ANALYSIS OF 30 -90 BLENDED WINGLET ADDITIONS TO CESSNA 172, PIPER MALIBU, AND BOEING 737 WINGS - NSF DOD REU MILESTONE. AWARD # 1950207 UNDER ...
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Analysis of 30°-90° Blended Winglet Additions to Cessna 172, Piper Malibu, and Boeing 737 Wings NSF DoD REU Milestone. Award # 1950207 Under Supervision of Dr. Soloiu and Dr. Rahman John Crowe Fernando Ramos
1. Objectives Contents 2. Background Information 3. Experimental Methods 4. Simulations 5. Results 6. Conclusions 7. Acknowledgments
Objectives ● Gather information that will be helpful for winglet design and optimization. ● Verify that a blended winglet addition can increase aerodynamic efficiency. ● Use Computational Fluid Dynamic (CFD) software to find the respective coefficients of lift and drag for each wing-winglet configuration. ● Calculate the coefficients of lift and drag experimentally for comparison. ● Find the cant angle that creates maximum aerodynamic efficiency for each wing. ● Discover the structural consequences of winglet additions.
1. There are only 4 forces acting Aerodynamic on a plane at all times. Forces 2. The aerodynamic efficiency of an aircraft can be determined by the lift to drag ratio. 3. 80% of total drag is caused by friction and induced drag [2]. ○ Frictional drag: Due to skin friction on the boundary layer. Figure 1: Main Forces acting on aircraft [1]. ○ Induced Drag: Caused by wingtip vortices.
1. The Bernoulli’s Principle says How is lift that: generated? “A decrease in pressure results in an increase of velocity” 1. Particles of air are split at the leading edge of the airfoil. The particles following the path at the top move faster than the ones at the bottom. ● The faster air stream creates low pressure at the top of the wing and the slower air stream creates a high pressure Figure 2: Airflow speed around airfoil [2]. below it. This difference creates lift.
1. Formed at the tip of a wing due How are vortices to pressure differences formed? converging. 2. Cause increased induced drag due to vortex hitting wing. 3. Only exist in 3D, real world cases ○ Do not exist for 2D, making Figure 3: Wingtip vortex [3]. them near impossible to analyze by hand.
How do vortices create induced drag? 1. Vortex causes a downwash flow that tilts the lift vector backwards creating induced drag. 2. This lowers the fuel efficiency of the aircraft. Figure 5: Induced drag due to vortex [5].
How do winglets reduce induced drag? 1. The winglet creates lift that is perpendicular to the local relative wind. 2. The generated lift force has a component that opposes the induced drag. Additionally, it reduces the vortex strength Figure 6: Reduction of induced drag due to winglet [5]. and it moves it away from the wing.
Wind Tunnel Experimental Method ● Each wing and winglet combination was attached to a strain transducer setup and pressure tubes were attached to the surface of each wing. ● Setup was placed in the wind tunnel. The speed of the airflow was 10 m/s. ● Lift and drag force from transducer were recorded. ● Pressure difference from top and bottom of the wing was recorded to gather lift force.
Selected wing geometries Technical and wing specifications were based on real modes [7-10].
Winglet Geometries 1. This research aimed to determine the aerodynamic/structural effect of the change of cant angle of the blended winglets. 2. Winglets with cant angles of: ○ 30° ○ 60° Figure 7: Cant angle of a winglet [11]. ○ 90°
1. SolidWorks was used to design Test Models the wing and winglet models. 2. This models were transferred to ANSYS for airflow simulation. ● SolidWorks was used to design 3. Models were also 3D printed and the wing and winglet assembled together using crazy models.This models were glue. transferred to ANSYS for Figure 8: SolidWorks model of Cessna 172 wing. 4. Primer was sprayed over the wing airflow simulation. and then they were smoothed out ● Models were also 3D printed using sandpaper. and assembled together using crazy glue. ● Primer was sprayed over the wing and then they were smoothed out using sandpaper Figure 9: SolidWorks blended winglets models.
3D printed Wing Models Figure 10: Cessna 172 3D printed model. Figure 11: Piper PA-46 3D printed model. Figure 12: Boeing 737-300 3D printed model.
3D Printed Winglet Models Figure 13: 3D printed blended winglets.
Wind tunnel Experimentation - Wind tunnel ● Frequency controlled wind speed. ● Air speed range is 1 to 13 m/s. ● Inlet has a mesh to homogenize the flow. ● 4 ft2 wind outlet. Figure 14: Strain Transducer Setup.
Reynold’s Number ● Re = Reynold’s number. Equation for Reynold’s number: ● Dimensionless number to determine flight conditions. ● Reynold’s number for each wing test: Where: Table 1: Reynolds Number of each Wing . ● ρ = Density of fluid. ● u = Speed of fluid. Wing Type Re ● L = Characteristic length. ● μ = Viscosity of fluid. Cessna 172 7.29e6 Piper Malibu PA-46 5.16e7 Boeing 737-300 5.53e7
Wind tunnel 1. Two S-type load cells were Experimentation - used to determine the overall lift and drag acting on the wing. Strain Transducer 2. Vertical sensor determines overall lift and horizontal sensor determines overall drag. 3. Arduino was used to get a calibrated force reading from both S-type load cells. 4. An LCD was used to display the readings at all times without the need of a computer. Figure 15: Strain Transducer Setup.
