Spacecraft refueling in LEO or GEO is presently considered a promising solution to allow for exploration missions
beyond the moon. A reservoir for cryogenic fuels shall be placed in orbit, allowing spacecraft launched from the
earth surface to replace fuel that has been consumed to escape earth gravity and extending their range of operation
in orbit, substantially.
Whereas some functionalities of a refueling device can only be tested in a relevant micro gravity environment, a
number of tests can be performed in gravity, i.e. technology and operations required to dock spacecraft to
reservoirs, to connect and test fuel lines and connectors for leaks, to disconnect fuel lines with minimal loss of fuel
image
to mitigate the risk of contamination of sensitive instruments, etc.
The contractor shall identify testing that can be performed on ground and justify the test by thorough analysis of the
governing similarity rules. For feasible tests he shall design a test facility, using available elements, sensors,
robotics and mechanisms, as much as possible. Tests shall then be conducted, in line with the available budget.
Recommendation for additionally required testing shall be provided.
Background and previous activities
Spacecraft refueling has been routinely performed for storable propellants and consumables, e.g. to allow ISS
extended operation in orbit. The present activity shall utilize the findings from such developments and assess,
which additional requirements have to be met to extend fueling activities to cryogenic fuels and refueling of
spacecraft from a LH2 or methane reservoir in orbit.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
20Instrumentation for Cryogenics Propellant Tanks
Prog.GSTP Budget1.5M Duration:24 months Aim:C Ref.:C 03 TRL: 4 to 5
Objectives:
This activity shall assess the status of instrumentation for cryogenic tanks, select the best technical solution for
each instrumentation option, justify the choice and recommend additional elements that might be needed for new
applications.
Description
Conventional cryogenic propellant tanks need to be instrumented to allow for fuel gauging and monitoring of tank
functionalities, e.g. control of tank pressure and related boil-off. Instruments have to withstand the rough thermal
conditions in a tank for the entire operational time, i.e. some years for fuel reservoirs in orbit.
The contractor shall assess available instrumentation that is already verified for cryogenic conditions and identify
additionally required hardware to meet the objectives.
Special attention shall be paid to new functionalities, e.g. of tanks that can be re-fueled with cryogenic liquid after
extended operation. Additional requirements and specifications for such hardware, e.g. for shall be identified and
image
reported.
Optical fibers have been identified In breadboard experiments as a means to improve reliability and speed of signal
transmission between sensors and control elements. This hardware shall be assess for its compatibility to flight
conditions, including robustness to withstand the loads acting on sensors and optical fibers or electrical wiring.
Background and previous activities
Instrumentation of cryogenic tanks with sensors and non-intrusive methods has been assessed in detail in the
Cryosense activity /…/. Optical fiber based instruments have been validated for temperatures as low as 20K, some
elements have been demonstrated to work in breadboard experiments in liquid Helium at 3K.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
21Ultrasonic Non-intrusive Measurement Techniques for
Storable and Cryogenic Liquids
Prog.GSTP Budget 300K Duration:18 months Aim: C Ref.:C 04 TRL: 4 to 5
Objective(s)
To extend a recently developed non-intrusive measurement method based on ultrasonic sound fields to cryogenic
conditions.
Description
Non-intrusive measurement techniques are an important means to gain information on the condition of fuels in
tanks during spacecraft operation. Particularly for cryogenic liquids penetration of the tank structure for cables or
optical fibers can increase the complexity of a tank design, considerably and will increase undesired heat transfer
into tanks. Accurate gauging allows efficient use of fuel during a mission.
Non-intrusive measurement techniques, e.g. by means of transmission, reception and analysis of ultrasonic sound
fields have been demonstrated to work under breadboard conditions for storable propellants. This development
shall be extended, to allow for ultrasonic diagnostics also for cryogenic liquids.
The contractor shall investigate in detail, if the technology can be applied also without tank penetration and on image
already space qualified tanks.
The measurement equipment that radiates, records and analyses the sound field shall be redesigned to allow for
cryogenic temperatures. The contractor shall investigate, if non-penetrating mounding of transmitters and sensors
is already feasible.
If that is the case work shall be focused on developing the measurement equipment in terms of size, weight and
implementation requirements to a level that allows to integrate it on existing space craft, If non-penetrating
mounting is shown to deteriorate the quality of the measured data, focus of this activity shall be to improve the
experimental hardware in this respect and to improve the design of cryogenic tanks to mitigate the effects of non-
penetrating mounting.
