Study on local heat transfer enhancement technique for high pressure chamber

2006 ◽  
Author(s):  
Jianhua Chen ◽  
Guitian Zhang ◽  
Huiqiang Zhang ◽  
Lixin Zhou ◽  
Haibo Wu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Heat Transfer Enhancement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Pressure Chamber ◽  
High Pressure Chamber ◽  
Transfer Enhancement ◽  
Enhancement Technique

Heat Transfer Enhancement in Triangular Ducts With an Array of Side-Entry Wall/Impinged Jets

1999 ◽  
Author(s):  
J.-J. Hwang ◽  
C.-S. Cheng ◽  
Y.-P. Tsia
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Leading Edge ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Transfer Enhancement ◽  
Transfer Coefficients ◽  
Pressure Drops ◽  
Heat Transfer Coefficients ◽  
Inclined Angle

An experimental study has been performed to measure local heat transfer coefficients and static well pressure drops in leading-edge triangular ducts cooled by wall/impinged jets. Coolant provided by an array of equally spaced wall jets is aimed at the leading-edge apex and exits from the radial outlet. Detailed heat transfer coefficients are measured for the two walls forming the apex using transient liquid crystal technique. Secondary-flow structures are visualized to realize the mechanism of heat transfer enhancement by wall/impinged jets. Three right-triangular ducts of the same altitude and different apex angles of β = 30 deg (Duct A), 45 deg (Duct B) and 60 deg (Duct C) are tested for various jet Reynolds numbers (3000≦Rej≦12600) and jet spacings (s/d = 3.0 and 6.0). Results show that an increase in Rej increases the heat transfer on both walls. Local heat transfer on both walls gradually decreases downstream due to the crossflow effect. At the same Rej, the Duct C has the highest wall-averaged heat transfer because of the highest jet center velocity as well as the smallest jet inclined angle. Moreover, the distribution of static pressure drop based on the local through flow rate in the present triangular duct is similar to that that of developing straight pipe flows. Average jet Nusselt numbers on the both walls have been correlated with jet Reynolds number for three different duct shapes.

scholarly journals Heat Transfer Enhancement of Impingement Cooling by Adopting Circular-Ribs or Vortex Generators in the Wall Jet Region of A Round Impingement Jet

2020 ◽  
Vol 5 (3) ◽  
pp. 17 ◽  
Author(s):  
Ken-Ichiro Takeishi ◽  
Robert Krewinkel ◽  
Yutaka Oda ◽  
Yuichi Ichikawa
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Cooling System ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Vortex Generators ◽  
Wall Jet ◽  
Transfer Enhancement ◽  
Impingement Cooling ◽  
Impingement Jet

In the near future, when designing and using Double Wall Airfoils, which will be manufactured by 3D printers, the positional relationship between the impingement cooling nozzle and the heat transfer enhancement ribs on the target plate naturally becomes more accurate. Taking these circumstances into account, an experimental study was conducted to enhance the heat transfer of the wall jet region of a round impingement jet cooling system. This was done by installing circular ribs or vortex generators (VGs) in the impingement cooling wall jet region. The local heat transfer coefficient was measured using the naphthalene sublimation method, which utilizes the analogy between heat and mass transfer. As a result, it was clarified that, within the ranges of geometries and Reynolds numbers at which the experiments were conducted, it is possible to improve the averaged Nusselt number Nu up to 21% for circular ribs and up to 51% for VGs.

Numerical Investigation of Heat Transfer Enhancement on a Small Scale Vortex Generator

2009 ◽  
Author(s):  
Jiansheng Wang ◽  
Zhiqin Yang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Flow Structure ◽  
Rectangular Channel ◽  
Vortex Generator ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Vortex Generators ◽  
Small Scale ◽  
Transfer Enhancement

The heat transfer characteristic and flow structure of fluid in the rectangular channel with different height vortex generators in small scale are investigated with numerical simulation. Meantime, the properties of heat transfer and flow of fluid in the rectangular channel are compared with the channel which located small scale vortex generator. The variation law of local heat transfer and flow structure in channel is obtained. The mechanism of heat transfer enhancement of small scale vortex generators is discussed in detail. It is found that the influence of vortex generator on heat transfer is not in proportion to the size of vortex generator. What is more, turbulent flow structure near the wall, which influences the temperature distribution near the wall, induces the variety of local heat transfer. The fluid movement towards to the wall causes the heat transfer enhanced. On the contrary, the fluid movement away from the wall decreases the local heat transfer.

