An Experimental Convective Heat Transfer Investigation Around a Film-Cooled Gas Turbine Blade

1990 ◽  
Vol 112 (3) ◽  
pp. 497-503 ◽  
Author(s):  
C. Camci ◽  
T. Arts
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Gas Turbine ◽  
Convective Heat ◽  
Free Stream ◽  
Weight Ratio ◽  
Leading Edge ◽  
Suction Side ◽  
Turbine Rotor ◽  
Free Stream Turbulence

The present paper deals with an experimental convective heat transfer investigation around a film-cooled, high-pressure gas turbine rotor blade mounted in a stationary, linear cascade arrangement. The measurements were performed in the von Karman Institute Isentropic Light Piston Compression Tube facility. The test blade was made of Macor glass ceramic and was instrumented with thin film gages. The coolant flow was ejected simultaneously through the leading edge (three rows of holes), the suction side (two rows of holes), and the pressure side (one row of holes). The effects of overall mass weight ratio, coolant to free-stream temperature ratio, and free-stream turbulence were successively investigated.

High Free-Steam Turbulence Effects on Endwall Heat Transfer for a Gas Turbine Stator Vane

2000 ◽  
Vol 122 (4) ◽  
pp. 699-708 ◽  
Author(s):  
R. W. Radomsky ◽  
K. A. Thole
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Gas Turbine ◽  
Convective Heat ◽  
Free Stream ◽  
Leading Edge ◽  
Horseshoe Vortex ◽  
Free Stream Turbulence ◽  
Stator Vane ◽  
The Mean

High free-stream turbulence along a gas turbine airfoil and strong secondary flows along the endwall have both been reported to increase convective heat transfer significantly. This study superimposes high free-stream turbulence on the naturally occurring secondary flow vortices to determine the effects on the flowfield and the endwall convective heat transfer. Measured flowfield and heat transfer data were compared between low free-stream turbulence levels (0.6 percent) and combustor simulated turbulence levels (19.5 percent) that were generated using an active grid. These experiments were conducted using a scaled-up, first-stage stator vane geometry. Infrared thermography was used to measure surface temperatures on a constant heat flux plate placed on the endwall surface. Laser-Doppler Velocimetry (LDV) measurements were performed of all three components of the mean and fluctuating velocities of the leading edge horseshoe vortex. The results indicate that the mean flowfields for the leading edge horseshoe vortex were similar between the low and high free-stream turbulence cases. High turbulence levels in the leading edge–endwall juncture were attributed to a vortex unsteadiness for both the low and high free-stream turbulence cases. While, in general, the high free-stream turbulence increased the endwall heat transfer, low augmentations were found to coincide with the regions having the most intense vortex motions. [S0889-504X(00)00704-2]

Study of the Convective Heat Transfer in a Rotating Coolant Channel

1989 ◽  
Vol 111 (1) ◽  
pp. 43-50 ◽  
Author(s):  
J. Guidez
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Test Section ◽  
Suction Side ◽  
Turbine Rotor ◽  
Internal Cavity ◽  
Transfer Coefficients ◽  
Orthogonal Axis ◽  
Friction Forces

An experimental and theoretical study of convective heat transfer in a rotating coolant channel was inspired by the potential application to cooled turbine rotor blades. The flow that circulates into the internal cavity of the blade is subjected to Coriolis and centrifugal forces, in addition to pressure and friction forces. In this study, the channel is a rectangular-sectioned duct that rotates around an orthogonal axis. The experimental rig is composed of a vacuum enclosure, which includes an electric furnace, and the test section, heated by radiative flux. The temperatures of the wall test section are measured with thermocouples and the infrared pyrometer technique still under development. The convective heat transfer coefficients are determined with transient or steady-state techniques. It is shown that Coriolis acceleration has a beneficial influence on mean heat transfer. Locally, along the pressure side, the transfer increases strongly and on the contrary along the suction side, it decreases slightly. These effects are analyzed theoretically with a Navier-Stokes three dimensional (with mixing length model of turbulence) and explained by the influence of Coriolis force, which induces a secondary flow and distorts the velocity and temperature profiles. Experimental and theoretical results are presented and discussed.

