Research on Cooling Method in Surfacing Repair Process of Aero Compressor Blade

For the cooling method in surfacing repairing, most of the research focuses on the method based on the fixture structure. However, due to the low thermal conductivity and ultrathin alloy blade, the heat transfer speed from the molten pool to fixture is slow. When the heat is transferred to the fixture, most of the molten pool has solidified and absorbed or segregated out some impurities. Therefore, how to cool the welding area directly is more critical. For this reason, the thermal cycle characteristics of typical points of the blade and the heat transfer process of the key area of the fixture are analyzed, the original cooling time is calculated, and two innovative cooling methods based on lateral forced convection cooling and vertical jet impact forced convection cooling are proposed. For lateral forced cooling, with “AF-field” lateral convection cooling modeling, the cooling effects of characteristic points and sections under different flow velocities are calculated. For vertical jet impact cooling, the pressure, flow rate, and convective heat flux distribution on the wall under different impact heights and nozzle diameter are calculated. The influence of different inlet flow rates on cooling performance is influenced, based on the analysis results of impact modeling, the moving heat sink model is established, and the cooling effect under different heat sink-source distances is calculated. The heat transfer rules of two methods are analyzed in detail through modeling and simulations. The results show that both methods can improve the cooling effect and the vertical jet impact cooling method has an effect that is more obvious. When the nozzle radius is 2 mm, the impact height is 4d, the inlet flow velocity is 35 m/s, and the distance is 7 mm, and the cooling time under the vertical jet impact method is shortened by 12.5%, which can achieve better cooling effect. The experiment further validates the effectiveness of the modeling and simulations.

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Non-Similar Heat Transfer Characteristics Associated with Nanofluid Forced Convection Cooling and Heating

Proceedings of the 15th International Heat Transfer Conference ◽

10.1615/ihtc15.hte.008562 ◽

2014 ◽

Author(s):

Wenhao Li ◽

Akira Nakayama

Keyword(s):

Heat Transfer ◽

Forced Convection ◽

Heat Transfer Characteristics ◽

Transfer Characteristics ◽

Convection Cooling

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A Study of Forced Convection Direct Air Cooling in the Downstream Vicinity of Heat Sinks

Journal of Electronic Packaging ◽

10.1115/1.2904372 ◽

1990 ◽

Vol 112 (3) ◽

pp. 234-240 ◽

Cited By ~ 5

Author(s):

G. L. Lehmann ◽

S. J. Kosteva

Keyword(s):

Heat Transfer ◽

Forced Convection ◽

Heat Sink ◽

Convection Heat Transfer ◽

Heat Sinks ◽

Air Cooling ◽

Transfer Coefficients ◽

Packaging System ◽

Transfer Rates ◽

Heat Transfer Coefficients

An experimental study of forced convection heat transfer is reported. Direct air cooling of an electronics packaging system is modeled by a channel flow, with an array of uniformly sized and spaced elements attached to one channel wall. The presence of a single or complete row of longitudinally finned heat sinks creates a modified flow pattern. Convective heat transfer rates at downstream positions are measured and compared to that of a plain array (no heat sinks). Heat transfer rates are described in terms of adiabatic heat transfer coefficients and thermal wake functions. Empirical correlations are presented for both variations in Reynolds number (5000 < Re < 20,000) and heat sink geometry. It is found that the presence of a heat sink can both enhance and degrade the heat transfer coefficient at downstream locations, depending on the relative position.

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A Numerical and Experimental Study of a Novel Heat Sink Design for Natural Convection Cooling of LED Grow Lights

Energies ◽

10.3390/en13164046 ◽

2020 ◽

Vol 13 (16) ◽

pp. 4046

Author(s):

Ram Adhikari ◽

Dawood Beyragh ◽

Majid Pahlevani ◽

David Wood

Keyword(s):

