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EFFECTS OF FREESTREAM TURBULENCE ON TURBINE BLADE HEAT TRANSFER Robert J. Boyle NASA Glenn Research Center Cleveland, OH Paul W. Giel QSS Group Cleveland, OH Forrest E. Ames University of North Dakota Grand Forks, ND
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NASA/TM—2004-212913
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NASA/TM—2004-212913
Effects of Freestream Turbulence on Turbine Blade Heat Transfer
135
Robert J. Boyle NASA Glenn Research Center Paul W. Giel QSS Group at Glenn Research Center Forrest E. Ames University of North Dakota
NASA/TM—2004-212913
Objectives
136
• Account for Turbulence level and length scale on turbine blade heat transfer • Compare measured and predicted vane & rotor blade heat transfer • Compare predictions with and without models to account for freestream turbulence effects • Identify areas where modeling improvements are needed
NASA/TM—2004-212913
Models Examined
137
1) No Augmentation 2) Smith & Kuethe – No length scale effect 3) Smith & Kuethe + Van Fossen – Length scale modeled using Leading edge data 4) Ames model with Leading edge term 5) Ames model without Leading edge term
NASA/TM—2004-212913 138
Vanes Name
Re2 X10-6
Tu,%
L/C
Description
Ames
0.5 - 0.8
1-20
0.08-0.3
M2=0.17 - 0.27
Ames
0.5 - 2.0
1-20
0.07-0.23
Incompressible
Thole
0.5 & 1.1
1-20
0.08
Incompressible
Arts
0.5 - 2.0
1-6
> 0.05
Transonic
Name
Re2 X10-6
Tu, %
L/C
Description
Giel-1
0.5 - 0.87
13
0.17
M2=0.56 - 0.8
Giel-2
0.4 - 3.8
13
0.17
M2=0.33 - 0.9
Arts
0.6 – 2.3
1-6
> 0.04
Transonic
Rotors
NASA/TM—2004-212913
Calculation procedure
139
• 2D Navier-Stokes (RVCQ3D) – Primarily concerned with leading edge and pressure side • Two layer algebraic turbulence model • Freestream turbulence effects serve to augment laminar viscosity • No augmentation when flow is turbulent • Length scale constant – No variation in length with flow acceleration or deceleration
NASA/TM—2004-212913
Turbulence Augmentation Models
Smith and Kuethe model
νTu / νLam = C SK TuUy 140
CSK = 0.164 Smith & Kuethe + Van Fossen’s Leading edge model 1/3
ν Tu / ν Lam = 0 .3C SK TuUy ( D LE / L )
NASA/TM—2004-212913
Ames – No Leading Edge effect
ν Tu
⎡ ⎛ − 2 .9 y ⎞ ⎤ = 0.135 Tu U L ⎢1 − exp ⎜ ⎟⎥ ⎝ L ⎠⎦ ⎣
•Incorporating a model for turbulence effects improves agreement with data •Ames’s model without leading edge effect showed the most promise •Smith & Kuethe recalibrated using Van Fossen’s data showed similar results
NASA/TM—2004-212913
Issues Identified
151
• Length scale variation with freestream velocity not examined •Variation of start or length of transition with length scale not identified – May be important in favorable pressure gradients.
