1. Boundary Layer Control with Injection and Suction Through a Porous Wall By Crisen McKenzie

2. Why Control Boundary Layer Preventing flow separation Controlling flow turbulence Heat transfer Increasing/Decreasing drag

3. Suction of the Boundary Layer Decreases thickness of boundary layer Increases heat transfer from body to fluid Delays flow separation Allows for less turbulent flow Decreases maximum velocity downstream of flow

4. Blowing Into Boundary Layer Increases thickness of boundary layer Decreases heat transfer Allows for more turbulent flow Flow separation occurs sooner Greater maximum velocity of downstream to the flow

5. ANALYSIS

6. Fluent 2D Pipe flow with Suction/Injection Pipes located normal to fluid flow Three conditions –Normal –Suction –Injection

7. Flow Control Apparatus 1 1.Inlet 2.Outlet 3.Suction Pipes 2 3 0.4 m

8. Regular Pipe flow Regular Poiseuille flow Inlet Pressure: 10 kPa Outlet Pressure: ambient

9. Regular Mainstream Flow w/ No Outer Disturbances Boundary Layer Thickness

10. Suction Boundary Conditions Regular poiseuille flow Inlet pressure: 10 kPa Outlet pressure: ambient Suction pipe pressure: -1kPa

11. Normal vs. Suction Boundary Layer Thickness Velocity(m/s) Boundary Layer Thickness Increased velocity close to wall Velocity(m/s)

12. Injection Boundary Conditions Regular poiseuille flow Inlet pressure: 10 kPa Outlet pressure: ambient Injection pipe pressure: 1 kPa

13. Normal vs. Injection Boundary Layer Thickness Velocity(m/s) Boundary Layer Thickness Decreased velocity close to wall Velocity(m/s)

14. Velocity Graphs InjectionSuction

15. Cross-sectional View of Velocity Profile 1 m Down Pipe

16. Tube Wall

17. Turbulence Boundary Layer SuctionInjection

18. Cross-Sectional View of Turbulence 1 m Down Pipe

19. Tube Wall

20. Heat Transfer Lower skin friction C f means lower heat transfer

21. Heat Transfer Graph InjectionSuction Tw = 100 K T∞ = 300 K

22. Applications Preventing flow separation on wing. Decreasing parasitic drag on wing. Keeping turbine blades cool Decreasing boundary layer interference in wind tunnels. etc

23. Conclusion Controlling boundary layer can be very powerful when used. Used quite heavily in the aerospace environment. Both Suction and Blowing have their Pros and Cons and Used for different applications