Background and previous activities
Non intrusive measurement methods based on transmission, recording and analysis of ultrasonic sound fields into Breadboard set-up from Cryosense
a tank have been developed and demonstrated for breadboard applications and non-cryogenic conditions in /…/.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
22Consistent prediction of liquid/gas interfaces in micro gravity Prog. GSTP Budget 500K Duration: 24 months Aim: A Ref.: New 01 TRL: 2 to 4 Objective(s) This activity shall investigate the limits of efficient numerical schemes, e.g. Navier Stokes equations for the prediction of capillary flow phenomena and propose strategies to mitigate the short comings to extend the validity to more and more capillary flow conditions. Description Liquid/gas interfaces in micro gravity are determined by capillary mechanisms. Correct prediction of IF topology is a pre-requisite for CFD rebuilding of technically relevant flow phenomena, e.g. heating and related boil-off of cryogenic fuels in tanks and reservoirs, impact of sloshing on CoG, impact of slosh damping on pointing accuracy of exploration and telecommunication satellites, etc.. Whereas for high gravity and Bond numbers, empirical models that describe the pressure jump normal to an IF are sufficiently accurate to predict realistic interface dynamics, for small Bond numbers (Bo
Uncertainty quantification for cryogenic flow modelling in
micro gravity.
Prog. TDE Budget 400K Duration: 18 months Aim: A Ref.: New 02 TRL: 2 to 4
Objective(s)
Quantification of approximation error for CFD predictions for cryogenic flow problems in micro gravity including
effects of required empirical models.
Flow rebuilding with CFD methods contains an approximation error that depends on chosen discretization of the
spatial and temporal scales of the problem. If solutions are entirely determined by conservation principles, e.g. for
mass momentum and energy as for the Navier Stokes equations, reliable methods are available to characterize the
prediction error and reduce it, if required by optimization of the prediction set-up to any desired value.
In case the solution is significantly influenced by empirical models, e.g. for flow features that are not covered by
conservation principles, the total prediction error also depends on the quality of empirical data. For such more
complex systems, a method shall be developed that allows to quantify overall prediction errors, including effects of
empirical modelling or unavoidable model inconsistencies of existing CFD methods.
Based on such findings that contractor shall provide means that allow to select simulation parameters as spatial and
temporal resolution and, e.g. required accuracy of empirical input data to guarantee a pre-defined error margin on
data of technical interest.
Background and previous activities
CFD methods for multi-phase applications, even for isothermal and incompressible liquid/gas problems, are still
suffering from not well understood margins of accuracy, due to utilization of empirical models. For cryogenic
applications margins of experimentally recorded empirical data are generally enlarged and can accumulate.
Particularly for such applications, error margins for results of technical interest should be available before start of
the simulation.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
24CFD and breadboard testing for empirical data for non-
isothermal applications
Prog. TDE Budget 300K Duration:18 months Aim: A Ref.: New 03 TRL: 2 to 3
Objective(s)
To extend an existing breadboard test facility to include investigation of non-isothermal tow phase flow problems.
Description
In this activity the domain of application of a breadboard experiment that allows to record relevant flow data for
applications in micro gravity shall be extended to non-isothermal single phase flow problems. Existing hardware
shall be adapted, allowing, e.g. to accurately prescribe surface temperatures independent from the temperature of
the liquid.
Temperatures shall be electronically controlled, provisions to keep the liquid temperatures constant over time, shall
be investigated, if necessary.
A CFD method shall be selected that has been, at least, partially validated for the prediction of heat transfer in
image
incompressible two phase flows. The method shall be validated in detail for accuracy of heat transfer predictions.
The validated method shall then be utilized to predict experimental results using existing empirical models for static
and dynamic contact angles and hysteresis, the deviation of measured and predicted flow parameters shall then be
used to optimize and fine-tune empirical CA models using available System Identification (SI) methods and tools.
Background and previous activities
A breadboard test facility has been assembled at ESTEC that allows to quantify the effect of physical mechanisms
that are normally only visible in micro gravity also in ground experiments. Proof of concept has been demonstrated
for isothermal flows, however, the method is as well applicable to multi-physics application, e.g. including non-
isothermal effects on the flow field.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
25Acoustic manipulation methods for cryogenic flows
Prog. TDE Budget 600k Duration:24 months Aim: B Ref.:New 04 TRL 2 to 3
Objective(s)
This activity shall extend the range of application for a novel technique that can move fluid and gas by means of
ultrasonic sound fields from an array of piezo electric transducers. It shall check and confirm the robustness of
hardware in cryogenic conditions and demonstrate this promising flow control method for cryogenic applications, in
a breadboard environment.
