Heat Transfer in the Separated and Reattached Flow on a Blunt Flat Plate

1974 ◽  
Vol 96 (4) ◽  
pp. 459-462 ◽  
Author(s):  
Terukazu Ota ◽  
Nobuhiko Kon
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Leading Edge ◽  
Two Dimensional ◽  
Separated And Reattached Flow ◽  
The Heat Transfer Coefficient ◽  
Blunt Leading Edge ◽  
Made In

Heat transfer measurements are made in the separated, reattached, and redeveloped regions of the two-dimensional air flow on a flat plate with blunt leading edge. The flow reattachment occurs at about four plate thicknesses downstream from the leading edge and the heat transfer coefficient becomes maximum at that point and this is independent of the Reynolds number which ranged from 2720 to 17900 in this investigation. The heat transfer coefficient is found to increase sharply near the leading edge. The development of flow is shown through the measurements of the velocity and temperature in the separated, reattached, and redeveloped regions.

Wind-Related Heat Transfer Coefficient for Flat-Plate Solar Collectors

1987 ◽  
Vol 109 (2) ◽  
pp. 108-110 ◽  
Author(s):  
S. Shakerin
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Separation Bubble ◽  
Convective Heat Transfer Coefficient ◽  
Leading Edge ◽  
The Heat Transfer Coefficient ◽  
Good Agreement

Experiments were performed to evaluate the convective heat transfer coefficient for a flat plate mounted in a wooden model of a roof of a building. The experiments were carried out in a closed-circuit wind tunnel and included parametric adjustments of the roof tilt and Reynolds number, based on the length of the plate. The roof tilt was set at 0, 30, 45, 60, and 90 degrees and the Reynolds number ranged from 58,000 to 250,000. A transient, one lump, thermal approach was used for heat transfer calculations. Due to a separation bubble at the leading edge of the model, i.e., the roof, at angles of attack of less than 40 degrees, the flow became turbulent after reattachment. This resulted in a higher heat transfer than previously reported in the literature. At higher angles of attack, the flow was not separated at the leading edge and remained laminar. The heat transfer coefficient for higher angles of attack, i.e., α > 40 deg, was found to be approximately independent of the angle of attack and in good agreement with the previously published results.

Nanoparticle aggregation kinematics on the quadratic convective magnetohydrodynamic flow of nanomaterial past an inclined flat plate with sensitivity analysis

2021 ◽  
pp. 095440892110562
Author(s):  
AS Sabu ◽  
Joby Mackolil ◽  
B Mahanthesh ◽  
Alphonsa Mathew
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Sensitivity Analysis ◽  
Heat Transfer Coefficient ◽  
Heat Source ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Inclined Plate ◽  
The Impact ◽  
The Heat Transfer Coefficient

The study focuses on the aggregation kinematics in the quadratic convective magneto-hydrodynamics of ethylene glycol-titania ([Formula: see text]) nanofluid flowing through an inclined flat plate. The modified Krieger-Dougherty and Maxwell-Bruggeman models are used for the effective viscosity and thermal conductivity to account for the aggregation aspect. The effects of an exponential space-dependent heat source and thermal radiation are incorporated. The impact of pertinent parameters on the heat transfer coefficient is explored by using the Response Surface Methodology and Sensitivity Analysis. The effects of several parameters on the skin friction and heat transfer coefficient at the plate are displayed via surface graphs. The velocity and thermal profiles are compared for two physical scenarios: flow over a vertical plate and flow over an inclined plate. The nonlinear problem is solved using the Runge–Kutta-based shooting technique. It was found that the velocity profile significantly decreased as the inclination of the plate increased on the other hand the temperature profile improved. The heat transfer coefficient decreased due to the increase in the Hartmann number. The exponential heat source has a decreasing effect on the heat flux and the angle of inclination is more sensitive to the heat transfer coefficient than other variables. Further, when radiation is incremented, the sensitivity of the heat flux toward the inclination angle augments at the rate 0.5094% and the sensitivity toward the exponential heat source augments at the rate 0.0925%. In addition, 41.1388% decrement in wall shear stress is observed when the plate inclination is incremented from [Formula: see text] to [Formula: see text].

