Computation
of Turbulent Heat Transfer on the Walls of a 180 Degree Turn Channel With a Low
Reynolds Number Reynolds Stress Model
Ameri, A. A.
(Toledo Univ., OH United States); Rigby, D. L. (QSS Group, Inc., Cleveland, OH
United States); Steinthorsson, E. (A and E
Consulting, Inc., Westlake, OH United States)
NASA Center for AeroSpace Information (CASI)
NASA/CR-2002-211515
The Low Reynolds number version of the Stress-omega model and the two equation
k-omega model of Wilcox were used for the calculation of turbulent heat
transfer in a 180 degree turn simulating an internal coolant passage. The
Stress-omega model was chosen for its robustness. The turbulent thermal fluxes
were calculated by modifying and using the Generalized Gradient Diffusion
Hypothesis. The results showed that using this Reynolds Stress model allowed
better prediction of heat transfer compared to the k-omega two equation model. This improvement however required a finer grid and
commensurately more CPU time.
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Heat
Transfer and Flow on the Blade Tip of a Gas Turbine Equipped with a Mean-Camberline Strip
Ameri, A.A.
(AYT Corp., Brook Park, OH United States)
NASA Center for AeroSpace Information (CASI)
NASA/CR-2001-210764
Experimental and computational studies have been performed to investigate the
detailed distribution of convective heat transfer coefficients on the
first-stage blade tip surface for a geometry typical of large power generation
turbines (greater than 100 MW) In a previous work the numerical heat transfer
results for a sharp edge blade tip and a radiused
blade tip were presented. More recently several other tip treatments have been
considered for which the tip heat transfer has been measured and documented.
This paper is concerned with the numerical prediction of the tip surface heat
transfer for radiused blade tip equipped with mean-camberline strip (or 'squealer' as it is often called). The
heat transfer results are compared with the experimental results and discussed.
The effectiveness of the mean-camberline strip in
reducing the tip leakage and the tip heat transfer as compared to a radiused edge tip and sharp edge tip was studied. The
calculations show that the sharp edge tip works best (among the cases
considered) in reducing the tip leakage flow and the tip heat transfer.
No
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A
Numerical Analysis of Heat Transfer and Effectiveness on Film Cooled Turbine
Blade Tip Models
Ameri, A. A.
(AYT Corp., Brook Park, OH United States); Rigby, D. L. (DYNACS Engineering
Co., Inc., Brook Park, OH United States)
NASA Center for AeroSpace Information (CASI)
NASA/CR-1999-209165
A computational study has been performed to predict the distribution of
convective heat transfer coefficient on a simulated blade tip with cooling
holes. The purpose of the examination was to assess the ability of a
three-dimensional Reynolds-averaged Navier-Stokes
solver to predict the rate of tip heat transfer and the distribution of cooling
effectiveness. To this end, the simulation of tip clearance flow with blowing
of Kim and Metzger was used. The agreement of the computed effectiveness with
the data was quite good. The agreement with the heat transfer coefficient was
not as good but improved away from the cooling holes. Numerical flow
visualization showed that the uniformity of wetting of the surface by the film
cooling jet is helped by the reverse flow due to edge separation of the main
flow.
No
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Heat
Transfer and Flow on the First Stage Blade Tip of a Power Generation Gas
Turbine
Ameri, A. A.
(AYT Corp., Brook Park, OH United States); Bunker, R. S. (General Electric Co.,
Schenectady, NY United States)
NASA Center for AeroSpace Information (CASI)
NASA/CR-1999-209151/PT2
A combined experimental and computational study has been performed to
investigate the detailed distribution of convective heat transfer coefficients
on the first stage blade tip surface for a geometry typical of large power
generation turbines (>1OOMW). This paper is concerned with the numerical
prediction of the tip surface heat transfer. Good comparison with the experimental
measured distribution was achieved through accurate modeling of the most
important features of the blade passage and heating arrangement as well as the
details of experimental rig likely to affect the tip heat transfer. A sharp
edge and a radiused edge tip were considered. The
results using the radiused edge tip agreed better
with the experimental data. This improved agreement was attributed to the
absence of edge separation on the tip of the radiused
edge blade.
No
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Effects
of Tip Clearance and Casing Recess on Heat Transfer and Stage Efficiency in
Axial Turbines
Ameri, A. A.
