1/50 1 Effect of Trailing Edge Geometry on the Flow Behavior through Rectilinear Turbine Cascades By: Mahmoud M. El-Gendi Supervisor: Prof. Yoshiaki Nakamura Graduate school of Engineering, Department of Aerospace Engineering

2/66 Outline Introduction  Background  Motivation  Goal Numerical Methods Results and Discussion  Energy Separation Phenomenon  Vortex Shedding Control  Heat Transfer Effect Conclusion

3/66 Background Airplanes Tanks Micro turbines Ships Power Plants Racing Cars

4/66 Background Airplane Jet engine Experimental set up sieverding et al. Computational cascade

5/66 Background Airplane Jet engine Experimental set up sieverding et al. Trailing edge High pressure turbine cascade ( VKI blade ) Computational cascade Why ?

6/66 Motivation Mass average loss coefficient Langstone et al Trailing edge loss accounts for more than one third of total loss in turbine cascade. Sudden jump in loss next to trailing edge

7/66 Goal Increasing the base pressure and decreasing loss

8/66 Cascade Dimensions All dimensions in mm

9/66 Numerical Methods Single Block Structure in-house Naveir- Stokes code Dual-time method for unsteady calculations LUSGS method for algebraic equations MUSLE scheme to improve the accuracy

10/66 Development & validation of the code 1D, Riemann Invariant 2 D, turbulent, flat plate & turbine cascade Baldwin-Lomax Spalart-Allmaras DES DDES 3D, Parallel, DDES code Parallelization MPI 3D calculation

11/66 Energy Separation Phenomenon

12/66 What is an energy separation phenomenon? Instantaneous total temperature contours Background

13/66 Clarify the mechanism of the energy separation phenomenon Goal

14/66 P o1 =140 kPa T o1 =280 K Inlet M 2,is = 0.79 Re 2 =2.8×10 6 Exit Wall Periodic C C=140 mm High pressure turbine cascade ( VKI blade ) Experimental investigation is carried out by sieverding et al., 2003, J. of Turbomachinery, pp Flow & boundary conditions

15/66 Numerical Methods 2-dimensinal series calculations 2 nd order AUSM scheme for inviscid fluxes Detached Eddy Simulation (DES) for Turbulence.

16/66 The grid point in stream-wise, pitch-wise, and span-wise respectively are With total grid point equal Computational grid

17/66 Suction Side Pressure Side Suction Side Isentropic Mach No. distribution

18/66 Time-average pressure distribution Pressure side suction side Ｓ /D=0.0 +ve -ve Blade Trailing Edge Ｓ /D=-0.65

19/66 Experimental Numerical Pressure trace analysis

20/66 Particle movement and vortex motion Contour lines represent entropy

21/66 Particle movement and vortex motion Contour lines represent entropy Y/D X/D

22/66 Close to Rankine vortex Kinematical explanation Y/D

23/66 Superposition of velocity Resultant velocity Convective velocity Tangential velocity

24/66 Transversal flow quantities Y/D

25/66 Tangential flow quantities

26/66 Mach No. effect M=0.4 M=0.79

27/66 1.The non-uniform pressure distribution at the trailing edge was confirmed numerically. 2.The superposition of convective and rotational velocities of the vortex is the main cause of energy separation phenomenon Summary

28/66 Vortex Shedding Control

29/66 Background Passive control methods Active control methods Reactive control methods Synthetic jet Plasma actuator Through the wake Delay the separation

30/66 Increase the base pressure and decrease loss Goal

31/66 Numerical Methods 3-dimensinal parallel calculations 2 nd order Roe scheme for inviscid fluxes Delayed Detached Eddy Simulation (DDES) for Turbulence.

32/66 total grid point Computational grid

33/ mm o S = 0 SS PS Section x-x Section x x Microtubes Modification of TE Geometry 0.1 mm Why ? Hagen-Poiseuille

34/66 BC without Microtubes S/D Out-of-phase

35/66 Streamlines BCMC

36/66 Vorticity contours BCMC

37/66 Actuation & feedback BCMC

38/66 Pressure Side Suction Side Pressure Side Suction Side Isentropic Mach No. distribution

39/66 Time-average pressure distribution Pressure side suction side Ｓ /D=0.0 +ve -ve Blade Trailing Edge Ｓ /D=-0.65

40/66 BC MC Pressure trace analysis

41/66 Wake coordinate X/D Y/D

42/66 Entropy distribution at X/D=2.5

43/66 1.Our modification maintains the blade load as original geometry, increase the base pressure by 0.7%, and decreases the overall loss by 3%. Summary

44/66 Heat Transfer Effect

45/66 Background Hot Case (HC)Cold Case (CC) High flow temperature Isothermal condition Difficult to implement Very close to real case Low flow temperature Adiabatic condition Easy to implement Approximation of real case

46/66 Verify that our modification can improve the base pressure in the real cascade Goal

47/66 Cascade dimensions C=140 S=97.44 C ax = λ=49.83 o x y PS SS r=0.0 r>0.0 r<0.0 SS PS S/D=0.0 S/D=1.75 S/D=-1.75

48/66 Flow Conditions Re 2,is 10 6 M 2,is T w (K) T o1 K)) P o1 (k Pa) PCFD * CC HC * Luo and Lakshminarayana, ASME, J. of Turbomachinery, 106(1984) PP

49/66 Code validation for HC

50/66 Pressure distribution along the blade

51/66 Total pressure distribution across the BL Suction sidePressure side

52/66 Velocity distribution across the BL Suction sidePressure side

53/66 Temperature distribution across the BL Suction sidePressure side

54/66 Density distribution across the BL Suction sidePressure side

55/66 Pressure trace analysis CCHC 7.45 kHz 7.09 kHz

56/66 Wake coordinate X/D Y/D

57/66 Velocity distribution at X/D=2.5

58/66 Temperature distribution at X/D=2.5

59/66 Density distribution at X/D=2.5

60/66 Total pressure loss coefficient at X/D=2.5

61/66 Energy separation phenomenon Instantaneous total temperature contours CCHC

62/66 Summary GeneralWakeB.L. IIStatic pressure SSTotal pressure SSVelocity SDStatic density SDTotal density DDStatic temperature DDTotal temperature SVortex shedding frequency & amplitude

63/66 Conclusion

64/66 Conclusion The state-of-the-art numerical code was developed and validated successfully The numerical results show reasonable agreement with experimental data The energy separation & vortex shedding were clarified and investigated in depth The novel and hybrid flow control method was proposed

65/66 Conclusion The new geometry of the TE success to improve the base pressure and decrease the loss The similarity and differences between hot and cold flow conditions were indicated It is expected that our modification increases the base pressure also in hot flow condition

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67/66 Pure rolling motion