Description
Based on available promising results for isothermal applications, the technique shall be extended to cryogenic
conditions for application to existing cryogenic launcher U/S, orbital reservoirs and refueling of spacecraft in orbit.
For cryogenic application, heat intake into the tank requires complex and expensive cooling or boil-off of fuel
Therefore the method has to be carefully designed to limit heat intake to a level that can be justified by the benefit of
the fluid manipulation method.
image: (current
Background and previous activities
Acoustic manipulation techniques have been demonstrated to efficiently move isothermal liquid and ullage bubbles
in bread board experiments, mitigating potential risks of bubble ingestion in fuel lines to the engine.
Based on available promising results for isothermal applications, the technique shall be extended to cryogenic
conditions for application to existing cryogenic launcher U/S, orbital reservoirs and refueling of spacecraft in orbit.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
26Cryogenic aspects of refuelling
Prog.TDE Budget 500K Duration:24 months Aim: A Ref.:New 05 TRL: 2 to 3
Objective(s)
This activity shall extend the technologies developed for refueling of storable propellants in orbit to cryogenic
liquids.
Description
Assessment of presently available engine technology in the context of Tsiolkovsky’s rocket equation indicates that
fuel reservoirs in orbit are required for exploration missions beyond the moon. Presently ongoing activities on
prototyping of refueling with storable propellants in LEO and GEO shall be extended to allow operation with
cryogenic liquids. Cryogenic liquids can undergo phase transitions during refueling, that require special attention
since requirements, e.g. for gas free expulsion of liquids from a refueled tank, and venting of tanks during re-filling
still have to be met.
This activity shall investigate, which tools are already available and validated to support the design. Existing
shortcomings shall be identified and related updates shall be proposed and implemented, if consummate with the
available budget.
The contractor is expected to provide detailed recommendations on additionally required development steps and
require future activities.
Background and previous activities
Prototyping of refueling in orbit is ongoing, focusing on applications for storable propellants. New applications are
emerging, e.g. allowing extended exploration missions by refueling of space craft in LEO or GEO.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
27Development of a Non Intrusive Sloshing and Refueling Spacecraft
Demonstrator for Micro-gravity
Prog. TDE Budget 2000K Duration:24 months Aim: D Ref.: D 02 TRL: 2 to 4
Objective(s)
To develop, design and validate a demonstrator for sloshing and refueling in micro gravity with non-intrusive
measurement technology.
Acoustic manipulation techniques have been demonstrated in a breadboard environment for isothermal flow
problems. The technique shall be extended to cryogenic onditions and be demonstrated as a means for, e.g. bubble
removal from cryogenic liquids in micro gravity.
Background and previous activitiesNon-intrusive measurement technology has been developed and validated for
storable propellants in a bread board environment. Currently this activity is extended to allow for flow field
diagnostics also for cryogenic fuels.
The present development shall be demonstrated on a demonstrator flight using sounding rockets.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
28Appendix: Cryogenics in Microgravity
Outline – Needs, status and perspective for future activities
• Brief Assessment of new missions and requirements
• What is now needed ?
• What is already working ?
• What is presently still missing ?
29Appendix: Cryogenics in Microgravity
Example for new requirement:
Fuel reservoir in orbit.
• Large dimensions
• Capillary conditions
• Cryogenic fuels ?
Experiments:
• Full scale flight testing is expected to be cost-prohibitive
• Ground micro g facilities have limited test duration
• Breadboard activities could allow specific micro gravity data at
reduced costs
https://www.energy.gov/sites/prod/files/2014/03/f9/compressed_hydrogen2011_11_chato.pdf
Simplified tools, e.g. boil-off tools:
• Not completely validated: Cross validation between simplified models missing
• Relevant physics is partially excluded to maintain validity of simplified modelling (mixer is assumed to avoid stratification)
• Required modal resolution (number of liquid and structural nodes) for tools is not clear:
…
30Appendix: Cryogenics in Microgravity
CFD methods:
• DNS/DSMC: working and validated but too expensive
• Navier Stokes: requires additionally empirical models for physics that is not resolved by conservation
schemes for isothermal, non-isothermal and non-isothermal with phase transitions :
• surface tension (ST),
• static and dynamic contact angle (CA) and hysteresis
• Consistency issues exist with ST modelling for low Bond numbers
• Dual Eulerian and Lagrangian methods (e.g. MPM and specifically SPH) do not need additional
measurements for empirical modelling of ST and CA, but resulting solution accuracy has not yet
demonstrated clear improvement over Navier Stokes solutions.
