scholarly journals A study of jet impingement cooling enhancement by concave and convex heat sink shape modifications

2021 ◽  
Vol 323 ◽  
pp. 00010
Author(s):  
Marcin Froissart ◽  
Paweł Ziółkowski ◽  
Janusz Badur
Keyword(s):  
Nusselt Number ◽  
Heat Sink ◽  
Cold Water ◽  
Interaction Model ◽  
Jet Impingement ◽  
Shape Modification ◽  
Stagnation Region ◽  
Cooling Effectiveness ◽  
Impingement Cooling ◽  
Cooling Enhancement

The rising demand for efficient cooling technologies is a strong driver of extensive research in this area. This trend is particularly strong in turbines and microprocessors technology. Presented study is focused on the jet impingement cooling concept, which is used in various configurations for many years. The potential of the heat sink shape modification is not yet fully explored. Available literature suggests that average Nusselt number can be improved by more than 10% by adding conical shape in the stagnation region. This refers to the axisymmetric case where cold-water jet impinges the surface of heated aluminium. Presented results are based on 2D axisymmetric thermal-FSI (Fluid-Solid Interaction) model, which was validated against the experiment. The objective of the presented analysis is to determine the correlation between cooling effectiveness (Nusselt number) and chosen examples of concave and convex shapes located in the jet stagnation area.

Jet Impingement Cooling System on the Pressure Side of Turbine Blade

2014 ◽  
Vol 695 ◽  
pp. 503-507
Author(s):  
Mohamad Nor Musa ◽  
Mohamed Izhar Mohamed Khalid
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Turbine Blade ◽  
Nozzle Exit ◽  
Cooling System ◽  
Jet Impingement ◽  
Pressure Side ◽  
Cooling Effectiveness ◽  
Impingement Cooling ◽  
Surface Distance

This study is to investigate the effectiveness of jet impingement cooling system on the turbine blade pressure side. The objective of this study is to determine the mass blowing rate referred to Reynolds number and the nozzle exit to surface distance which will produce the highest cooling effectiveness which will be shown as Nusselt number. A model of CF6-50 blade is made from mild steel and an experiment to study the jet impingement cooling effectiveness on the pressure side of turbine blade is conducted. The parameters that are included in the experiment are the Reynolds number, Re = 646, 1322, 1970 and 2637; and nozzle exit to surface distance, s/d = 4.0 cm, 8.0 cm and 12.0 cm. The results obtained are calculated and graphs for each experiment are made. The result shows that the jet impingement cooling effectiveness are the highest at where the nozzle is pointed and the cooling effectiveness decreases as it travels further away on the blade. The theory of jet impingement cooling is presented and the several factors that affect jet impingement cooling are also discussed.

Experimental Investigation on Convective Heat Transfer Enhancement of Laminar Slot Jet Impingement in the Presence of Porous Medium

2016 ◽  
Author(s):  
Sampath Kumar Chinige ◽  
Arvind Pattamatta
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Porous Medium ◽  
Porous Media ◽  
Nusselt Number ◽  
Heat Sink ◽  
Average Nusselt Number ◽  
Jet Impingement ◽  
Transfer Enhancement ◽  
Porous Obstacle

An experimental study using Liquid crystal thermography technique is conducted to study the convective heat transfer enhancement in jet impingement cooling in the presence of porous media. Aluminium porous sample of 10 PPI with permeability 2.48e−7 and porosity 0.95 is used in the present study. Results are presented for two different Reynolds number 400 and 700 with four different configurations of jet impingement (1) without porous foams (2) over porous heat sink (3) with porous obstacle case (4) through porous passage. Jet impingement with porous heat sink showed a deterioration in average Nusselt number by 10.5% and 18.1% for Reynolds number of 400 and 700 respectively when compared with jet impingement without porous heat sink configuration. The results show that for Reynolds number 400, jet impingement through porous passage augments average Nusselt number by 30.73% whereas obstacle configuration enhances the heat transfer by 25.6% over jet impingement without porous medium. Similarly for Reynolds number 700, the porous passage configuration shows average Nusselt number enhancement by 71.09% and porous obstacle by 33.4 % over jet impingement in the absence of porous media respectively.

