scholarly journals Heat Transfer to the Highly Accelerated Turbulent Boundary Layer With and Without Mass Addition

1970 ◽  
Vol 92 (3) ◽  
pp. 499-505 ◽  
Author(s):  
W. M. Kays ◽  
R. J. Moffat ◽  
W. H. Thielbahr
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layers ◽  
Stanton Number ◽  
Temperature Profiles ◽  
Transfer Data ◽  
Experimental Heat ◽  
Prediction Scheme ◽  
Experimental Heat Transfer ◽  
Impermeable Wall

Experimental heat transfer data are presented for a series of asymptotic accelerated turbulent boundary layers for the case of an impermeable wall, and several cases of blowing, and suction. The data are presented as Stanton number versus enthalpy thickness Reynolds number. As noted by previous investigators, acceleration causes a depression in Stanton number when the wall is impermeable. Suction increases this effect, while blowing suppresses it. The combination of mild acceleration and strong blowing results in Stanton numbers which lie above the correlation for the same blowing but no acceleration. Velocity and temperature profiles are presented, from which it is possible to deduce explanations for the observed behavior of the Stanton number. A prediction scheme is proposed which is demonstrated to quite adequately reproduce the Stanton number results, using correlations derived from the profiles.

scholarly journals The Turbulent Boundary Layer on a Porous Plate: Experimental Heat Transfer with Uniform Blowing and Suction, with Moderately Strong Acceleration

1972 ◽  
Vol 94 (1) ◽  
pp. 111-118 ◽  
Author(s):  
W. H. Thielbahr ◽  
W. M. Kays ◽  
R. J. Moffat
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Porous Plate ◽  
Stanton Number ◽  
Graphical Form ◽  
Temperature Dependent ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Fluid Properties

Experimental data are presented for heat transfer to the turbulent boundary layer subjected to transpiration and acceleration at constant values of the acceleration parameter K = (ν/U∞2)(dU∞/dx) of approximately 1.45 × 10−6. This is a moderately strong acceleration, but not so strong as to result in laminarization of the boundary layer. The results for transpiration fractions F of −0.002, 0.0, and +0.0058 are presented in detail in tabular form, and in graphs of Stanton number versus enthalpy thickness Reynolds number. In addition, temperature profiles at several stations are presented. Stanton number results for F = −0.004, +0.002, and +0.004 are also presented, but in graphical form only. The data were obtained using air as both the free-stream and the transpired fluid, at relatively low velocities, and with temperature differences sufficiently low (approximately 40 deg F) that the influence of temperature-dependent fluid properties is minimal. All data were obtained with the surface maintained at a temperature invariant in the direction of flow.

Material design of a film cooling system using experimental heat transfer data

2012 ◽  
Vol 55 (21-22) ◽  
pp. 6278-6284 ◽  
Author(s):  
Kyung Min Kim ◽  
Jiwoon Song ◽  
Jun Su Park ◽  
Sanghoon Lee ◽  
Hyung Hee Cho
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Cooling System ◽  
Material Design ◽  
Transfer Data ◽  
Experimental Heat ◽  
Experimental Heat Transfer

Heat Transfer in the Turbulent Boundary Layer With a Step Change in Surface Roughness

1991 ◽  
Author(s):  
Robert P. Taylor ◽  
J. Keith Taylor ◽  
M. H. Hosni ◽  
Hugh W. Coleman
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Surface Roughness ◽  
Smooth Surface ◽  
Plate Boundary ◽  
Step Change ◽  
Stanton Number ◽  
Test Surface ◽  
Temperature Profiles ◽  
Boundary Layer Flows

Measurements of Stanton numbers, velocity profiles, temperature profiles, and turbulence intensity profiles are reported for turbulent flat plate boundary layer flows with a step change in surface roughness. The first 0.9 m length of the test surface is roughened with 1.27 mm diameter hemispheres spaced 2 base diameters apart in a staggered array. The remaining 1.5 m length is smooth. The experiments show that the step change from a rough to a smooth surface has a dramatic effect on the convective heat transfer. In many cases, the Stanton number drops below the smooth-wall correlation immediately downstream of the change in roughness. The Stanton number measurements are compared with predictions using the discrete element method with excellent results.