31Appendix: Cryogenics in Microgravity
• Conclusions:
• Simplified methods (boil-off models) not mature for design
• Experiments in relevant similarity conditions, particularly requested for empirical data for conservation schemes, i.e.
Navier Stokes, are not expected anytime soon
• CFD suffers from missing empirical data and inconsistent boundary conditions, e.g. for ST in capillary flows
To do:
• Simplified methods (e.g. boil-off tools) have to be matured and validated for complex applications. Methods should be
validated as far as possible, margins of uncertainty have to be quantified and reduced, by replacing over-simplified
modelling by more advanced methods, e.g. CFD tools.
• Breadboard testing should be developed to allow recording of required empirical data with approximated micro gravity
conditions, where possible. Strict requirements shall apply.
Stronger focus on utilization of breadboard testing, as long as margins of uncertainty are understood and CFD is available
and validated (grid and time converged) for the selected set-up
+ Such experiments could be easily extended to multi-physics, e.g. for CA testing in non-isothermal conditions
32Appendix: Cryogenics in Microgravity
• CFD has to be matured, boundary conditions, e.g. for CA and ST
used in multi-phase modelling has to be checked for consistency
• Remaining shortcomings (e.g. for ST formulation) shall be
mitigated, as far as possible
• Flow phenomena that presently cannot be resolved and
predicted with Navier Stokes shall be modelled, e.g. :
• Onset of boiling for non-isothermal liquids in tanks,
• Attachment and detachment of ullage gas and liquid
lumps to tank walls.
• …
33Development and Flight Validation of Multi-physic Tools for
Propulsion Controlled Landing
Prog.GSTP Budget 500 Duration:24 months Aim: D Ref.: D 03 TRL: (current to Target)
Objective(s)
Objective of the present activity is the development and validation of an inter-disciplinary prediction tool that can
take all relevant physical mechanisms during propulsion controlled landing in earth of planetary atmosphere into
account. After validation of the single discipline components of the methodology the tools shall be coupled in a
multi-disciplinary prediction tool that will allow to optimize the design of the hardware for robustness and stability. A
subscale lander shall be assembled from off-the-shelf components. Application of the multi-physical tool to the
subscale demonstrator allows to validate the multi-disciplinary tool and demonstrate the robustness of the
algorithms in flight. This activity will also comprise to input of experimental data"
Description
This activity shall assess the status of multi-physics predictions for descend and landing on planets (including
earth), moon and asteroids. Depending on spacecraft mass, gravity level and atmosphere, propulsion controlled
landing can be required. This activity shall develop and validate a multi-physics tool that can keep track of, at least,
the most important physical effects that have an influence on descend and landing of a spacecraft.
Background and previous activities
Propulsion controlled landing can be required for exploration missions.
Technical Officer: Richard Schwane (Richard.Schwane@esa.int)
34Development of a Flight-back Booster Demonstrator Phase B
Prog. GSTP Budget 3000K Duration:36 months Aim: D Ref.:D 06 TRL: 3 to 5
Objective(s)
Development of a Flight-back Booster Demonstrator
Description
Critical assessment of State-of-the-Art of flight-back-booster technology. Identification of technology gap, risk
assessment.
Background and previous activities k
Continuation off Flight back booster demonstrator development.
The LFBB model used in wind tunnel tests by the German
Technical Officer: Richard Schwane (Richard.Schwane@esa.int) Aerospace Center (DLR)
35Green Propellant Usage
in Long Duration Exploration Missions
TDE 400 k€ Duration: 24 months Aim: A Ref.: - TRL: 3 to 4
Objective(s)
The reduction of stability and storability, because of (adiabatic) decomposition or degradation due to surface reactions, of low-
toxicity/green propellants needs to be characterised in order to use them safely and efficiently in long-duration exploration missions, in
particular crewed missions.
The current basic research activity will improve the understanding of the material compatibility and storability of green propellants,
which will facilitate the selection of propellant and material combinations during mission and spacecraft design.