Effects of Nanoparticle Shape on Slot-Jet Impingement Cooling of a Corrugated Surface With Nanofluids

2017 ◽  
Vol 9 (2) ◽  
Author(s):  
Fatih Selimefendigil ◽  
Hakan F. Öztop
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Jet Impingement ◽  
Heat Transfer Characteristics ◽  
Impingement Cooling ◽  
Corrugated Surface ◽  
Nanoparticle Shapes

Numerical study of jet impingement cooling of a corrugated surface with water–SiO2 nanofluid of different nanoparticle shapes was performed. The bottom wall is corrugated and kept at constant surface temperature, while the jet emerges from a rectangular slot with cold uniform temperature. The finite volume method is utilized to solve the governing equations. The effects of Reynolds number (between 100 and 500), corrugation amplitude (between 0 and 0.3), corrugation frequency (between 0 and 20), nanoparticle volume fraction (between 0 and 0.04), and nanoparticle shapes (spherical, blade, brick, and cylindrical) on the fluid flow and heat transfer characteristics were studied. Stagnation point and average Nusselt number enhance with Reynolds number and solid particle volume fraction for both flat and corrugated surface configurations. An optimal value for the corrugation amplitude and frequency was found to maximize the average heat transfer at the highest value of Reynolds number. Among various nanoparticle shapes, cylindrical ones perform the best heat transfer characteristics in terms of stagnation and average Nusselt number values. At the highest solid volume concentration of the nanoparticles, heat transfer values are higher for a corrugated surface when compared to a flat surface case.

Effectiveness of Jet Impingement Cooling System on Convex Surface

2016 ◽  
Vol 819 ◽  
pp. 74-77
Author(s):  
Mohamad Nor Musa ◽  
Mohamad Faizal Fauzi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Transfer Coefficient ◽  
Convex Surface ◽  
Cooling System ◽  
Jet Impingement ◽  
Impingement Cooling ◽  
Reynolds Number Increase ◽  
Number Increase

Jet impingement is one of cooling method used in order to achieve high heat transfer coefficient and widely used in industry applications such as drying of textile and film, glass and plastic sheets, cooling of electronic equipment, and heat treatment of metals. In this research, it focused on the effectiveness of the jet impingement cooling system on the convex surface based on mass blowing rate and nozzle exit to surface parameters. The scope of experiment research encompasses are convex surface made of aluminum alloy and diameter 12.5cm. For mass blowing rate parameters, it use ʋjet = 1.98m/s, 3.03m/s, 4.97m/s and 6.00m/s which has Reynolds number range from 643 until 1946. Nozzle exit to surface distance,s/d = 4.0, 8.0 and 12.0. In this experiment model, a major components that involved are a compressor, nozzle, convex surface model, K thermocouple and heater. For the result of the experiment, it is based on the data obtain through a heat transfer coefficient and Nusselt number which the plotted graph focus on the space spacing and Reynolds number parameters. For the graph Nusselt number versus s/d at stagnation point c/d=0, it shown that when the Reynolds number increase, the Nusselt number also increase. In term of effectiveness, the s/d=12.0 has a good effectiveness jet impingement cooling system. For the graph of Nusselt number versus Reynolds at stagnation point, c/d=0, as Reynolds number increase, the Nusselt number increase too. From this experiment the better cooling effect is at Reynolds number, Re=1946. Thus, it can conclude that, effectiveness for jet impingement cooling system on the convex surface occurs at the highest Reynolds number.

Experimental and Numerical Study of Jet Impingement Cooling for Improved Gas Turbine Blade Internal Cooling With In-Line and Staggered Nozzle Arrays

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Abdel Rahman Salem ◽  
Farah Nazifa Nourin ◽  
Mohammed Abousabae ◽  
Ryoichi S. Amano
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Gas Turbine ◽  
Numerical Study ◽  
Turbine Blades ◽  
Jet Impingement ◽  
Target Surface ◽  
Internal Cooling ◽  
Impingement Cooling ◽  
Gas Turbine Blades

Abstract Internal cooling of gas turbine blades is performed with the combination of impingement cooling and serpentine channels. Besides gas turbine blades, the other turbine components such as turbine guide vanes, rotor disks, and combustor wall can be cooled using jet impingement cooling. This study is focused on jet impingement cooling, in order to optimize the coolant flow, and provide the maximum amount of cooling using the minimum amount of coolant. The study compares between different nozzle configurations (in-line and staggered), two different Reynold's numbers (1500 and 2000), and different stand-off distances (Z/D) both experimentally and numerically. The Z/D considered are 3, 5, and 8. In jet impingement cooling, the jet of fluid strikes perpendicular to the target surface to be cooled with high velocity to dissipate the heat. The target surface is heated up by a direct current (DC) power source. The experimental results are obtained by means of thermal image processing of the captured infra-red (IR) thermal images of the target surface. Computational fluid dynamics (CFD) analysis were employed to predict the complex heat transfer and flow phenomena, primarily the line-averaged and area-averaged Nusselt number and the cross-flow effects. In the current investigation, the flow is confined along with the nozzle plate and two parallel surfaces forming a bi-directional channel (bi-directional exit). The results show a comparison between heat transfer enhancement with in-line and staggered nozzle arrays. It is observed that the peaks of the line-averaged Nusselt number (Nu) become less as the stand-off distance (Z/D) increases. It is also observed that the fluctuations in the stagnation heat transfer are caused by the impingement of the primary vortices originating from the jet nozzle exit.

