Flow field characteristic and heat transfer performance in a channel with miniature square filament

2020 ◽  
Vol 163 ◽  
pp. 120433
Author(s):  
Yu Jiao ◽  
Jiansheng Wang ◽  
Xueling Liu
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Heat Transfer Performance ◽  
Transfer Performance ◽  
Field Characteristic

scholarly journals The Effect of Periodic Ribs on the Local Aerodynamic and Heat Transfer Performance of a Straight Cooling Channel

1996 ◽  
Author(s):  
G. Rau ◽  
M. Çakan ◽  
D. Moeller ◽  
T. Arts
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Heat Transfer Performance ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Hydraulic Diameter ◽  
Transfer Performance ◽  
Local Pressure ◽  
Reynolds Analogy ◽  
Law Of The Wall

The local aerodynamic and heat transfer performance were measured in a rib-roughened square duct as a function of the rib pitch to beight ratio. The blockage ratio of these square obstacles was 10% or 20% depending on whether they were placed on one single (1s) or on two opposite walls (2s). The Reynolds number, based on the channel mean velocity and hydraulic diameter, was fixed at 30000. The aerodynamic description of the flow field was based on local pressure distributions along the ribbed and adjacent smooth walls as well as on 2D LDV explorations in the channel symmetry plane and in two planes parallel to the ribbed wall(s). Local heat transfer distributions were obtained on the floor, between the ribs, and on the adjacent smooth side wall. Averaged parameters, such as friction factor and averaged heat transfer enhancement factor, were calculated from the local results and compared to correlations given in literature. This contribution showed that simple correlations derived from the law of the wall similarity and from the Reynolds analogy could not be applied for the present rib height-to-channel hydraulic diameter ratio (e/Dh=0.1). The strong secondary flows resulted in a three-dimensional flow field with high gradients in the local heat transfer distributions on the smooth side walls.

scholarly journals The Effect of Periodic Ribs on the Local Aerodynamic and Heat Transfer Performance of a Straight Cooling Channel

1998 ◽  
Vol 120 (2) ◽  
pp. 368-375 ◽  
Author(s):  
G. Rau ◽  
M. C¸akan ◽  
D. Moeller ◽  
T. Arts
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Heat Transfer Performance ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Hydraulic Diameter ◽  
Transfer Performance ◽  
Local Pressure ◽  
Reynolds Analogy ◽  
Law Of The Wall

The local aerodynamic and heat transfer performance were measured in a rib-roughened square duct as a function of the rib pitch to height ratio. The blockage ratio of these square obstacles was 10 or 20 percent depending on whether they were placed on one single (1s) or on two opposite walls (2s). The Reynolds number, based on the channel mean velocity and hydraulic diameter, was fixed at 30,000. The aerodynamic description of the flow field was based on local pressure distributions along the ribbed and adjacent smooth walls as well as on two-dimensional LDV explorations in the channel symmetry plane and in two planes parallel to the ribbed wall(s). Local heat transfer distributions were obtained on the floor, between the ribs, and on the adjacent smooth side wall. Averaged parameters, such as friction factor and averaged heat transfer enhancement factor, were calculated from the local results and compared to correlations given in literature. This contribution showed that simple correlations derived from the law of the wall similarity and from the Reynolds analogy could not be applied for the present rib height-to-channel hydraulic diameter ratio (e/Dh = 0.1). The strong secondary flows resulted in a three-dimensional flow field with high gradients in the local heat transfer distributions on the smooth side walls.