Description
In the last few years there has been a push to develop low-toxicity, so-called green, propellants (e.g. hydrogen peroxide, ADN-blends,
etc) as replacements for standard hydrazine-based systems. This is in part because of Europe's "Registration Evaluation Authorisation
and Restriction of Chemicals" (REACH), which has put hydrazine on its list of high-concern substances, but also because of the
reduced environmental impact and potentially lower operational cost (due to less health & safety restrictions).
In particular for long-duration missions that include a potential human presence, such as future missions to the Lunar Gateway, the
usage of low-toxic propellants could be highly beneficial. Long-duration exploration missions require highly storable and stable
propellants that can remain safe and effective for several years. The storability and stability of low-toxicity propellants, such as
hydrogen peroxide, is driven primarily by surface decomposition. Experimental testing of these characteristics should therefore be
done for combinations of propellants and surface materials, to allow for the appropriate selection of tank and/or liner materials to be
used with those propellants. Such testing can give rates of propellant degradation/decomposition (or Active Oxygen Loss in the case
of hydrogen peroxide), but high-quality testing data is scarce.
© European Astrotech Ltd
The current activity will include an extensive review of low-toxicity (green) propellants, to identify the driving parameters, risks and
constraints for the selection of such propellants for long-duration exploration missions. In particular, data on propellant
ageing/degradation and (adiabiatic) decomposition will be gathered, and dataset gaps identified. An experimental campaign to test the
decomposition and material compatibility of low-toxicity propellants will be designed and performed, which will allow a more accurate
characterisation of the different propellants and their suitability for long-duration exploration missions.
Background and previous activities
Activity is captured in the Technology Harmonisation Dossier 2020 on ‘Fluid Mechanics and Aerothermodynamic Tools’ (A22)
© European Space Agency
Technical Officer: Jeroen Van den Eynde (jeroen.van.den.eynde@esa.int)
36Post Flight Data Analysis Toolset
GSTP 400 k€ Duration: 12 months Aim: A Ref.: - TRL: 4 to 6
Objective(s)
The objective of the activity is to develop a software tool for level-2 post flight data analysis to support flight reconstruction and
confirmation of flying qualities.
Description
The post-flight data analysis of a flight vehicle is an important element in the assessment of its nominal and/or off-nominal
performance and behaviour. Different levels of post-flight analysis can be performed, depending on the level of detail required and
disciplines involved. A toolset for level-1 post-flight analysis is currently under development, to be released publically as an open-
source code, which deals with the disciplines of propulsion, aerothermodynamics, performance and structures.
The current activity does not envisage to provide an update of this toolset, but rather focus on the development of a more in-depth and
detailed level-2 analysis methodology of the flight vehicle performance. Interfacing the two toolsets could however be foreseen in the
activity.
The level-2 post flight data analysis toolset will be able to provide a detailed flight reconstruction (i.e. obtain the Best Estimated
Trajectory), system identification (i.e. model reconstruction of the dynamic and kinematic behaviour) and confirmation of the flying
qualities (i.e. obtain an accurate mathematical description of the behaviour and vehicle performance).
The activity will entail the design and development of the level-2 analysis methodology, and its validation using flight-data.
Background and previous activities
Activity is captured in the Technology Harmonisation Dossier 2020 on ‘Fluid Mechanics and Aerothermodynamic Tools’ (A27)
A level-1 toolset for post-flight analysis (PFAT) is currently being developed under the ESA TDE programme.
Technical Officer: Jeroen Van den Eynde (jeroen.van.den.eynde@esa.int)
37Gas-Surface Interaction and Soil Erosion
due to Pulsed Jets
GSTP 500 k€ Duration: 18 months Aim: B Ref.: - TRL: 3 to 5
Objective(s)
The goal of the activity is to understand the dynamic gas-surface interaction of pulsed jets impinging on soil underground, characterise
the soil erosion and uplifting, and identifiy their effects on a spacecraft during terminal landing.
Description
With the new interest into the Lunar Gateway and the potential of recurrent ascent/descent operations on the Moon’s surface by
European spacecraft, e.g. European Large Logistics Lander (EL3), an improved understanding of the plume/surface interaction with
granular flows is required. In particular the dynamics of this interaction, the pressure oscillations of the plume flow and resulting soil
behaviour needs to be understood. While it has previously been shown that some elements of the plume/surface interaction can be
simulated using porous media equivalent models (i.e. Darcy’s Law), the erosion and uplifting of the soil requires the modelling of the
granular underground.
