An Experimental Study of Heat Transfer and Film Cooling on Low Aspect Ratio Turbine Nozzles

1990 ◽  
Vol 112 (3) ◽  
pp. 488-496 ◽  
Author(s):  
K. Takeishi ◽  
M. Matsuura ◽  
S. Aoki ◽  
T. Sato
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Film Cooling ◽  
Three Dimensional ◽  
Horseshoe Vortex ◽  
Three Dimensional Flow ◽  
Flow Passage ◽  
Pressure Surface ◽  
Low Aspect Ratio ◽  
Complex Phenomena

The effects of the three-dimensional flow field on the heat transfer and the film cooling on the endwall, suction, and pressure surface of an airfoil were studied using a low speed, fully annular, low aspect h/c = 0.5 vane cascade. The predominant effects on the horseshoe vortex, secondary flow, and nozzle wake of increases in the heat transfer and decreases in the film cooling on the suction vane surface and the endwall were clearly demonstrated. In addition, it was demonstrated that secondary flow has little effect on the pressure surface. Pertinent flow visualization of the flow passage was also carried out for better understanding of these complex phenomena. Heat transfer and film cooling on the fully annular vane passage surface are discussed.

scholarly journals An Experimental Study of Heat Transfer and Film Cooling on Low Aspect Ratio Turbine Nozzles

1989 ◽  
Author(s):  
K. Takeishi ◽  
M. Matsuura ◽  
S. Aoki ◽  
T. Sato
Keyword(s):  
Heat Transfer ◽  
Secondary Flow ◽  
Film Cooling ◽  
Three Dimensional ◽  
Horseshoe Vortex ◽  
Three Dimensional Flow ◽  
Flow Passage ◽  
Pressure Surface ◽  
Low Aspect Ratio ◽  
Complex Phenomena

The effects of the three-dimensional flow field on the heat transfer and the film cooling on the endwall, suction and pressure surface of an airfoil were studied using a low speed, fully annular, low aspect h/c=0.5 vane cascade. The predominant effects that the horseshoe vortex, secondary flow, and nozzle wake increases in the heat transfer and decreases in the film cooling on the suction vane surface and the endwall were clearly demonstrated. In addition, it was demonstrated that secondary flow has little effect on the pressure surface. Pertinent flow visualization of the flow passage was also carried out for better understanding of these complex phenomena. Heat transfer and film cooling on the fully annular vane passage surface is discussed.

scholarly journals Comparison of Predicted and Experimental Nusselt Number for a Film-Cooled Rotating Blade

1996 ◽  
Author(s):  
Vijay K. Garg ◽  
Reza S. Abhari
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Turbine Blade ◽  
Film Cooling ◽  
Three Dimensional ◽  
Tip Clearance ◽  
Computational Domain ◽  
Pressure Surface ◽  
Rotating Blade ◽  
Film Cooling Holes

The predictions from a three-dimensional Navier-Stokes code have been compared to the Nusselt number data obtained on a film-cooled, rotating turbine blade. The blade chosen is the ACE rotor with five rows containing 93 film cooling holes covering the entire span. This is the only film-cooled rotating blade over which experimental heat transfer data is available for the present comparison. Over 2.25 million grid points are used to compute the flow over the blade. Usually in a film cooling computation on a stationary blade, the computational domain is just one spanwise pitch of the film-cooling holes, with periodic boundary conditions in the span direction. However, for a rotating blade, the computational domain consists of the entire blade span from hub to tip, as well as the tip clearance region. As far as the authors are aware of, the present work offers the first comparison of the prediction of surface heat transfer using a three dimensional CFD code with film injection and the measured heat flux on a fully film-cooled rotating transonic turbine blade. In a detailed comparison with the measured data on the suction surface, a reasonably good comparison is obtained, particularly near the hub section. On the pressure surface, however, the comparison between the data and the prediction is poor. A potential reason for the discrepancy on the pressure surface could be the presence of unsteady effects due to stator-rotor interaction in the experiments which are not modeled in the present numerical computations.

scholarly journals Effects of Gaps Between Side-Walls and60∘Ribs on the Heat Transfer and Rib Induced Secondary Flow Inside a Stationary and Rotating Cooling Channel

2001 ◽  
Vol 7 (6) ◽  
pp. 425-433
Author(s):  
Robert Kiml ◽  
Sadanari Mochizuki ◽  
Akira Murata
Keyword(s):  
Heat Transfer ◽  
Flow Visualization ◽  
Secondary Flow ◽  
Three Dimensional ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Cooling Channel ◽  
Three Dimensional Flow ◽  
Side Walls ◽  
Visualization Experiments

The present study investigates the effects of gaps between the side-walls and60∘ribs on the local heat transfer distribution between two consecutive ribs. The heat transfer and flow visualization experiments were carried out inside a straight rib-roughened duct with the ribs mounted on two opposite side walls with and without the gaps. The results showed that the existence of the gaps appreciably enhances the Nu in the area between two consecutive ribs. It is caused by (1) the introduction of the fresh air through the gaps into this region, and (2) the improvement of the three-dimensional flow structure in the area between the two ribs.