Inverse BEM Method to Identify Surface Temperatures and Heat Transfer Coefficient Distributions at Inaccessible Surfaces

2005 ◽  
Author(s):  
Alain J. Kassab ◽  
Eduardo A. Divo ◽  
Minking K. Chyu ◽  
Frank J. Cunha
Keyword(s):  
Heat Transfer ◽  
Inverse Problem ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Field Variable ◽  
Quadratic Functional ◽  
Two Dimensional ◽  
Additional Information ◽  
Coefficient Distribution ◽  
The Heat Transfer Coefficient

The purpose of the inverse problem considered in this study is to resolve heat transfer coefficient distributions by solving a steady-state inverse problem. Temperature measurements at interior locations supply the additional information that renders the inverse problem solvable. A regularized quadratic functional is defined to measure the deviation of computed temperatures from the values under current estimates of the heat transfer coefficient distribution at the surface exposed to convective heat transfer. The inverse problem is solved by minimizing this functional using a parallelized genetic algorithm (PGA) as the minimization algorithm and a two-dimensional multi-region boundary element method (BEM) heat conduction code as the field variable solver. Results are presented for a regular rectangular geometry and an irregular geometry representative of a blade trailing edge and demonstrate the success of the approach in retrieving accurate heat transfer coefficient distributions.

Investigation on the Leading Edge Film Cooling of Counter-Inclined Cylindrical and Laid-Back Holes With and Without Impingement: Part II — Heat Transfer Coefficient

2018 ◽  
Author(s):  
Rui-dong Wang ◽  
Cun-liang Liu ◽  
Hai-yong Liu ◽  
Hui-ren Zhu ◽  
Qi-ling Guo ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Leading Edge ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
The Heat Transfer Coefficient ◽  
Tube Structure

Heat transfer of the counter-inclined cylindrical and laid-back holes with and without impingement on the turbine vane leading edge model are investigated in this paper. To obtain the film cooling effectiveness and heat transfer coefficient, transient temperature measurement technique on complete surface based on double thermochromic liquid crystals is used in this research. A semi-cylinder model is used to model the vane leading edge which is arranged with two rows of holes. Four test models are measured under four blowing ratios including cylindrical film holes with and without impingement tube structure, laid-back film holes with and without impingement tube structure. This is the second part of a two-part paper, the first part paper GT2018-76061 focuses on film cooling effectiveness and this study will focus on heat transfer. Contours of surface heat transfer coefficient and laterally averaged result are presented in this paper. The result shows that the heat transfer coefficient on the surface of the leading edge is enhanced with the increase of blowing ratio for same structure. The shape of the high heat transfer coefficient region gradually inclines to span-wise direction as the blowing ratio increases. Heat transfer coefficient in the region where the jet core flows through is relatively lower, while in the jet edge region the heat transfer coefficient is relatively higher. Compared with cylindrical hole, laid-back holes give higher heat transfer coefficient. Meanwhile, the introduction of impingement also makes heat transfer coefficient higher compared with cross flow air intake. It is found that the heat transfer of the combination of laid-back hole and impingement tube can be very high under large blowing ratio which should get attention in the design process.

scholarly journals Modeling Film-Coolant Flow Characteristics at the Exit of Shower-Head Holes

2000 ◽  
Author(s):  
Vijay K. Garg
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Leading Edge ◽  
Coolant Flow ◽  
The Heat Transfer Coefficient