The envisaged activity would entail the high-fidelity modelling and simulation of the gas/surface interaction with the inclusion of the soil
(erosion, cratering, uplifting) under the influence of pulsed jets in a variety of relevant spacecraft conditions. Small-scale experimental
tests are foreseen to validate the modelling and simulation accuracy. The results of the simulations would be used to characterise the
granular flow dynamics over short timescales and the potential feedback effects on the spacecraft during landing. A low-order
empirical model of this extensive characterisation will be derived to facilitate the early design phases of planetary landers.
The characterisation activity will eventually aim to answer the following questions, among others:
1. What is the size distribution, volume and velocities of soil particles lofted by exhaust plumes under different conditions and
configurations?
2. How does the landing zone surface change due to the plume/surface interaction due to recurrent landing operations?
Background and previous activities
The resulting simulations will enable future cross-verification and validation activities using an experimental test facility currently under
development. This facility will allow the testing of plume/regolith interactions under vacuum conditions of Mars and airless bodies (e.g.
© CFD Research/NASA MSFC/Jacobs Space Exploration Group
Moon).
Technical Officer: Jeroen Van den Eynde (jeroen.van.den.eynde@esa.int)
38Hypersonic Shockwave/Boundary-layer
Interaction on Ramps and Flap Deflections
TDE 300 k€ Duration: 12 months Aim: B Ref.: - TRL: 2 to 4
Objective(s)
The objective of the activity is to characterise shockwave/boundary-layer interaction, and in particular the behaviour of the recirculation
region, at hypersonic speeds on a variety of geometries, representative of flap deflections and/or other geometric features of flight
vehicles.
Description
Control surfaces and geometric features on hypersonic flight vehicles induce strong shockwave/boundary-layer interactions (SBLI)
that could directly affect the required design due to thermal and structural loads, and could impact the controllability and flying qualities
of the vehicle. In particular shock-induced separation and reattachment could produce energetically-significant low-frequency
fluctuations and increased structural heating, which could potentially lead to undesirable loads on the structures and decreased flap
efficiency.
While a large number studies have previously addressed the topic of SBLI on compression ramps, limited research has been
performed on the effect of a detached compression ramp, i.e. representing flap deflection with a hinge gap. Such a hinge gap could be © ESA/ASI/RUAG/Thales
present on flaps of real high-speed flight vehicles, and the effects should therefore be understood.
The current activity would look into the dynamics of hypersonic shockwave/boundary-layer interaction of ramps/flaps, considering the
effects of the gap size, deflection angle and incoming boundary-layer state (laminar, turbulent, transitional).
Experimental wind tunnel tests and high-fidelity numerical simulations are expected to be performed, which will yield an extensive
characterisation of the shockwave/boundary-layer interaction behaviour.
Background and previous activities
Previous activities have looked into SBLI on flat plates and compression ramps, but the effects of hinge gaps on the recirculation
region and its dynamics has not been extensively studied.
Technical Officer: Jeroen Van den Eynde (jeroen.van.den.eynde@esa.int) Priebe & Martin (2012), JFM Vol. 699, pp. 1–49
39Multi-metal additives in solid rocket motors
FLPP 300 k€ Duration: 12 months Aim: B Ref.: - TRL: 4 to 5
Objective(s)
To investigate the effect of solid propellant multi-metal additives (i.e. Al-Mg) on a rocket motor performance, and the potential impact
of the resulting plume on the atmospheric environment.
Description
It is very well known that metal additives (e.g. aluminium, boron, etc.) in solid rocket motor propellants can improve the combustion,
performance and/or characteristics of the motor and plume. However, the addition of aluminium, often used in HTPB/AP-based solid
propellant, and combustion, results in aluminium oxide (alumina) in the plume. Alumina particles can have a significant effect on
stratospheric ozone depletion by initiating chlorine activation reactions. Saile et al. (2019), FAR Conference
It has previously been observed that some metal additives can reduce the plume chlorine content significantly, and thereby possibly
counteracting the ozone depletion potential of the plume, decreasing the potential adverse effects on the atmosphere and
environment. For example, the addition of magnesium particles to the propellant mixture can enhance the chlorine reduction, but might
have a negative effect on the combustion and/or performance. Combinations of metal additives (e.g. Al-Mg), either as mixed or
coated particles, could therefore be found to potentially benefit both the performance and environmental effects.
