Perforated Rib in Turbulent Boundary Layer

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Valery N. Afanasiev ◽  
Dehai Kong ◽  
S. A. Isaev
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Turbulent Boundary Layer ◽  
Separation Zone ◽  
Area Ratio ◽  
Open Area ◽  
Staggered Arrangement ◽  
Recirculation Zones ◽  
The Mean

Abstract This study presents the results of the experimental study on hydrodynamics and heat transfer in separation zone in front and behind a single rectangular perforated rib mounted on a flat plate. The effects of perforation open-area ratio (β = 12%, 23.5%, and 44%) and the location of the hole on the rib (at the bottom, at the top, and in a staggered arrangement) on the mean and fluctuating characteristics of the turbulent dynamic and thermal boundary layers in the median section of the plate were examined. It was established that the stagnant and recirculation zones in the front and behind the perforated rib were shifted and became smaller or disappeared.

scholarly journals Experimental study of the turbulent boundary layer in the presence of a rectangular perforated rib

2019 ◽  
Author(s):  
V.N. Afanasiev ◽  
Dehai Kong ◽  
S.I. Getya ◽  
V.L. Trifonov
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Experimental Study ◽  
Turbulent Boundary Layer ◽  
Gas Turbines ◽  
Jet Flows ◽  
Space Technology ◽  
Heat Transfer Efficiency ◽  
Mass Transfer Processes ◽  
Efficient Heat Transfer

Separated flows are widespread in many areas of science and technology, such as space technology, aviation, gas turbines, etc., which has a significant effect on the processes of hydrodynamics and heat transfer in them. The separation of the flow and its reattachment can serve as a powerful means of enhancing heat and mass transfer processes, and its organization is quite simple and reliable in terms of technology. This paper presents the results of the experimental study on hydrodynamics and heat transfer in the separation zone in front and behind a single rectangular perforated rib located on a flat plate heated by the law of qw = const. Experimental measurements were carried out using the Pitot-Prandtl tube and Dantec Dynamics hot-wire anemometry system, which allows us to obtain new characteristics of the turbulent boundary layer, both mean and oscillatory ones. We analyzed the influence of the perforation ratio of the rib and the location of the holes in the rib on the heat transfer efficiency. It was established that the stagnant and recirculation zones in front and behind the perforated rib were shifted and became smaller or disappeared. Findings of research show that jet flows, impinging on the heat transfer surface from the perforation holes, provide more efficient heat transfer behind the perforated rib, compared to that behind the solid rib.

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.

Rib in Turbulent Boundary Layer

2017 ◽  
pp. 13-35 ◽  
Author(s):  
V. N. Afanasiev ◽  
V. I. Trifonov ◽  
S. I. Getya ◽  
D. Kong
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Flat Plate ◽  
Strong Dependence ◽  
Experimental Studies ◽  
Practical Interest ◽  
Transfer Coefficients ◽  
Before And After ◽  
The Mean

Experimental and theoretical investigations of the flow structure, with the flow over a variety of protrusions and depressions on the initially smooth surfaces are of considerable practical interest, since the there are constructive or random occurring depressions and cavities found on many different convective surfaces. With the flow over the depressions and protrusions, the boundary layer separation and its reattachment can lead to occurring specific phenomena, which have a significant impact on drag and heat transfer. These phenomena, which are encountered in the course of experimental studies and obtaining adequate mathematical models, are complicated and hard-to-understand.The paper presents experimental results of hydrodynamics and heat transfer in the separation zone before and after a single rectangular rib and a round corner rib with the height of approximately y+ = 100, which are placed on the flat plate that is heated according to the law of qw=const. Experimental studies were conducted using a Pitot-Prandtl microprobe and a hot-wire Dantec Dynamics anemometry system, which allowed us to obtain both the mean and the fluctuating characteristics of the turbulent boundary layer and determine the boundaries of the vortex and separation zones.It is shown that the structure of vertex zones before and after the rib has a strong dependence on the rib shape and size. New experimental data on the mean and fluctuating characteristics in the turbulent boundary layer with the flow over the rectangular ribs with and without round top corners are obtained. Also, the fluctuations of temperature and especially velocity in the boundary layer after the rib are significantly higher than in the layer on the flat plate. The changing characteristic of the friction and heat transfer coefficients indicates that the increase of the heat transfer coefficient exceeds the growth of the friction coefficient after the ribs with the size 30 < y+ < 100.

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