Abstract The coolant flow characteristics at the hole exits of a film-cooled blade are derived from an earlier analysis where the hole pipes and coolant plenum were also discretized. The blade chosen is the VKI rotor with three staggered rows of shower-head holes. The present analysis applies these flow characteristics at the shower-head hole exits. A multi-block three-dimensional Navier-Stokes code with Wilcox’s k-ω model is used to compute the heat transfer coefficient on the film-cooled turbine blade. A reasonably good comparison with the experimental data as well as with the more complete earlier analysis where the hole pipes and coolant plenum were also gridded is obtained. If the 1/7th power law is assumed for the coolant flow characteristics at the hole exits, considerable differences in the heat transfer coefficient on the blade surface, specially in the leading-edge region, are observed even though the span-averaged values of h match well with the experimental data. This calls for span-resolved experimental data near film-cooling holes on a blade for better validation of the code.

scholarly journals The Effect of Density Ratio on the Heat Transfer Coefficient From a Film Cooled Flat Plate

1989 ◽  
Author(s):  
H. D. Ammari ◽  
N. Hay ◽  
D. Lampard
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Flat Plate ◽  
Strong Dependence ◽  
Density Ratio ◽  
Polymer Surface ◽  
Operating Conditions ◽  
Density Ratios ◽  
The Heat Transfer Coefficient

The effect of density ratio of cooling films on the heat transfer coefficient on a flat plate is investigated using a heat-mass transfer analogy. The experimental technique employed uses a swollen polymer surface and laser holographic interferometry. A density ratio of 1.0 was achieved using air as the injectant. Density ratios of 1.38 and 1.52, representative of turbine operating conditions, were obtained by using foreign gases. The coolant fluids were injected at various blowing rates through a single normal hole or through a row of holes spaced at three-diameter intervals, and inclined at 35° or 90° to the mainstream direction. The experiments were conducted under isothermal conditions in a subsonic, zero mainstream pressure gradient turbulent boundary layer. The results indicated large differences in behaviour between the two injection angles. For normal injection, the heat transfer coefficient at a fixed blowing parameter was insensitive to the variation of density ratio, whereas for 35° injection strong dependence was observed. Scaling parameters for the heat transfer data have been proposed so that use can be made of data obtained at density ratios not representative of gas turbine practice. In addition, a correlation for normal injection data has been formulated.

Conjugate heat transfer from surface-mounted finite blunt plates

2006 ◽  
Vol 220 (1) ◽  
pp. 83-94 ◽  
Author(s):  
M Yaghoubi ◽  
E Velayati
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Three Dimensional ◽  
Leading Edge ◽  
Fin Efficiency ◽  
Flow And Heat Transfer ◽  
Flow Reynolds Number ◽  
The Heat Transfer Coefficient

Numerical studies of fluid flow and heat transfer are made in the separated, reattached, and redeveloped regions of the three-dimensional air flow on an array of finite plates with blunt leading edge. The flow reattachment occurs at a place downstream from the leading edge and the heat transfer coefficient becomes maximum around this region. The heat transfer coefficient is found to increase sharply near the leading edge and reduces in the wake. For the range of the parameters investigated in this study, some correlations have been developed for the length of reattachment region and variation of overall heat transfer coefficient for the considered bluff obstacles with various geometry and flow Reynolds number. For such blunt plates, when they are acting like fins, fin efficiency is determined and a relation based on flow Reynolds number and geometric parameters is developed to predict variation of the overall fin efficiency.

Heat Transfer and Effectiveness for a Turbulent Boundary Layer With Tangential Fluid Injection

1960 ◽  
Vol 82 (4) ◽  
pp. 303-312 ◽  
Author(s):  
R. A. Seban
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Free Stream ◽  
Cooling System ◽  
Leading Edge ◽  
Free Stream Velocity ◽  
Stream Velocity ◽  
The Heat Transfer Coefficient

Experimental results are presented for the effectiveness and for the heat-transfer coefficient for a film cooling system in which air was used both for the film and for the free-stream fluids. Injection occurred at a single tangential slot near the leading edge of the plate and the slot size was varied. All flows were turbulent and the injection velocities covered a range from much less to much greater than the free-stream velocity. Correlations are realized for both the effectiveness and for the heat-transfer coefficient and, as in the past experience with such systems, separate specifications are needed for injection velocities greater and less than the free-stream velocity.

Sign in / Sign up

Export Citation Format

Share Document