Local heat transfer coefficient measurement through a visibly-transparent heater under jet-impingement cooling

2012 ◽  
Vol 55 (23-24) ◽  
pp. 6410-6424 ◽  
Author(s):  
H.D. Haustein ◽  
G. Tebrügge ◽  
W. Rohlfs ◽  
R. Kneer
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Local Heat Transfer Coefficient ◽  
Impingement Cooling ◽  
Coefficient Measurement

Full Surface Local Heat Transfer Coefficient Measurements in a Model of an Integrally Cast Impingement Cooling Geometry

1998 ◽  
Vol 120 (1) ◽  
pp. 92-99 ◽  
Author(s):  
D. R. H. Gillespie ◽  
Z. Wang ◽  
P. T. Ireland ◽  
S. T. Kohler
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Local Heat Transfer Coefficient ◽  
Target Plate ◽  
Impingement Cooling ◽  
Impingement Plate

Cast impingement cooling geometries offer the gas turbine designer higher structural integrity and improved convective cooling when compared to traditional impingement cooling systems, which rely on plate inserts. In this paper, it is shown that the surface that forms the jets contributes significantly to the total cooling. Local heat transfer coefficient distributions have been measured in a model of an engine wall cooling geometry using the transient heat transfer technique. The method employs temperature-sensitive liquid crystals to measure the surface temperature of large-scale perspex models during transient experiments. Full distributions of local Nusselt number on both surfaces of the impingement plate, and on the impingement target plate, are presented at engine representative Reynolds numbers. The relative effects of the impingement plate thermal boundary condition and the coolant supply temperature on the target plate heat transfer have been determined by maintaining an isothermal boundary condition at the impingement plate during the transient tests. The results are discussed in terms of the interpreted flow field.

Full Surface Local Heat Transfer Coefficient Measurements in a Model of an Integrally Cast Impingement Cooling Geometry

1996 ◽  
Author(s):  
David R. H. Gillespie ◽  
Zuolan Wang ◽  
Peter T. Ireland ◽  
S. Toby Kohler
Keyword(s):  
Heat Transfer ◽  
Boundary Condition ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Local Heat Transfer Coefficient ◽  
Target Plate ◽  
Impingement Cooling ◽  
Impingement Plate

Cast impingement cooling geometries offer the gas turbine designer higher structural integrity and improved convective cooling when compared to traditional impingement cooling systems which rely on plate inserts. In this paper, it is shown that the surface which forms the jets contributes significantly to the total cooling. Local heat transfer coefficient distributions have been measured in a model of an engine wall cooling geometry using the transient heat transfer technique. The method employs temperature sensitive liquid crystals to measure the surface temperature of large scale perspex models during transient experiments. Full distributions of local Nusselt number on both surfaces of the impingement plate, and on the impingement target plate are presented at engine representative Reynolds numbers. The relative effects of the impingement plate thermal boundary condition and the coolant supply temperature on the target plate heat transfer has been determined by maintaining an isothermal boundary condition at the impingement plate during the transient tests. The results are discussed in terms of the interpreted flow field.

The Relative Performance of External Casing Impingement Cooling Arrangements for Thermal Control of Blade Tip Clearance

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Myeonggeun Choi ◽  
David M. Dyrda ◽  
David R. H. Gillespie ◽  
Orpheas Tapanlis ◽  
Leo V. Lewis
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Operating Conditions ◽  
Local Heat Transfer Coefficient ◽  
Tip Clearance ◽  
Local Cooling ◽  
Impingement Cooling

As a key way of improving jet engine performance, a thermal tip clearance control system provides a robust means of manipulating the closure between the casing and the rotating blade tips, reducing undesirable tip leakage flows. This may be achieved using an impingement cooling scheme on the external casing. Such systems can be optimized to increase the contraction capability for a given casing cooling flow. Typically, this is achieved by changing the cooled area and local casing features, such as the external flanges or the external cooling geometry. This paper reports the effectiveness of a range of impingement cooling arrangements in typical engine casing closure system. The effects of jet-to-jet pitch, number of jets, and inline and staggered alignment of jets on an engine representative casing geometry are assessed through comparison of the convective heat transfer coefficient distributions as well as the thermal closure at the point of the casing liner attachment. The investigation is primarily numerical, however, a baseline case has been validated experimentally in tests using a transient liquid crystal technique. Steady numerical simulations using the realizable k–ε, k–ω SST, and EARSM turbulence models were conducted to understand the variation in the predicted local heat transfer coefficient distribution. A constant mass flow rate was used as a constraint at each engine condition, approximately corresponding to a constant feed pressure when the manifold exit area is constant. Sets of local heat transfer coefficient data generated using a consistent modeling approach were then used to create reduced order distributions of the local cooling. These were used in a thermomechanical model to predict the casing closure at engine representative operating conditions.