The envisaged activity would entail the testing of multi-metal additives on solid propellant performance, and characterisation of the
resulting plume contents. The potential effects of the plume content, and therefore of the multi-metal additives, on the ozone depletion
potential in the atmosphere will be characterised.
Background and previous activities
Activity is captured in the Technology Harmonisation Dossier 2020 on ‘Fluid Mechanics and Aerothermodynamic Tools’ (B01)
Previous ESA-funded work has looked into the alumina content of solid rocket motors for various propellant formulations
[Experimental Modelling of with Alumina Particulate (EMAP) in Solid Rocket Motors – DLR/PoliMI/FOI].
Zhen et al. (2019), RSC Adv. Issue 33
Technical Officer: Jeroen Van den Eynde (jeroen.van.den.eynde@esa.int)
400D and 1D Aerothermodynamics Tools for Accurate
Modelling
GSTP 300 k€ Duration: 12 months Aim: A Ref.: 02 TRL: 4 to 5
Objectives:
To develop 0D/1D models that can be in conceptual design, used as stand-alone elements or linked to other engineering
tools. To link these with an accurate computational fluid dynamics modelling software.
Description
From conceptual design to operation we need to employ lower-order aerothermodynamics models for different
applications; in conceptual design most of the system model is composed of low-order or re-used elements from earlier
studies. During detail design and operations, the focus shifts to predicting dynamic behaviour of the element/system at
different operational and off-nominal conditions. This activity has two goals; to expand the current array of 0D/1D
modelling tools to cover more of the engineering-level analysis needs (mainly for early design phases) and secondly, to
link these tools to high-fidelity analysis tools, where they provide the boundary conditions.
Modelling areas identified:
• Engineering-level methods for predicting forces and moments on launch vehicles, re-entry vehicles and suborbital
Image source: Detroit Engineered Products
hypersonic aircraft using empirical and semi-empirical models (for example, Drag Breakdown Methods)
• TPS shock, ablation and heat flux models
• Acoustics models to predict environment under launcher fairings
• Ground-plume interaction to model parasitic forces and moments on landers and ascent vehicles, ground pressure
(drives soil erosion and ejected dust-related phenomena).
• Models for forces, moments and heat fluxes for retro-propulsive maneouvres of launch vehicle stages
Background and previous activities
Activity is captured in the Technology Harmonisation Dossier 2020 on ‘Fluid Mechanics and Aerothermodynamic Tools’
(A02). The elements developed in this activity should target compatibility with existing industrial system modelling and
optimisation environments and tools (e.g. ESPSS, ASTOS, Simulink, Modelica). A candidate implementation would be
through the Functional Mock-up Interface (FMI) standard, which describes a standardised container and interface to
exchange dynamic models and is already supported by many of these software. Image source: Empresarios Agrupados/DLR
Technical Officer: Csaba Jéger (csaba.jeger@esa.int)
41Fully Automatic Volume Mesh Generation for Fluid
Dynamics
TDE 300 k€ Duration: 18 months Aim: B Ref.: - TRL: 1 to 3
Objective: To demonstrate the generation of high quality unstructured volume meshes for arbitrary geometries and
boundary conditions using machine learning methods.
Description
Automatic mesh generation has been long sought-after in Computational Fluid Dynamics (CFD). The generation of body-
fitted volume meshes required by most schemes is still a labour-intensive, manual process. Besides post-processing,
mesh generation is close second in man-hour requirements. CFD solutions are heavily influenced by the structure and
topology of the numerical mesh and constructing an suitable one for a given problem requires certain a priori knowledge
about the structure of the flow, which is not feasible to automate using classical algorithms for complex real-world
geometries. Machine learning (ML) techniques could overcome this limitation and replace human interaction entirely for
numerical mesh generation. It has already been demonstrated that these methods are able to roughly predict flowfields
for sub-sonic cases purely based on the geometry and boundary conditions for negligible computational effort.
This activity aims to investigate the application of machine learning methods for general flow computations, focusing on
flowfields with mixed subsonic and supersonic regions in the continuum flow regime. Machine learning techniques are
applied to predict flow features requiring refinement which is then used as an input to size the volume mesh.
Background and previous activities
Flow features in mixed subsonic-supersonic problems are diverse and include rarefaction-recompression waves,
recirculation, flow detachment, shockwave impingement and many others. A successful method will need to learn to
extract these general features and develop an internal approximation of them to be successful on arbitrary geometries
and flow conditions.