Effect of Incidence on Wall Heating Rates and Aerodynamics on a Film-Cooled Transonic Turbine Blade

1991 ◽  
Vol 113 (3) ◽  
pp. 493-501 ◽  
Author(s):  
C. Camci ◽  
T. Arts
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Convective Heat Transfer ◽  
Stagnation Point ◽  
Short Duration ◽  
Convective Heat ◽  
Film Cooling ◽  
Free Stream ◽  
Suction Side ◽  
Pressure Side

This study investigates the influence of incidence on convective heat transfer to highly curved surfaces of a film-cooled turbine rotor blade. A computational study of free-stream inviscid aerodynamics without cooling at various incidences is followed by well-documented measured heat transfer data sets. The heat transfer experiments are discussed for cases with and without film cooling, performed under realistic gas turbine flow conditions in the short-duration heat transfer facility of the von Karman Institute for Fluid Dynamics. The precise location of the stagnation point and the iso-Mach number contours in the passage for each incidence (−10, 0, 10, +15 deg) are presented for a nominal exit Mach number of 0.94. The free-stream mass flow rate was kept constant for each experiment at different incidence levels. Three rows of compound angled discrete cooling holes are located near the leading edge in a showerhead configuration. Two rows of staggered discrete cooling holes are located on the suction side and a single row of cooling holes is located on the pressure side. The short-duration measurements of quantitative wall heat fluxes on nearly isothermal blade surfaces both in the presence and absence of coolant ejection are presented. The study indicated that the change of the position of the stagnation point strongly altered the aerodynamic behavior and convective heat transfer to the blade in approximately the first 30 percent of both the pressure side and the suction side in the presence and absence of film cooling. The immediate vicinity of the stagnation point was not significantly affected by changing incidence without cooling. Transitional behavior both on the suction surface and on the pressure surface was significantly influenced by the changes in approaching flow direction. Flow separation associated with incidence variations was also observed. Extremely low levels of the convective heat transfer coefficients were experienced near the regions where small separation bubbles are located.

Convective Heat Transfer Through Film Cooling Holes of a Gas Turbine Blade Leading Edge

2005 ◽  
Author(s):  
Elon J. Terrell ◽  
Brian D. Mouzon ◽  
David G. Bogard
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Gas Turbine ◽  
Turbine Blade ◽  
Convective Heat ◽  
Film Cooling ◽  
Leading Edge ◽  
Gas Turbine Blade ◽  
Film Cooling Holes ◽  
Blade Leading Edge

Studies of film cooling performance for a turbine airfoil predominately focus on the reduction of heat transfer to the external surface of the airfoil. However, convective cooling of the airfoil due to coolant flow through the film cooling holes is potentially a major contributor to the overall cooling of the airfoil. This study used experimental and computational methods to examine the convective heat transfer to the coolant as it traveled through the film cooling holes of a gas turbine blade leading edge. Experimental measurements were conducted on a model gas turbine blade leading edge composed of alumina ceramic which approximately matched the Biot number of an engine airfoil leading edge. The temperature rise in the coolant from the entrance to the exit of the film cooling holes was measured using a series of internal thermocouples and an external traversing thermocouple probe. A CFD simulation of the model of the leading edge was also done in order to facilitate the processing of the experimental data and provide a comparison for the experimental coolant hole heat transfer. Without impingement cooling, the coolant hole heat transfer was found to account for 50 to 80 percent of the airfoil internal cooling, i.e. the dominating cooling mechanism.

