1. Study of Separated Flow Over Low-Pressure Turbine Blades and Automobiles Using Active Flow Control Strategies Michael Cline Junior Mechanical Engineering Brandon Mullen Sophomore Aerospace Engineering Sponsored By The National Science Foundation Grant ID No.: DUE-0756921… … in cooperation with University of Cincinnati College of Engineering and Applied Science, Cincinnati, Ohio. Project Mentor: Dr. Kirti Ghia

2. 2 Turbofan High Pressure Compressor Combustor High-Pressure Turbine Low-Pressure Turbine Booster/Low Pressure Compressor Image courtesy of GE-Aviation

3. Project Introduction What is flow separation? How is flow controlled? What are the benefits of eliminating separation? 3 Flow Separation Reduced Separation JET CONTROL

4. Project Goals Understand flow separation and its control in various applications. Reduce flow separation using flow control in computation simulations, thereby increasing efficiency. Generate original data to expand knowledge of flow separation control strategies. Project Objectives 1.Review for unique applications/aspects to investigate. 2.Develop proper equations and implementation methods. 3.Successfully simulate and prevent low-speed flow separation. 4.Generate data on flow control strategies and assemble in the form of an AIAA meetings paper and possibly publish in a journal. 4

5. Plasma Actuators Thomas, F. O., Kozlov, A., & Corke, T. C. (2008). “Plasma Actuators for Cylinder Flow Control and Noise Reduction.” AIAA Journal, 1921-1931. 5 Study carried out in two phases: 1)Prior study* geometry and variables. 2)New geometry and variables. *Shyy et al, Journal of Applied Physics (2002) Plasma offPlasma on

6. Phase One: Verify Electric Field and Body Force Values Used previous study* to verify equation implementation. Replicated the geometry and conditions developed by Shyy et al (right). X-velocity profile at same point in geometry was nearly identical (within 14% at worst). 6 Phase One mesh (124x92 points) with electrode (A) and electric field effect (B) geometry. A B Present Normalized X-Velocity Profile Results (left) compared with Shyy et al’s (right).

7. 7 Phase Two: NACA0012 Airfoil Simulation A)Developing the Computational Mesh Electrode placed at flow separation point. Broke upper face into five blocks, for simpler higher- quality meshing. Mesh concentrated near airfoil. A B Phase Two Grid (368x102 points) Adapted electrode (A) and electric field effect (B, outlined) geometry.

8. Phase Two: NACA0012 Airfoil Simulation B) Baseline Case Developed simulation of airflow over NACA0012 airfoil. Simulation run at low fluid velocity, high angle of attack conditions. 8 Results of simulation with no plasma control. 10 °

9. 9 Phase Two: NACA0012 Airfoil Simulation C) Nominal Control Case Activated plasma control. –Used nominal values from Shyy et al study. Control eliminated flow separation. Baseline Case Nominal Case

10. 10 Phase Two: NACA0012 Airfoil Simulation D) Reduced-Voltage Case Attempted to find minimum effective electrode voltage. Voltage could be reduced by 40% and still be very effective. (a) Voltage = Nominal = 4000 V (b) Voltage =.8*Nominal = 3200 V (c) Voltage =.6*Nominal = 2400 V

11. 11 Phase Two: NACA0012 Airfoil Simulation E) Reduced-Frequency Case Attempted to find minimum effective A/C frequency. Frequency could be reduced by 75% and still be very effective. (a) Frequency = Nominal = 3000 Hz (b) Frequency =.5*Nominal = 1500 Hz (c) Frequency =.25*Nominal = 750 Hz

12. Automobile Airflow Control *http://www.mrtperformance.com.au/resources/technical-documents/705-lancer-evo-x-aerodynamics 12

13. Moving Surface Boundary Layer Control (MSBC) How it works Revolving cylinder is placed at beginning of flow separation wake Detached flow is accelerated by cylinder’s surface and reattaches to free stream flow Benefits Very little power is needed to rotate the low mass cylinder Significant reduction in drag *Effect of momentum injection on the aerodynamics of several bluff bodies By: V.J. Modi 13

14. Outline of Testing Developing a Section View –Used MATLAB’s native image processing to create two-dimensional section silhouette Baseline –Majority of time spent configuring simulation parameters and grid geometry MSBC cylinder Modeling –Application of MSBC cylinder on surface of section at various linear velocities 14 Front View of MSBC Cylinder Vertices of Section Baseline Grid Configuration

15. Developing a Section View 15 Decomposition of Image Section for Simulations

16. Baseline Simulation 16 All simulations ran with air stream velocity of 24.58 m/s (55 mph) Moving road surface also modeled within simulations Mesh configured to give more detail over roof section and downstream of section Targeted Separation Wake

17. Application of cylinder 17 ` Exposed Quarter Section (Front and Side Views)

18. MSBC Cylinder 18  Baseline Simulation  MSBC Cylinder with no rotation  MSBC cylinder rotating (~610 rpm) Reduction in Targeted Separation Wake

19. Conclusions Reduced flow separation and increased efficiency can be achieved with flow control. MSBCs and Plasma Actuators are flexible in their energy cost. –MSBC effectiveness mainly a function of surface velocity. –Plasma effectiveness mainly a function of voltage. 19

20. Future Work Quantitative analysis of control wake reduction. Grid independence study. Verification and validation to assure results are correct and are original. Investigation with modified control locations. 20

21. Acknowledgements National Science Foundation –Grant ID DUE - DUE-0756921 The University of Cincinnati Dr. Kirti Ghia and Dr. Urmila Ghia Ms. Kristen Strominger Dr. Anant Kukreti The Graduate Students of the CFDRL 21