Heat Transfer ◽

Natural Convection ◽

Heat Sink ◽

Large Scale ◽

High Efficiency ◽

Experimental Testing ◽

Growth Stages ◽

Air Cooling ◽

Convection Cooling ◽

Heat Sink Design

Light-emitting diode (LED) grow lights are increasingly used in large-scale indoor farming to provide controlled light intensity and spectrum to maximize photosynthesis at various growth stages of plants. As well as converting electricity into light, the LED chips generate heat, so the boards must be properly cooled to maintain the high efficiency and reliability of the LED chips. Currently, LED grow lights are cooled by forced convection air cooling, the fans of which are often the points of failure and also consumers of a significant amount of power. Natural convection cooling is promising as it does not require any moving parts, but one major design challenge is to improve its relatively low heat transfer rate. This paper presents a novel heat sink design for natural convection cooling of LED grow lights. The new design consists of a large rectangular fin array with openings in the base transverse to the fins to increase air flow, and hence the heat transfer. Numerical simulations and experimental testing of a prototype LED grow light with the new heat sink showed that openings achieved their intended purpose. It was found that the new heat sink can transfer the necessary heat flux within the safe operating temperature range of LED chips, which is adequate for cooling LED grow lights.

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New Bio-Inspired, Multiphase Forced Convection Cooling by ABS Plastic or Encapsulated Paraffin Beads

Journal of Heat Transfer ◽

10.1115/1.4000710 ◽

2010 ◽

Vol 132 (7) ◽

Cited By ~ 3

Author(s):

Fatemeh Hassanipour ◽

José L. Lage

Keyword(s):

Heat Transfer ◽

Forced Convection ◽

Particle Concentration ◽

Acrylonitrile Butadiene Styrene ◽

Parallel Plates ◽

Mixing Effect ◽

Particle Mixing ◽

Channel Temperature ◽

Convection Cooling ◽

Change Material

Preliminary experimental results of forced convection by octadecane paraffin (encapsulating phase-change material (EPCM)) particles, acrylonitrile butadiene styrene plastic particles, or by clear (of particulates) water flowing through a heated parallel-plates channel are reported. The objective is to investigate the mixing effect of the particles vis-à-vis the latent heat effect. The particle concentration is kept at 3% in volume. The results, in terms of surface-averaged channel temperature and heat transfer coefficient for different fluid speed and heat-flux, indicate the mixing effect to account from 19% to 68% of the heat transfer enhancement produced by using EPCM particles. Hence particle mixing, even at a very low particle concentration, is an effective convection mechanism.

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Enhancement of Forced Convection Subcooled Film Boiling Heat Transfer Using Gas Sheet Collapse by Electric Field Application

International Journal of Air-Conditioning and Refrigeration ◽

10.1142/s2010132518500116 ◽

2018 ◽

Vol 26 (02) ◽

pp. 1850011

Author(s):

Mitsuhiro Uemura

Keyword(s):

Heat Transfer ◽

Electric Field ◽

Cooling Rate ◽

Forced Convection ◽

Boiling Heat Transfer ◽

Pure Water ◽

Field Application ◽

Wire Surface ◽

Cooling Period ◽

Cooling Method

Enhancement of forced-convection boiling heat transfer by electric field is investigated experimentally. When a high-temperature horizontal filament is immersed in water, a gas sheet is formed around and the above filament due to liquid boiling, in the early immersion process. This gas-sheet markedly decreases the boiling cooling rate of the filament. Here, forced collapse of the gas sheet is attempted by imposing an electric field to enhance the boiling cooling rate, In the experiments, a horizontal platinum wire of 0.5[Formula: see text]mm in diameter is immersed in pure water under atmospheric pressure, and a DC voltage up to 600[Formula: see text]V is applied between the wire surface and an electrode made of glass placed 10[Formula: see text]mm apart. The whole boiling curve is measured under different applied voltages and wire-falling velocities in 0.5 to 2.0[Formula: see text]m/s range, and at subcooling of 60[Formula: see text]K. The experimental results show that the electric field is effective in promoting the disintegration of the gas sheet. Under the tested conditions, boiling cooling rate increased two-fold for an applied electric field of 600[Formula: see text]V/cm. This result shows that the use of an electric field to break up the gas-sheet has resulted in a remarkable increase in the cooling rate at high superheats during initial cooling period, which is even greater than that used in the existing material manufacturing processes by the rapid cooling method, and therefore, this method may contribute to developing new materials.

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