Effect of Incidence on Wall Heating Rates and Aerodynamics on a Film Cooled Transonic Turbine Blade

1990 ◽  
Author(s):  
Cengiz Camci ◽  
Tony Arts
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Convective Heat Transfer ◽  
Stagnation Point ◽  
Short Duration ◽  
Convective Heat ◽  
Film Cooling ◽  
Free Stream ◽  
Suction Side ◽  
Pressure Side

This study investigates the influence of incidence on convective heat transfer to highly curved surfaces of a film cooled turbine rotor blade. A computational study of free stream inviscid aerodynamics without cooling at various incidences is followed by well documented measured heat transfer data sets. The heat transfer experiments are discussed for cases with and without film cooling, performed under realistic gas turbine flow conditions in the short duration heat transfer facility of the von Karman Institute for Fluid Dynamics. The precise location of the stagnation point and the iso-Mach number contours in the passage for each incidence (−10°, 0°, 10°, +10°) are presented for a nominal exit Mach number of 0.94. The free stream mass flow rate was kept constant for each experiment at different incidence levels. Three rows of compound angled discrete cooling holes are located near the leading edge in a shower-head configuration. Two rows of staggered discrete cooling holes are located on the suction side and a single row of cooling holes is located on the pressure side. The short duration measurements of quantitative wall heat fluxes on nearly isothermal blade surfaces both in the presence and absence of coolant ejection are presented. The study indicated that the change of the position of the stagnation point strongly altered the aerodynamic behaviour and convective heat transfer to the blade in approximately the first 30 % of both the pressure side and the suction side in the presence and absence of film cooling. The immediate vicinity of the stagnation point was not significantly affected by changing incidence without cooling. Transitional behaviour both on the suction surface and on the pressure surface was significantly influenced by the changes in approching flow direction. Flow separation associated with incidence variations was also observed. Extremely low levels of convective heat transfer coefficients were experienced near the regions where small separation bubbles are located.

Studies on Transitional Heat Transfer Characteristics Over Turbine Vane Surface Using a High Order LES Approach

2014 ◽  
Author(s):  
Debasish Biswas
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Gas Turbine ◽  
Free Stream ◽  
Suction Side ◽  
Boundary Layer Transition ◽  
Layer Transition ◽  
Free Stream Turbulence ◽  
Turbine Vane ◽  
Turbine Airfoils

The boundary layer developing on a turbo-machinery blade usually starts as a laminar layer but in most situations it inevitably becomes turbulent. The transition from laminar to turbulent in the boundary layer, which often causes a significant change in operational performance of the machinery, is generally influenced by the free-stream turbulence level, the pressure gradient, and surface curvature, etc. Therefore, boundary layer transition is an important phenomenon experienced by the flow through gas turbine engines. A substantial fraction of the boundary layer on both sides of a gas turbine airfoil may be transitional. The extended transition zone exist due to strong favorable pressure gradients, found on both near the leading edge portion of the suction side and the pressure side, which serve to stabilize the boundary layer and consequently delay the transition process, even under high free-stream turbulence intensity (FSTI) in practical gas turbine. It is very important to properly model and predict the high FSTI transition mechanism, since boundary layer transition leads to substantial increase in friction coefficients and heat transfer rate. Boundary layer separation, which is expected to be a significant problem on the suction side of some high pressure turbine airfoils due to shock-boundary layer interaction, also depends strongly on the state of boundary layer with respect to transition. Acceleration rates, Reynolds numbers and FSTI play very important role in controlling the boundary layer transition on the pressure side of gas turbine airfoils. The main objective of the present work is to study the performance of a high order LES turbulence model in predicting the transitional heat transfer characteristics over turbine vane surface under high pressure turbine flow conditions. In this regard the model is assessed to the precise experimental data where measurements were carried out in moderate temperature using three-vane cascades under steady state conditions. Two types of vane configurations were used in the experiment. The aerodynamic configurations of the two vanes were carefully selected to emphasize fundamental differences in the character of suction surface pressure distributions and the consequent effect on surface heat transfer distributions. In both the experiments and the computations, principle independent parameters (Mach number, Reynolds number, turbulence intensity, and wall-to-gas temperature ratio) were varied over ranges consistent with actual engine operation. The computed results explained measured data very satisfactorily and helped to have a very good understanding of basic mechanism involved in the complex flow behavior and transition from laminar to turbulent flow.