Strain Transducer - Arduino 1. Arduino Mega 2560 was used for data processing. 2. The load cell output voltage signal is too small for the Arduino to read (~10 mV). 3. Voltage signal from load cells was amplified using HX711 breakout board. It has a 24-bit Analog to Figure 16: Strain Transducer Arduino sketch [13]. Digital converter (ADC) [12]. 4. It allowed for an accuracy of 5V/224 = 0.298µV (on a 5V source).
Strain Transducer - Calibration 1. A code written by Nathan Seidle [14] was used to determine the coefficient factor that relates the voltage signal to the mass placed over sensor. 2. Once the calibration factor was determined, it was input to a program that determines the force respective to the mass reading with the following equation: Figure 17: Graph that shows accuracy of program used.
Wind tunnel Experimentation - Strain Transducer 1. The strain transducer determines the overall Lift (L) and Drag (D) caused by the wing. The values Where: - CL = Coefficient of lift recorded are then input in - CD = Coefficient of drag - L = Lift Equations 1 and 2 to determine - D = Drag - ρ = density of air the coefficient of lift and drag. - V = velocity of air - A = wing’s surface area
Windtunnel Experimentation - ● Multiple Airspeed Sensor Breakout Board MPXV7002DP Pressure Sensors sensors were used to determine the pressure at the surface of the wings. ● Arduino Mega 2560 was used to receive data from the sensors and output the pressure readings on computer. ● Plastic tubes were placed inside wings. One end was cut at the surface of the wing and the other was connected to the pressure Figure 18: Strain Transducer Setup. sensors.
Pressure Sensors - 1. Arduino Mega 2560 was used for Arduino data processing. 2. It has a 10-bit Analog to Digital Converter (ADC). 3. Allowed for an accuracy of 3.3V/210 = 3.22mV. Figure 19: Pressure Sensors Arduino sketch [15].
The slope of the calibration curve Pressure Sensors - allowed to find the factor value that Calibration Curve correlates the voltage signal to its respective pressure. Equation 3 was implemented in the code to determine the average pressure difference. Figure 20: Graph that shows accuracy of program used.
Windtunnel - Pressure Sensors Experimentation ● Average top and bottom pressure allow ● This relationship can be solved for to calculate the average pressure average force: difference that is acting on the wing. ● It is known that: ● Substituting Lift in Equation 1, the coefficient of lift can be determined:
Figure 21: Experimental Setup.
Computational Fluid Dynamic Simulations
Simulation Equations ● The Navier Stokes governing equations for flow calculation (Eq. 1-4.)
Simulation equations (cont.) ● For the simulations, the k-omega Shear Stress Transport (SST) model within ANSYS fluent was used to model the turbulence of the airflow as it has high accuracy for predicting boundary layers and flow separation [5].
1. Large, meshed domain to CFD Simulations capture vortex formation Using ANSYS Fluent around wing & winglet. 2. Angle of attack simulated at 0°, 5°, and 10° for all wing/winglet configurations. 1. Observed outputs: ○ Coefficients of lift and drag. ○ Pressure and velocity contours. ○ Overall vortex formation. Figure 23: Mesh for Cessna 172 with 60° winglet. Figure 22: Flow domain for Cessna 172 with 60° winglet.
1. Surface pressure imported FEA Simulations from CFD Simulations 2. Determined maximum stress, strain, modal stress, and transient stress for each model 3. Al 7075-T6 used for material of model Table 2: Properties of material used in FEA[16]. Material Young’s Poisson's Ratio Density Modulus Aluminum 71.7GPa 0.33 2.81g/cm3 Figure 24: Imported pressure, gravity and fixed Alloy 7075-T6 support for Boeing 737-300 wing
Experimental and Simulation Results
Cessna 172: Wind Tunnel
Cessna 172: SImulation
Cessna 172: Example velocity contours ● No winglet at α = 5 ● 60° winglet at α = 5
Piper Malibu PA-46: Wind Tunnel
Piper Malibu PA-46: Simulation
Piper PA-46: Example velocity contours ● No winglet at α = 5 ● 60° winglet at α = 5
Boeing 737-300: Wind Tunnel
Boeing 737-300: Simulation
Boeing 737-300: Example velocity contours ● No winglet at α = 5 ● 60° winglet at α = 5
Finite Element Analysis Results
Cessna 172 Figure 25: Deformation for Cessna 0° (top) and 90° (bottom) winglet at 5° angle of attack.
Piper Malibu PA-46 Figure 26: Deformation for Piper PA-46 0° (top) and 90° (bottom) winglet at 5° angle of attack.
Boeing 737-300 Figure 27: Deformation for Boeing 737 0° (top) and 60° (bottom) winglet deformation at 5° angle of attack.
Conclusions ● All winglets tested more beneficial over wing without winglet ● The 60° winglet was the best for the Cessna 172, the 30° winglet was the best for the Piper PA-46, and the 90° was the best for the Boeing 737-300. ● As airspeed increases, the positive effect of a winglet reduces ● Lower cant angles more beneficial for lower airspeed, higher cant angles for higher airspeed. ● Winglets do increase stress on wing, but not by large margin. ● Results mostly comparative, further research would allow for exact results for each case for all operating conditions
Acknowledgements ● Thank you to Dr. Rahman and Dr. Soloiu for allowing us to use your instruments and facilities, as well as allowing us the amazing opportunity to be a part of this program. ● We also thank the Department of Defense and National Science Foundation for funding the research involved in this study under Assure REU Site Award 1950207 ● Thank you to Charles Fricks, Evan Cathers, and Eric Pernell in assisting us hands-on throughout the research with preparing simulations, as well as preparing the wind tunnel and models for these experiments. ● Thank you to everyone involved in the REU program for all of your help and advice.
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