Experiments on the Onset of Longitudinal Vortices in Horizontal Blasius Flow Heated from Below

1978 ◽  
Vol 100 (1) ◽  
pp. 71-77 ◽  
Author(s):  
R. R. Gilpin ◽  
H. Imura ◽  
K. C. Cheng
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Surface Temperature ◽  
Flat Plate ◽  
Transfer Rate ◽  
Thermal Instability ◽  
Transition Process ◽  
Temperature Profiles ◽  
Longitudinal Vortices ◽  
Turbulent Transition

Experiments were performed to confirm the occurrence and growth of longitudinal vortices in a laminar boundary layer developing in water over a heated horizontal flat plate with uniform surface temperature. Photographs of the vortices, measurements of the conditions of their onset, and measurements of their wavelength are presented. Comparisons are made with theoretical instability results for the critical Grashof number and wavelength. Temperature profiles across the boundary layer were measured for flows with and without vortices to show qualitatively the effect that the longitudinal vortices have on the heat transfer rate at the plate. Under conditions of thermal instability the longitudinal vortices were found to be the first stage of the laminar-turbulent transition process in a boundary layer heated from below.

Coupled Heat Transfer Simulations of Air-Cooled Turbines with an Algebraic Transition Model

2012 ◽  
Vol 455-456 ◽  
pp. 1153-1159
Author(s):  
Qiang Wang ◽  
Zhao Yuan Guo ◽  
Guo Tai Feng
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Thermal Load ◽  
Transition Process ◽  
Test Case ◽  
Transition Model ◽  
High Pressure Turbine ◽  
Coupled Heat Transfer ◽  
Turbulent Transition ◽  
Turbine Vane

The investigation was to study the effect of laminar-turbulent transition on predicting thermal load of vane. The Abu-Ghannam and Shaw (AGS) algebraic transition model was applied in the coupled solver, HIT3D. Then the solver was employed to carry out coupled heat transfer simulations, and the test case was 5411 run of NASA0-MARKⅡ vane, a high-pressure turbine vane. The results shown that AGS model was able to predict the transition process in the boundary layer near the vane, and that the simulation with such model leads to thermal load agreeing well the measured one. Then the developed solver was applied to predict a low-pressure vane, and the results shown that CHT simulation with full turbulence model would predict higher thermal load than that with transition model.

Longitudinal vortices in a laminar natural convection boundary layer flow on an inclined flat plate and their influence on heat transfer

2001 ◽  
Vol 432 ◽  
pp. 313-339 ◽  
Author(s):  
PETER JESCHKE ◽  
HANS BEER
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Natural Convection ◽  
Flat Plate ◽  
Wide Band ◽  
Constant Heat Flux ◽  
Convection Flow ◽  
Convection Boundary Layer ◽  
Full Field ◽  
Longitudinal Vortices

The linear and nonlinear growth of longitudinal vortices in a laminar boundary layer and the development of secondary instabilities are investigated theoretically and by experiment. As a prototype problem the natural convection flow along a constant-heat-flux inclined flat plate in water is chosen. Based upon the smallness of the plate's angle of inclination from the vertical, the largeness of the Grashof number, and the smallness of the vortex strength, a perturbation method is used to derive and solve a consistent set of governing equations for the linear, weakly nonlinear and the strongly nonlinear regimes which is asymptotically correct to first order. Liquid-crystal thermography based on wide-band liquid crystals is used to provide full-field, highly accurate wall temperature measurements and visualizations.The spanwise periodic thickening and thinning of the boundary layer through a nonlinear, but steady, vortex growth is seen to be responsible for practically all of the increase of mean heat transfer values during the laminar–turbulent transition. Secondary instabilties in the form of sinuous and varicose unsteady wave modes and the steady merging of vortices are visualized but are seen to have only a minor additional influence on mean heat transfer.

Experimental study of heat transfer in the boundary layer of a flat plate with the impact of weak shock waves on the leading edge

2020 ◽  
Author(s):  
V. L. Kocharin ◽  
A. A. Yatskikh ◽  
D. S. Prishchepova ◽  
A. V. Panina ◽  
Yu. G. Yermolaev ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Shock Waves ◽  
Flat Plate ◽  
Leading Edge ◽  
Weak Shock ◽  
The Impact

scholarly journals Experimental study of the impact of N-wave on heat transfer in a boundary layer of a flat plate at the Mach number 2

2021 ◽  
Author(s):  
V. L. Kocharin ◽  
A. A. Yatskikh ◽  
D. S. Prishchepova ◽  
A. V. Panina ◽  
Yu. G. Yermolaev ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Mach Number ◽  
Flat Plate ◽  
N Wave ◽  
The Impact

Skin friction and surface temperature of an insulated flat plate fixed in a fluctuating stream

1971 ◽  
Vol 46 (1) ◽  
pp. 165-175 ◽  
Author(s):  
Hiroshi Ishigaki
Keyword(s):  
Boundary Layer ◽  
Surface Temperature ◽  
Flat Plate ◽  
Skin Friction ◽  
High Frequency ◽  
Energy Equation ◽  
Oscillation Amplitude ◽  
Flow Oscillation ◽  
Velocity Amplitude ◽  
The Mean

The time-mean skin friction of the laminar boundary layer on a flat plate which is fixed at zero incidence in a fluctuating stream is investigated analytically. Flow oscillation amplitude outside the boundary layer is assumed constant along the surface. First, the small velocity-amplitude case is treated, and approximate formulae are obtained in the extreme cases when the frequency is low and high. Next, the finite velocity-amplitude case is treated under the condition of high frequency, and it is found that the formula obtained for the small-amplitude and high-frequency case is also valid. These results show that the increase of the mean skin friction reduces with frequency and is ultimately inversely proportional to the square of frequency.The corresponding energy equation is also studied simultaneously under the condition of zero heat transfer between the fluid and the surface. It is confirmed that the time-mean surface temperature increases with frequency and tends to be proportional to the square root of frequency. Moreover, it is shown that the timemean recovery factor can be several times as large as that without flow oscillation.

DNS study on turbulent heat transfer induced by virtual turbulence at inlet in boundary layer on a flat plate

2020 ◽  
Vol 2020 (0) ◽  
pp. 0125
Author(s):  
Hirofumi HATTORI ◽  
Keita KANO ◽  
Haruka TADANO ◽  
Tomoya HOURA ◽  
Masato TAGAWA
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Flat Plate ◽  
Turbulent Heat Transfer ◽  
Turbulent Heat
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