A Comparison of Secondary Flow in a Vane Cascade and a Curved Duct

1989 ◽  
Vol 111 (4) ◽  
pp. 530-536 ◽  
Author(s):  
M. T. Boyle ◽  
M. Simonds ◽  
K. Poon
Keyword(s):  
Secondary Flow ◽  
Three Dimensional ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Aerodynamic Characteristics ◽  
Duct Flow ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Cascade Flow ◽  
Flow Through

This paper describes an experiment performed to measure the aerodynamic characteristics of the three-dimensional flow through a linear cascade of turbine vanes. The three-dimensional cascade flow is compared to the three-dimensional flow through a duct with a shape similar to the cascade passage shape. The measurements provide a description of the cascade flow and of the duct flow. By comparing the viscous flows for these two geometries, the usefulness of the duct shape for simulating cascade aerodynamics is evaluated. Except in the leading edge region, the qualities of the two flows are very similar. However the secondary flow is stronger in the duct passage than in the vane cascade passage. The effect on the cascade passage flow of the horseshoe vortex generated around the leading edge of each vane is shown to be limited to the region near the leading edge/endwall junction.

Heat Transfer Coefficient Measurements on the Film-Cooled Pressure Surface of a Transonic Airfoil

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Paul M. Kodzwa ◽  
John K. Eaton
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Steady State ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Wide Band ◽  
Heat Fluxes ◽  
Pressure Surface ◽  
Lift Off ◽  
Transonic Airfoil

This paper presents isoenergetic temperature and steady-state film-cooled heat transfer coefficient measurements on the pressure surface of a modern, highly cambered transonic airfoil. A single passage model simulated the idealized two-dimensional flow path between blades in a modern transonic turbine. This set up offered a simpler construction than a linear cascade but produced an equivalent flow condition. Furthermore, this model allowed the use of steady-state, constant surface heat fluxes. We used wide-band thermochromic liquid crystals (TLCs) viewed through a novel miniature periscope system to perform high-accuracy (±0.2 °C) thermography. The peak Mach number along the pressure surface was 1.5, and maximum turbulence intensity was 30%. We used air and carbon dioxide as injectant to simulate the density ratios characteristic of the film cooling problem. We found significant differences between isoenergetic and recovery temperature distributions with a strongly accelerated mainstream and detached coolant jets. Our heat transfer data showed some general similarities with lower-speed data immediately downstream of injection; however, we also observed significant heat transfer attenuation far downstream at high blowing conditions. Our measurements suggested that the momentum ratio was the most appropriate variable to parameterize the effect of injectant density once jet lift-off occurred. We noted several nonintuitive results in our turbulence effect studies. First, we found that increased mainstream turbulence can be overwhelmed by the local augmentation of coolant injection. Second, we observed complex interactions between turbulence level, coolant density, and blowing rate with an accelerating mainstream.

scholarly journals Comparison of Two-Equation Turbulence Models for Prediction of Heat Transfer on Film-Cooled Turbine Blades

1997 ◽  
Author(s):  
Vijay K. Garg ◽  
Ali A. Ameri
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Computer Time ◽  
Suction Surface ◽  
The Heat Transfer Coefficient

A three-dimensional Navier-Stokes code has been used to compute the heat transfer coefficient on two film-cooled turbine blades, namely the VKI rotor with six rows of cooling holes including three rows on the shower head, and the C3X vane with nine rows of holes including five rows on the shower head. Predictions of heat transfer coefficient at the blade surface using three two-equation turbulence models, specifically, Coakley’s q-ω model, Chien’s k-ε model and Wilcox’s k-ω model with Menter’s modifications, have been compared with the experimental data of Camci and Arts (1990) for the VKI rotor, and of Hylton et al. (1988) for the C3X vane along with predictions using the Baldwin-Lomax (B-L) model taken from Garg and Gaugler (1995). It is found that for the cases considered here the two-equation models predict the blade heat transfer somewhat better than the B-L model except immediately downstream of the film-cooling holes on the suction surface of the VKI rotor, and over most of the suction surface of the C3X vane. However, all two-equation models require 40% more computer core than the B-L model for solution, and while the q-ω and k-ε models need 40% more computer time than the B-L model, the k-ω model requires at least 65% more time due to slower rate of convergence. It is found that the heat transfer coefficient exhibits a strong spanwise as well as streamwise variation for both blades and all turbulence models.

Effect of Wake Passing on Unsteady Aerodynamic Performance in a Turbine Stage

2006 ◽  
Author(s):  
K. Yamada ◽  
K. Funazaki ◽  
K. Hiroma ◽  
M. Tsutsumi ◽  
Y. Hirano ◽  
...  
Keyword(s):  
Secondary Flow ◽  
Three Dimensional ◽  
Suction Side ◽  
Turbine Stage ◽  
Three Dimensional Flow ◽  
Unsteady Aerodynamic ◽  
Unsteady Effect ◽  
Unsteady Rans ◽  
Wake Passing ◽  
Stage Efficiency

In the present work, unsteady RANS simulations were performed to clarify several interesting features of the unsteady three-dimensional flow field in a turbine stage. The unsteady effect was investigated for two cases of axial spacing between stator and rotor, i.e. large and small axial spacing. Simulation results showed that the stator wake was convected from pressure side to suction side in the rotor. As a result, another secondary flow, which counter-rotated against the passage vortices, was periodically generated by the stator wake passing through the rotor passage. It was found that turbine stage efficiency with the small axial spacing was higher than that with the large axial spacing. This was because the stator wake in the small axial spacing case entered the rotor before mixing and induced the stronger counter-rotating vortices to suppress the passage vortices more effectively, while the wake in the large axial spacing case eventually promoted the growth of the secondary flow near the hub due to the migration of the wake towards the hub.

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