Heat Transfer Enhancement in Tip-Turn Region of Two-Pass Channel With a 180-Degree Turn

2011 ◽  
Author(s):  
Pavin Ganmol ◽  
Minking K. Chyu ◽  
Mary Anne Alvin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Internal Cooling ◽  
Transfer Enhancement ◽  
Sharp Turn ◽  
Pin Fins ◽  
Series Of Experiments ◽  
Turn Region

The design geometry and transport phenomena associated with the tip internal cooling can be very complex and has been little studied. Internal cooling channel near a tip region typically inherits a sharp, 180-degree, turn and little or no enhancement installation exists. To explore potential design for enhancement cooling, a series of experiments are performed to investigate the heat transfer enhancement by placing different pin-fins configurations in the tip-turn region of a two-pass channel with a 180-degree sharp turn. Transient liquid crystal technique is applied to acquire detailed local heat transfer data both on the channel surface and pin elements, for Reynolds number between 13,000 and 28,000. Present results suggest that the pin-fins can enhance heat transfer up to 2.3 fold in the tip-turn region and up to 1.3 fold for the entire channel. The presence of the pin-fins also changes the flow pattern in the post turn region which is resulting in more evenly distributed heat transfer downstream of the turn.

Heat Transfer Between Blockages With Holes in a Rectangular Channel

2003 ◽  
Vol 125 (4) ◽  
pp. 587-594 ◽  
Author(s):  
S. W. Moon ◽  
S. C. Lau
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Enhancement ◽  
Rectangular Channel ◽  
Local Heat Transfer ◽  
Reynolds Numbers ◽  
Local Heat ◽  
Hole Array ◽  
Transfer Enhancement ◽  
Large Pressure

Experiments have been conducted to study steady heat transfer between two blockages with holes and pressure drop across the blockages, for turbulent flow in a rectangular channel. Average heat transfer coefficient and local heat transfer distribution on one of the channel walls between two blockages, and overall pressure drop across the blockages were obtained, for nine different staggered arrays of holes in the blockages and Reynolds numbers of 10,000 and 30,000. For the hole configurations studied, the blockages enhanced heat transfer by 4.6 to 8.1 times, but significantly increased the pressure drop. Smaller holes in the blockages caused higher heat transfer enhancement, but larger increase of the pressure drop than larger holes. The heat transfer enhancement was lower in the higher Reynolds number cases. Because of the large pressure drop, the heat transfer per unit pumping power was lower with the blockages than without the blockages. The local heat transfer was lower nearer the upstream blockage, the highest near the downstream blockage, and also relatively high in regions of reattachment of the jets leaving the upstream holes. The local heat transfer distribution was strongly dependent on the configuration of the hole array in the blockages. A third upstream blockage lowered both the heat transfer and the pressure drop, and significantly changed the local heat transfer distribution.

Comparison of Wing-Type Vortex Generators for Heat Transfer Enhancement in Channel Flows

1994 ◽  
Vol 116 (4) ◽  
pp. 880-885 ◽  
Author(s):  
St. Tiggelbeck ◽  
N. K. Mitra ◽  
M. Fiebig
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Delta Wing ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Vortex Generators ◽  
Transfer Enhancement ◽  
Transfer Coefficients ◽  
Number Range ◽  
Longitudinal Vortices

Longitudinal vortices can be generated in a channel flow by punching or mounting small triangular or rectangular pieces on the channel wall. Depending on their forms, these vortex generators (VG) are called delta wing, rectangular wing, pair of delta winglets, and pair of rectangular winglets. The heat transfer enhancement and the flow losses incurred by these four basic forms of VGs have been measured and compared in the Reynolds number range of 2000 to 9000 and for angles of attack between 30 and 90 deg. Local heat transfer coefficients on the wall have been measured by liquid crystal thermography. Results show that winglets perform better than wings and a pair of delta winglets can enhance heat transfer by 46 percent at Re=2000 to 120 percent at Re=8000 over the heat transfer on a plate.

The Influence of Flexible Strip Height on Convective Heat Transfer Enhancement

2019 ◽  
Author(s):  
Yang Yang ◽  
David S.-K. Ting ◽  
Steve Ray
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Convective Heat ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Vortical Flow ◽  
Transfer Enhancement ◽  
Local Flow ◽  
Convective Heat Transfer Enhancement

Abstract A 12.7 mm wide flexible rectangular strip, made from 0.1 mm-thick aluminum sheet, is experimentally explored as a vortical flow generator for promoting heat convection from a flat plate in a wind tunnel. The strip is positioned normal to the freestream with an incoming velocity of 10 m/s, resulting in a Reynolds number, based on the strip width, of 8,500. The influence of the height of the flexible strip on the convective heat transfer enhancement is of interest. Three strip heights, 25.4 mm, 38.1 mm and 50.8 mm, were investigated. The heat transfer results are expressed in terms of Nusselt number, Nu, normalized by the unperturbed reference Nu0. The shortest, 25.4 mm high flexible strip resulted in the highest peak and overall heat transfer enhancement. The distribution of the local heat transfer enhancement is found to correlate well with the turbulent flow motion detailed using a triple-sensor hot-wire anemometer. Pointedly, the heat transfer rate is most elevated when the local flow is moving toward the hot plate, sweeping across a stretch of the surface before moving away from it. These effective convective motions are most effectively generated by the vortices produced by the shortest strip.

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