Velocity, Temperature, and Heat-Transfer Measurements in a Turbulent Boundary Layer Downstream of a Stepwise Discontinuity in Wall Temperature

1957 ◽  
Vol 24 (1) ◽  
pp. 2-8
Author(s):  
D. S. Johnson
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Free Stream ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Velocity Fields ◽  
Temperature Fields ◽  
Mean Velocity ◽  
The Mean

Abstract Results are presented of an experimental investigation of the concomitant thermal and velocity fields occurring when there is a small stepwise discontinuity in the temperature of the wall on which a zero-pressure-gradient, low-speed, turbulent boundary layer has formed. The mean velocity and temperature fields have been measured and local heat-transfer-coefficient values in the stream-wise direction have been obtained in the region where the thermal boundary layer has not yet reached the free stream. No over-all similarity between the thermal and velocity fields was found.

Heat Transfer in the Oscillating Turbulent Boundary Layer

1969 ◽  
Vol 91 (4) ◽  
pp. 239-244 ◽  
Author(s):  
James A. Miller
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Coefficients ◽  
Mean Velocity ◽  
Heat Transfer Coefficients ◽  
Nusselt Numbers ◽  
Local Coefficients

Measurements of local heat-transfer coefficients in the fully established oscillating turbulent boundary layer over a flat plate are reported. In the range of frequencies from 0.1 to 200 cps and amplitudes from 8 to 92 percent of the freestream mean velocity, increases in local Nusselt numbers of 3 to 5 percent were found. It is concluded that substantial increases in local coefficients, sometimes reported in oscillating flows of low standing wave ratio, may be traced to reduced transition Reynolds numbers.

scholarly journals Heat Transfer in the Oscillating Turbulent Boundary Layer

1969 ◽  
Author(s):  
J. A. Miller
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Coefficients ◽  
Mean Velocity ◽  
Heat Transfer Coefficients ◽  
Nusselt Numbers ◽  
Local Coefficients

Measurements of local heat transfer coefficients in the fully established oscillating turbulent boundary layer over a flat plate are reported. In the range of frequencies from 0.1 to 200 cps and amplitudes from 8 to 92 percent of the freestream mean velocity increases in local Nusselt numbers of 3 to 5 percent were found. It is concluded that substantial increases in local coefficients sometimes reported in oscillating flows of low standing wave ratio may be traced to reduced transition Reynolds numbers.

Heat Transfer With Very High Free-Stream Turbulence: Part I—Experimental Data

1992 ◽  
Vol 114 (4) ◽  
pp. 827-833 ◽  
Author(s):  
P. K. Maciejewski ◽  
R. J. Moffat
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Free Stream ◽  
Turbine Blades ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Mean Velocity ◽  
Free Stream Turbulence ◽  
Free Jet ◽  
Very High

The present research investigates boundary layer heat transfer with very high freestream turbulence, a problem of primary interest in the gas turbine industry where existing boundary layer correlations and codes underpredict local heat transfer rates on first-stage turbine blades and vanes by as much as a factor of three for some engine designs. The problem was studied experimentally by placing a constant-temperature heat transfer surface at various locations in the margin of a turbulent free jet and measuring both the surface heat transfer rate and the turbulence in the free stream. In this experiment, free-stream turbulent fluctuations 20 to 60 percent relative to the mean velocity augment heat transfer 1.8 to 4 times that which would be predicted locally using accepted correlations for turbulent boundary layers at the same Reynolds number.

The Influence of Free Stream Turbulence on the Local Heat Transfer From Cylinders

1960 ◽  
Vol 82 (2) ◽  
pp. 101-107 ◽  
Author(s):  
R. A. Seban
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Free Stream ◽  
Separated Flow ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Turbulent Intensity ◽  
Transfer Coefficients ◽  
Free Stream Turbulence ◽  
Heat Transfer Coefficients

Local heat-transfer coefficients and recovery factors are presented for three different cylinders in a two-dimensional subsonic air flow, with emphasis on the effect of screen-produced turbulence on these quantities. The increase in turbulent intensity so realized produced larger local heat-transfer coefficients, in a way dependent upon the location on the cylinders, through a direct increase in the heat transfer to the laminar boundary layer, through an earlier transition to turbulence, or through an alteration in the character of the separated flow. Alternatively, recovery factors were affected less, being invariant with respect to the turbulent intensity for attached boundary layer flow, but demonstrating large changes in those separated flow regions for which increased free stream turbulence produced substantial changes in the nature of the separated flow.

Effect of Turbulence on the Heat Transfer in a Laminar and Turbulent Boundary Layer Over a Gas Turbine Blade

1982 ◽  
Author(s):  
V. Krishnamoorthy
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Transfer Coefficient ◽  
Turbulent Boundary Layer ◽  
Transfer Coefficient ◽  
Turbine Blade ◽  
Turbulence Intensity ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Turbulence Generator

This paper describes the results of the systematic investigations undertaken to identify the effect of free stream turbulence intensity on the local heat transfer coefficient distribution in the laminar and turbulent boundary layer present over a turbine blade profile in a two-dimensional cascade. The local heat-transfer coefficient was measured under constant heat flux boundary condition. Experiments were conducted at exit Reynolds numbers (based on blade chord) Rc = 2, 4.5 × 105 and at turbulence intensities εi up to 21.3 percent. A novel type of turbulence generator was used, with which it was possible to vary the turbulence intensity in the plane of the cascade without changing the distance between the turbulence generator and the cascade and without significantly varying the integral length scale of the turbulence.

Sign in / Sign up

Export Citation Format

Share Document