The Effects of Dimpled Surface Geometry on Heat Transfer in an Impinging Jet Flow

2002 ◽  
Author(s):  
Ann M. Anderson ◽  
David M. Chapin
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Heat Transfer Performance ◽  
Impinging Jet ◽  
Jet Flow ◽  
Surface Flow ◽  
Diameter Ratio ◽  
Transfer Performance ◽  
Surface Geometry ◽  
Actual Surface

The objective of this study was to characterize the heat transfer performance of a dimpled surface in an impinging jet flow field. Using a statistical design of experiments approach we designed 8 (23) test plates to study the effects of dimple spacing, dimple depth and dimple diameter and compared them to smooth plate heat transfer. The plates were placed opposite a square jet and tests were run for Reynolds numbers based on jet hydraulic diameter of 10,000 to 30,000 at a range of jet to plate spacings. Plate averaged heat transfer coefficients, based on actual surface area (including dimple area) were measured under steady state conditions. The results show that the dimple spacing to diameter ratio has the most significant effect on heat transfer performance at high velocities, while the dimple depth to diameter ratio is more significant at lower velocities. The effect of dimple diameter was found to be significant only under poor heat transfer conditions. Particle Image Velocimetry images of the dimple surface flow field showed enhanced entrainment at high velocities which may explain why the dimple spacing to diameter effect is more significant at high velocities.

Research on External Flow and Heat Transfer Characteristics of H-Type Fin Tube Based on Longitudinal Vortex

2014 ◽  
Vol 614 ◽  
pp. 133-137 ◽  
Author(s):  
Bo Jiang ◽  
Wei Dong Hao ◽  
Zhi Hong Hu ◽  
Fu Guo Liu
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Heat Transfer Performance ◽  
External Flow ◽  
Longitudinal Vortex ◽  
Transfer Performance ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Fin Tube

An H-type fin tube based on longitudinal vortex for boiler economizer is put forward in this paper, in order to solve the problem of too high temperature for denitration catalyst reaction for flue gas leaving the econonmizer. CFD method is adopted to study the external flow and heat transfer characteristics of the H-type fin tube based on longitudinal vortex, obtaining the flow field and temperature field distribution in the near wall region outside the fin tube. The results show that vortex flow in different degrees occurs in the rear flow field of the H-type fin tube based on longitudinal vortex, which introduces velocity component normal to main stream direction to the fluid of main flow zone, improves the synergy of temperature gradient field with velocity field and significantly enhances heat transfer performance of the fin tube. Within the parameter range studied in this paper, the 30° attack angle makes the best PEC value and correspondingly best comprehensive heat transfer performance.

Analysis of the heat transfer performance inside cavity of the counter rotating dual rotor bearing

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Fei Chen ◽  
Chao Wang ◽  
Ke Yan ◽  
Muhammad Azeem Ghouri ◽  
Yongsheng Zhu  ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Contact Zone ◽  
Heat Dissipation ◽  
Heat Transfer Performance ◽  
Outer Ring ◽  
Phase Flow ◽  
Transfer Performance ◽  
Content Type ◽  
Ring Rotation

Purpose This paper aims to analyze the temperature field and the heat transfer performance of the counter rotating dual rotor bearings (CRDRB) based on the air phase flow field at different speeds to provide effective support for the lubrication and the thermal design of CRDRB. Design/methodology/approach In this study, taking H7006C angular contact ball bearing as an example, based on the flow visualization technique and the thermal analysis methods, the effects of outer ring speed on the air phase flow field, the temperature field and the heat transfer in bearing cavity were investigated. Findings Results indicated that there were more complex turbulent air vortices in CRDRB cavity. Turbulent cyclones in critical contact zone reduced the heat dissipation capacity of air. Compared with single rotor bearing with a static outer ring, the average heat transfer coefficient reduced by 11.78% and the average temperature raised by 3.06 K inside CRDRB cavity. Under the influence of outer ring rotation, the high temperature area in ball-inner raceway contact zone and pocket raised and reduced by 160.13% and 30.48%, respectively. The outer ring rotation had opposite effect on the heat dissipation of raceway contact zone and pocket. Originality/value The air phase flow field characteristics and the heat transfer performance of CRDRB were revealed and analyzed from the mechanism. An area quantification method was presented as an auxiliary mean of the thermal analysis to evaluate the heat transfer performance of bearing.

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