(AYT Corp., Brook Park, OH United States); Steinthorsson,
E. (NASA Lewis Research Center, Cleveland, OH United States); Rigby, David L.
(NYMA, Inc., Brook Park, OH United States)
NASA Center for AeroSpace Information (CASI)
NASA/CR-1998-208514
Calculations were performed to assess the effect of the tip leakage flow on the
rate of heat transfer to blade, blade tip and casing. The effect on exit angle
and efficiency was also examined. Passage geometries with and without casing
recess were considered. The geometry and the flow conditions of the GE-E 3
first stage turbine, which represents a modem gas turbine blade
were used for the analysis. Clearance heights of 0%, 1%, 1.5% and 3% of the
passage height were considered. For the two largest clearance heights
considered, different recess depths were studied. There was an increase in the
thermal load on all the heat transfer surfaces considered due to enlargement of
the clearance gap. Introduction of recessed casing resulted in a drop in the rate
of heat transfer on the pressure side but the picture on the suction side was
found to be more complex for the smaller tip clearance height considered. For
the larger tip clearance height the effect of casing recess was an orderly
reduction in the suction side heat transfer as the casing recess height was
increased. There was a marked reduction of heat load and peak values on the
blade tip upon introduction of casing recess, however only a small reduction
was observed on the casing itself. It was reconfirmed that there is a linear
relationship between the efficiency and the tip gap height. It was also
observed that the recess casing has a small effect on the efficiency but can
have a moderating effect on the flow underturning at
smaller tip clearances.
No
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Analysis
of Gas Turbine Rotor Blade Tip and Shroud Heat Transfer
Ameri, A. A.
(AYT Corp., Brook Park, OH United States); Steinthorsson,
E. (NASA Lewis Research Center, Cleveland, OH United States)
NASA Center for AeroSpace Information (CASI)
NASA-CR-198541 , 1996
Predictions of the rate of heat transfer to the tip and shroud of a gas turbine
rotor blade are presented. The simulations are performed with a multiblock computer code which solves the Reynolds Averaged
Navier-Stokes equations. The effect of inlet boundary
layer thickness as well as rotation rate on the tip and shroud heat transfer is
examined. The predictions of the blade tip and shroud heat transfer are in
reasonable agreement with the experimental measurements. Areas of large heat
transfer rates are identified and physical reasoning for the phenomena presented.
No
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Prediction
of Unshsrouded Rotor Blade Tip Heat Transfer
Ameri, A. A.
(AYT Corp., Brook Park, OH United States); Steinthorsson,
E. (Ohio Aerospace Inst., Institute for Computational Mechanics in Propulsion
Cleveland, OH United States)
NASA Center for AeroSpace Information (CASI)
NASA-CR-198542 , 1994
The rate of heat transfer on the tip of a turbine rotor blade and on the blade
surface in the vicinity of the tip, was successfully predicted. The
computations were performed with a multiblock
computer code which solves the Reynolds Averaged Navier-Stokes
equations using an efficient multigrid method. The
case considered for the present calculations was the Space Shuttle Main Engine
(SSME) high pressure fuel side turbine. The predictions of the blade tip heat
transfer agreed reasonably well with the experimental measurements using the
present level of grid refinement. On the tip surface, regions
with high rate of heat transfer was found to exist close to the pressure
side and suction side edges. Enhancement of the heat transfer was also observed
on the blade surface near the tip. Further comparison of the predictions was
performed with results obtained from correlations based on fully developed
channel flow.
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Navier-Stokes
turbine heat transfer predictions using two-equation turbulence
Ameri, Ali A.
(NASA Lewis Research Center, Cleveland, OH, United States); Arnone,
Andrea (NASA Lewis Research Center, Cleveland, OH, United States)
NASA Center for AeroSpace Information (CASI)
NASA-TM-105817 , 1992
Navier-Stokes calculations were carried out in order
to predict the heat transfer rates on turbine blades. The calculations were
performed using TRAF2D which is a two-dimensional, explicit, finite volume
mass-averaged Navier-Stokes solver. Turbulence was
modeled using q-omega and k-epsilon two-equation models and the Baldwin-Lomax algebraic model. The model equations along with the
flow equations were solved explicitly on a non-periodic C grid. Implicit
residual smoothing (IRS) or a combination of multigrid
technique and IRS was applied to enhance convergence rates. Calculations were
performed to predict the
No
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