An important part of mesh generation is the sizing of the prismatic boundary layer mesh where a sufficiently small first-cell
height is required for accurate boundary layer resolution, but the exact size is the function of local flow conditions. Correct
sizing of this region will be one of the key performance metrics during evaluation. Performance evaluation is quite
straightforward as the CFD solution is considered as ground-truth so we do not deal with the problems of going from the
synthetic training set to real-world data.
Technical Officer: Csaba Jéger (csaba.jeger@esa.int) Image source: https://doi.org/10.1145/3197517.3201325
42Multi-disciplinary Tool Coupling for Flight Vehicle
Engineering
GSTP 400 k€ Duration: 18 months Aim: A Ref.: 04 TRL: 3 to 4
Objectives:
To perform multi-disciplinary breadboard modelling of a flight vehicle, including all major subsystems (propulsion,
thermal, structural, avionics, power, life support, communications, trajectory, aerodynamics) using a coupling of existing
tools and models.
Description
This activity aims to improve interoperability of currently separate models for all major vehicle subsystems. There has been
tighter coupling and existing solutions to couple flow simulations with structural and thermal simulations (Fluid-Structure
Interaction, conjugate heat transfer problems) with mature software tools, but further interaction with other subsystems is
mostly done through ICDs. In upcoming mission and vehicle concepts, it is desirable to achieve earlier and deeper interaction
between these models.
The activity would build out the interfaces and software to couple different domain-specific solvers and models to produce a
full, detail model of a flight vehicle with the aim to demonstrate end-to-end mission simulation. The target benchmark case is
envisaged to be a conceptual launch or re-entry vehicle, or a powered lander (manned or unmanned). The overall design can
be derived from existing examples. Of particular interest is the full simulation of the propulsion system, including power and
hydraulic subsystems, sensors and mechanical actuators and their influence on vehicle external environment, structural loads
and thermal environment. The overall fidelity and granularity of the end-to-end demonstration will depend on the performance
of individual elements, with probably the flow solver being the critical element.
The activity should leverage existing interconnections between solvers and develop an interface where new components can
be brought in with minimal overhead. A candidate implementation would be again through the Functional Mock-up Interface
(FMI) standard. This would also enable synergies with the 0D and 1D Aerothermodynamics Tools activity.
Background and previous activities
Activity is captured in the Technology Harmonisation Dossier 2020 on ‘Fluid Mechanics and Aerothermodynamic Tools’
(A03).
Technical Officer: Csaba Jéger (csaba.jeger@esa.int)
43Validation of methods for rarefied-flow aero-
thermodynamics
TDE 500 k€ Duration: 12 months Aim: D Ref.: - TRL: 3 to 4
Objectives:
To measure, under representative conditions in a wind tunnel, the aerodynamic forces, moments and heat flux
experienced during low-altitude operations (aerobraking, drag-free satellites) phase of several satellite models and
planetary atmospheres. To use the test results to validate the current model of the design and engineering tools.
Description
The aerobraking phase is a major element which enabled various ESA missions, namely Venus Express and ExoMars
2016 and played a major role in the GOCE mission. This technique is employed in e.g. the prospective EnVision mission
with the aim to lower the overall mass of the spacecraft.
The aero-thermodynamic performance of spacecraft manoeuvres in rarefied hypersonic flow in the vicinity of planetary
atmospheres has been studied. Nonetheless, the behaviour of the complex spacecraft geometries considered in real-
wold missions have not yet been well studied experimentally, the results relying on simulation tools with low fidelity
models.
Image source: MARHy/ICARE
The activity shall bridge the identified uncertainty in analysis capability for the future missions by conducting an
experimental campaign in a rarefied flow facility. The data to be obtained shall be the aerodynamic forces, moments and
heat flux on a representative spacecraft and at relevant flight conditions to cover future mission needs, including VLEO
Earth observation satellites, aerobraking missions at Mars, Venus and the gas giants. The results from the test campaign
shall be used to validate high-fidelity numerical tools, which so far have only been validated for simple shapes.
Background and previous activities
Due to the limited number of test facilities available, the representative satellite geometry and flow conditions have to be
tailored to existing capabilties. Depending on available instrumentation, additional flow features could be of high interest,
especially flow composition changes close to the vehicle surface with respect to freestream conditions. A need has been
identified to be able to perform precision composition measurements at low altitudes.
Image source: DOI 10.13009/EUCASS2019-775
Technical Officer: Csaba Jéger (csaba.jeger@esa.int)
44You can also read