The Relative Performance of External Casing Impingement Cooling Arrangements for Thermal Control of Blade Tip Clearance

2015 ◽  
Author(s):  
Myeonggeun Choi ◽  
David M. Dyrda ◽  
David R. H. Gillespie ◽  
Orpheas Tapanlis ◽  
Leo V. Lewis
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Operating Conditions ◽  
Local Heat Transfer Coefficient ◽  
Tip Clearance ◽  
Local Cooling ◽  
Impingement Cooling

As a key way of improving jet engine performance, a thermal tip clearance control system provides a robust means of manipulating the closure between the casing and the rotating blade tips, reducing undesirable tip leakage flows. This may be achieved using an impingement cooling scheme on the external casing. Such systems can be optimized to increase the contraction capability for a given casing cooling flow. Typically this is achieved by changing the cooled area, local casing features such as the external flanges, or the external cooling geometry. This paper reports the effectiveness of a range of impingement cooling arrangements in typical engine casing closure system. The effects of jet-to-jet pitch, number of jets, inline and staggered alignment of jets, on an engine representative casing geometry are assessed through comparison of the convective heat transfer coefficient distributions as well as the thermal closure at the point of the casing liner attachment. The investigation is primarily numerical, however, a baseline case has been validated experimentally in tests using a transient liquid crystal technique. Steady numerical simulations using the realizable k-ε, k-ω SST and EARSM turbulence models were conducted to understand the variation in the predicted local heat transfer coefficient distribution. Constant mass flow rate was used as a constraint at each engine condition, this approximately pertaining to a constant feed pressure when the manifold exit area is constant. Sets of local heat transfer coefficient data generated using a consistent modelling approach were then used to create reduced order distributions of the local cooling. These were used in a thermo-mechanical model to predict the casing closure at engine representative operating conditions.

Local Heat Transfer in a Rotating Square Channel With Jet Impingement

1999 ◽  
Vol 121 (4) ◽  
pp. 811-818 ◽  
Author(s):  
S.-S. Hsieh ◽  
J.-T. Huang ◽  
C.-F. Liu
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Average Nusselt Number ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Local Heat Transfer Coefficient

The influence of rotation and jet mass flow rate on the local heat transfer coefficient for a single confined impinging round jet with a fixed jet-to-wall spacing of H/d = 5 was studied for the jet Reynolds number from 6500 to 26,000 and the rotational Reynolds number from 0 to 112,000. The local heat transfer coefficient along the surface is measured and the effect of the rotation on the stagnation (peak) point, local and average Nusselt number, is presented and discussed. Furthermore, a correlation was developed for the average Nusselt number in terms of the parameters of Rej and ReΩ. In general, the combined jet impingement and rotation effect are shown to affect the heat transfer response. Rotation decreases the average Nusselt number values from 15 to 25 percent in outward and inward radial flow, respectively. Finally, comparisons of the present data with existing results for multijets with rotation were also made.

Modeling of Convective Cooling of a Rotating Disk by Partially Confined Liquid Jet Impingement

2008 ◽  
Vol 130 (10) ◽  
Author(s):  
Jorge C. Lallave ◽  
Muhammad M. Rahman
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Jet Impingement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Local Heat Transfer Coefficient ◽  
Liquid Jet

This paper presents the results of the numerical simulation of conjugate heat transfer during a semiconfined liquid jet impingement on a uniformly heated spinning solid disk of finite thickness and radius. This study considered various disk materials, namely, aluminum, copper, silver, Constantan, and silicon; covering a range of Reynolds number (220–900), Ekman number (7.08×10−5–∞), nozzle-to-target spacing (β=0.25–1.0), disk thicknesses to nozzle diameter ratio (b∕dn=0.25–1.67), and Prandtl number (1.29–124.44) using ammonia (NH3), water (H2O), flouroinert (FC-77), and oil (MIL-7808) as working fluids. The solid to fluid thermal conductivity ratio was 36.91–2222. A higher thermal conductivity plate material maintained a more uniform interface temperature distribution. A higher Reynolds number increased the local heat transfer coefficient. The rotational rate also increased the local heat transfer coefficient under most conditions.

Local and Average Heat Transfer Characteristics for a Disk Situated Perpendicular to a Uniform Flow

1985 ◽  
Vol 107 (2) ◽  
pp. 321-326 ◽  
Author(s):  
E. M. Sparrow ◽  
G. T. Geiger
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Stagnation Point ◽  
Radial Distance ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Local Heat Transfer Coefficient ◽  
Average Heat ◽  
Radial Profiles

Wind tunnel experiments were performed to determine both the average heat transfer coefficient and the radial distribution of the local heat transfer coefficient for a circular disk facing a uniform oncoming flow. The experiments covered the range of Reynolds numbers Re from 5000 to 50,000 and were performed using the naphthalene sublimation technique. To complement the experiments, an analysis incorporating both potential flow theory and boundary layer theory was used to predict the stagnation point heat transfer. The measured average Nusselt numbers definitively resolved a deep disparity between information from the literature and yielded the correlation Nu = 1.05 Pr0.36 Re1/2. The radial distributions of the local heat transfer coefficient were found to be congruent when they were normalized by Re1/2. Furthermore, the radial profiles showed that the local coefficient takes on its minimum value at the stagnation point and increases with increasing radial distance from the center of the disk. At the outer edge of the disk, the coefficient is more than twice as large as that at the stagnation point. The theoretical predictions of the stagnation point heat transfer exceeded the experimental values by about 6 percent. This overprediction is similar to that which occurs for cylinders and spheres in crossflow.

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