Short Duration Heat Transfer Studies at High Free-Stream Temperatures

1982 ◽  
Author(s):  
D. M. Kercher ◽  
R. E. Sheer ◽  
R. M. C. So
Keyword(s):  
Heat Transfer ◽  
Shock Tube ◽  
Flat Plate ◽  
Short Duration ◽  
Free Stream ◽  
Convex Surface ◽  
Surface Heat ◽  
Shock Tunnel ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

This paper describes short duration heat transfer measurements on a flat plate and a gas turbine nozzle airfoil at high free-stream temperatures. A shock tube generated the high temperature and pressure air flow. Thin-film heat gages recorded the surface heat flux. The flat plate was tested both in the shock tube and in a shock tunnel placed aft of the tube. Shock tunnel tests on the nozzle airfoil measured the local heat transfer distribution. The flat plate free-stream temperatures varied from 830 °R (460 K) to 3190 °R (1770 K) for a Tw/TT,g temperature ratio of 0.17 to 0.64 at Mach numbers from 0.12 to 1.34. The nozzle measurements at a Tw/TT,g of 0.35 to 0.39 generally indicate that pressure (concave) surface heat transfer coefficients are high, whereas the suction (convex) surface shows much lower heat transfer coefficients than a turbulent flat plate correlation.

Short Duration Heat Transfer Studies at High Free-Stream Temperatures

1983 ◽  
Vol 105 (1) ◽  
pp. 156-166 ◽  
Author(s):  
D. M. Kercher ◽  
R. E. Sheer ◽  
R. M. C. So
Keyword(s):  
Heat Transfer ◽  
Shock Tube ◽  
Flat Plate ◽  
Short Duration ◽  
Free Stream ◽  
Convex Surface ◽  
Surface Heat ◽  
Shock Tunnel ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients

This paper describes short duration heat transfer measurements on a flat plate and a gas turbine nozzle airfoil at high free-stream temperatures. A shock tube generated the high-temperature and pressure air flow. Thin-film heat gages recorded the surface heat flux. The flat plate was tested both in the shock tube and in a shock tunnel placed aft of the tube. Shock tunnel tests on the nozzle airfoil measured the local heat transfer distribution. The flat plate free-stream temperatures varied from 830°R (460 K) to 3190°R (1770 K) for a Tw/TT, g temperature ratio of 0.17 to 0.64 at Mach numbers from 0.12 to 1.34. The nozzle measurements at a Tw/TT, g of 0.35 to 0.39 generally indicate that pressure (concave) surface heat transfer coefficients are high, whereas the suction (convex) surface shows much lower heat transfer coefficients than a turbulent flat-plate correlation.

A New Experimental Technique for Measuring Surface Heat Transfer Coefficients Using Uncalibrated Liquid Crystals

1999 ◽  
Author(s):  
Wayne N. O. Turnbull ◽  
Patrick H. Oosthuizen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Experimental Technique ◽  
Surface Heat Flux ◽  
Local Heat ◽  
Surface Heat ◽  
Phase Delay ◽  
Transfer Coefficients ◽  
Periodic Surface ◽  
Heat Transfer Coefficients

Abstract A new experimental technique has been developed that permits the determination of local surface heat transfer coefficients on surfaces without requirement for calibration of the temperature-sensing device. The technique uses the phase delay that develops between the surface temperature response and an imposed periodic surface heat flux. This phase delay is dependent upon the thermophysical properties of the model, the heat flux driving frequency and the local heat transfer coefficient. It is not a function of magnitude of the local heat flux. Since only phase differences are being measured there is no requirement to calibrate the temperature sensor, in this instance a thermochromic liquid crystal. Application of a periodic surface heat flux to a flat plate resulted in a surface colour response that was a function of time. This response was captured using a standard colour CCD camera and the phase delay angles were determined using Fourier analysis. Only the 8 bit G component of the captured RGB signal was required, there being no need to determine a Hue value. From these experimentally obtained phase delay angles it was possible to determine heat transfer coefficients that compared well with those predicted using a standard correlation.

Heat Transfer and Pressure Distribution in Open Cavity Flow

1967 ◽  
Vol 89 (1) ◽  
pp. 103-108 ◽  
Author(s):  
A. F. Emery ◽  
J. A. Sadunas ◽  
M. Loll
Keyword(s):  
Heat Transfer ◽  
Pressure Distribution ◽  
Flat Plate ◽  
Cavity Flow ◽  
Rectangular Cavity ◽  
Open Cavity ◽  
Transfer Coefficients ◽  
Transient Techniques ◽  
Heat Transfer Coefficients ◽  
Mach 3

The heat transfer and pressure distribution in a rectangular cavity in a Mach 3 flow were investigated for a rectangular and an inverted-wedge recompression step. Noticeable differences between the results for the two steps were found in the recovery factors, but no real differences were detected in the heat-transfer coefficients or the velocity profiles. Heat-transfer coefficients in the cavity were determined by transient techniques and were found to range from 50 to 110 percent of the flat-plate value just prior to the expansion step.

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