High Freestream Turbulence Effects on Endwall Heat Transfer for a Gas Turbine Stator Vane

2000 ◽  
Author(s):  
R. W. Radomsky ◽  
K. A. Thole
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Gas Turbine ◽  
Convective Heat ◽  
Leading Edge ◽  
Secondary Flows ◽  
Laser Doppler Velocimeter ◽  
Freestream Turbulence ◽  
Stator Vane ◽  
The Mean

High freestream turbulence along a gas turbine airfoil and strong secondary flows along the endwall have both been reported to significantly increase convective heat transfer. This study superimposes high freestream turbulence on the naturally occurring secondary flow vortices to determine the effects on the flowfield and the endwall convective heat transfer. Measured flowfield and heat transfer data were compared between low freestream turbulence levels (0.6%) and combustor simulated turbulence levels (19.5%) that were generated using an active grid. These experiments were conducted using a scaled-up, first stage stator vane geometry. Infrared thermography was used to measure surface temperatures on a constant heat flux plate placed on the endwall surface. Laser Doppler velocimeter (LDV) measurements were performed of all three components of the mean and fluctuating velocities of the leading edge horse-shoe vortex. The results indicate that the mean flowfields for the leading edge horseshoe vortex were similar between the low and high freestream turbulence cases. High turbulence levels in the leading edge-endwall juncture were attributed to a vortex unsteadiness for both the low and high freestream tubulence cases. While, in general, the high freestream turbulence increased the endwall heat transfer, low augmentations were found to coincide with the regions having the most intense vortex motions.

scholarly journals An Experimental Investigation of the Convective Heat Transfer on a Small Helicopter Rotor with Anti-Icing and De-Icing Test Setups

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 96
Author(s):  
Abdallah Samad ◽  
Eric Villeneuve ◽  
Caroline Blackburn ◽  
François Morency ◽  
Christophe Volat
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Leading Edge ◽  
Liquid Water Content ◽  
Rotor Blades ◽  
Direct Result ◽  
Average Error ◽  
Good Prediction ◽  
Series Of Experiments

Successful icing/de-icing simulations for rotorcraft require a good prediction of the convective heat transfer on the blade’s surface. Rotorcraft icing is an unwanted phenomenon that is known to cause flight cancelations, loss of rotor performance and severe vibrations that may have disastrous and deadly consequences. Following a series of experiments carried out at the Anti-icing Materials International Laboratory (AMIL), this paper provides heat transfer measurements on heated rotor blades, under both the anti-icing and de-icing modes in terms of the Nusselt Number (Nu). The objective is to develop correlations for the Nu in the presence of (1) an ice layer on the blades (NuIce) and (2) liquid water content (LWC) in the freestream with no ice (NuWet). For the sake of comparison, the NuWet and the NuIce are compared to heat transfer values in dry runs (NuDry). Measurements are reported on the nose of the blade-leading edge, for three rotor speeds (Ω) = 500, 900 and 1000 RPM; a pitch angle (θ) = 6°; and three different radial positions (r/R), r/R = 0.6, 0.75 and 0.95. The de-icing tests are performed twice, once for a glaze ice accretion and another time for rime ice. Results indicate that the NuDry and the NuWet directly increased with V∝, r/R or Ω, mainly due to an increase in the Reynolds number (Re). Measurements indicate that the NuWet to NuDry ratio was always larger than 1 as a direct result of the water spray addition. NuIce behavior was different and was largely affected by the ice thickness (tice) on the blade. However, the ice acted as insulation on the blade surface and the NuIce to NuDry ratio was always less than 1, thus minimizing the effect of convection. Four correlations are then proposed for the NuDry, the NuWet and the NuIce, with an average error between 3.61% and 12.41%. The NuDry correlation satisfies what is expected from heat transfer near the leading edge of an airfoil, where the NuDry correlates well with Re0.52.

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