On free convection experiments in inclined air layers heated from below

1980 ◽  
Vol 96 (3) ◽  
pp. 461-479 ◽  
Author(s):  
Douglas W. Ruth ◽  
K. G. T. Hollands ◽  
G. D. Raithby
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Convective Motion ◽  
Secondary Transition ◽  
Transfer Data ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Air Layers ◽  
Rayleigh Numbers ◽  
Theory And Experiment

The heat transfer and free convective motion, in inclined air layers heated from below, for angles of incidence 0 [les ] ϕ [les ] 30°, and Rayleigh numbers 100 < Ra cos ϕ < 10000, are studied experimentally. Results of both heat-transfer measurements and flow-visualization studies are reported. The purpose of the study was to investigate the fact, first noted by Hollands et al. (1976), that the experimental heat-transfer data, for ϕ > 20°, is not a function of the product Ra cos ϕ only, as expected from theoretical consideration. This discrepancy between theory and experiment is here attributed to a hypothesized secondary transition in the convective motion, due primarily to perturbation velocities in the upslope direction. This secondary transition appears to be the same as that predicted theoretically by Clever & Busse (1977); qualitative agreement with their theory is observed.

Experimental Heat Transfer Investigation in a Multisplitter LP Vane Architecture

2010 ◽  
Author(s):  
V. Pinilla ◽  
J. P. Solano ◽  
G. Paniagua ◽  
S. Lavagnoli ◽  
T. Yasa
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Pressure Ratio ◽  
Transition To Turbulence ◽  
Time Resolved ◽  
Experimental Heat ◽  
Experimental Heat Transfer ◽  
Flow Features ◽  
Aero Engines ◽  
Layered Thin Film

This paper reports the external convective heat transfer in an innovative low pressure vane with multisplitter configuration. Three small aerodynamic blades are positioned between each structural vane, providing a novel architecture for ultra-high by-pass ratio aero-engines, with increased LP vane radius and swan-neck diffuser to link the HP turbine. The measurements have been performed in the compression tube test rig of the von Karman Institute, using single layered thin film gauges. Time-averaged and time-resolved heat transfer distributions are presented for the three aerovanes and for the structural blade, at three pressure ratios tested at representative conditions of modern aeroengines, with M2,is ranging from 0.87 to 1.07 and a Reynolds number of about 106. This facility is specially suited to control the gas-to-wall temperature ratio. Accurate time-averaged heat transfer distributions around the aerovanes are assessed, that allow characterizing the boundary layer status for each position and pressure ratio. The heat transfer distribution around the structural blade is also obtained, depicting clear transition to turbulence, as well as particular flow features on the pressure side, like separation bubbles. Unsteady data analysis reveals the destabilizing effect of the rotor left-running shock on the aerovanes boundary layer, as well as the shift of transition onset for different blade passing events.

Using Artificial Neural Networks to Develop a Predictive Method From Complex Experimental Heat Transfer Data

2001 ◽  
Author(s):  
Matthew D. Kelleher ◽  
Thomas J. Cronley ◽  
K. T. Yang ◽  
Mihir Sen
Keyword(s):  
Heat Transfer ◽  
Neural Networks ◽  
Artificial Neural Networks ◽  
Complex Situation ◽  
Transfer Data ◽  
Predictive Algorithm ◽  
Experimental Heat ◽  
Predictive Method ◽  
Experimental Heat Transfer ◽  
Artificial Neural

Abstract Artificial neural networks are employed to develop a predictive algorithm using experimental heat transfer data for a complex situation. The data of Marto and Anderson has used to illustrate the process. This data is from a series of experiments investigating the boiling heat transfer from a vertical bank of tubes in refrigerant 114 with variable amounts of oil present. Both finned and unfinned tubes were investigated. The network was trained with a partial set of the available data. The prediction obtained using the trained network was then compared to the remaining experimental data. The artificial neural network provided an excellent predictive method.

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