Experimental and Numerical Investigations on Jet Impingement Cooling for Electronic Modules

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Wen-Xiao Chu ◽  
Kuan-Chang Huang ◽  
Mohammed Amer ◽  
Chi-Chuan Wang
Keyword(s):  
Thermal Resistance ◽  
Flow Direction ◽  
Cross Flow ◽  
Jet Impingement ◽  
Stagnation Region ◽  
Impingement Cooling ◽  
Impingement Plate ◽  
Novel Design ◽  
Peak Value ◽  
Impingement Velocity

AbstractIn this paper, the influence of outlet arrangement and plenum structure on impingement cooling is experimentally and numerically investigated in a typical 1-U confined server space. Three outlets include Z-type, bilateral, and U-type arrangements, and the plenum configurations contain partially inclined, fully inclined, and staged layouts. As a result, using the U-type outlet or staged plenum may prominently compromise the impingement cooling performance on the target plates with lower pumping power. With numerical investigation, it is found that, for the case with Z-type outlet, the flowrate of jet impingement increases alongside the streamwise direction. Besides, the impingement stagnation region on target plates with the minimum thermal resistance may shift toward the outlet. Meanwhile, the uniformity of jet impingement can be improved by 10.7% and 50.3% when the bilateral and U-type outlets are applied, respectively, and the jet impingement is changed to perpendicular direction due to the opposite cross flow from the coming flow direction. On the other hand, by applying the inclined plenum and staged plenum, the uniformity of jet impingement can be dramatically improved by 113.9% and 215.1%, respectively. However, the local jet impingement velocity distribution is still nonuniform. Hence, a novel design of impingement plate based on the concept of Coanda effect is proposed. The peak value of the thermal resistance on target plate can be reduced by 21.8% and 16.0% at the center region and the fore part of the jet array.

High-Fidelity Simulations of Multi-Jet Impingement Cooling Flows

2020 ◽  
Author(s):  
J. Javier Otero-Pérez ◽  
Richard D. Sandberg ◽  
Satoshi Mizukami ◽  
Koichi Tanimoto
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Cross Flow ◽  
Distance Effect ◽  
Jet Impingement ◽  
Impingement Cooling ◽  
Cooling Flows ◽  
Turbulent Inflow ◽  
The Cross ◽  
Flow Effects

Abstract This article shows the first parametric study on turbulent multi-jet impingement cooling flows using large-eddy simulations (LES). We focus on assessing the influence of the inter-jet distance and the cross-flow conditions on the heat transfer at the impingement wall. The LES setup is thoroughly validated with both experimental and direct numerical simulation data, showing an excellent agreement. The inter-jet distance effect on the heat transfer is studied comparing three different distances, where the full Nusselt number profile decreases in amplitude when the jet distance is increased. To evaluate the cross-flow effects, we prescribe both laminar and turbulent inflow conditions at different cross-flow magnitudes ranging between 20% and 40% of the impinging jet speed. Large cross-flow intensities cause a jet deflection which reduces the maxima in the Nusselt number distribution, and it increases the heat transfer in the areas of the wall less affected by the jet impingement. Adding realistic turbulent fluctuations to the inflow enhances the cross-flow effects on the heat transfer at the impingement wall.

Thermal Performance of Mini-Scale Heat Sink With Jet Impingement and Roughened Surface

2016 ◽  
Author(s):  
Zhongyang Shen ◽  
Qi Jing ◽  
Yonghui Xie ◽  
Di Zhang
Keyword(s):  
Heat Transfer ◽  
Thermal Performance ◽  
Heat Sink ◽  
Jet Impingement ◽  
Feature Size ◽  
Impingement Cooling ◽  
Heat Transfer Augmentation ◽  
Roughened Surface ◽  
And Performance ◽  
Set Up

Cooling technique in mini-scale heat sink is essential with the development of high power electronics such as electronic chip. As heat transfer techniques, jet impingement cooling and convective cooling by roughened surface are commonly adopted. To obtain good cooling efficiency, the cooling structure within the heat sink should be carefully designed. In the present study, mini-scale heat sink with feature size of 1∼10 mm is set up. Arrangement of jet impingement and dimple/protrusion surface are designed as heat transfer augmentation approaches. The effect of dimple/protrusion configuration is discussed. From the result, the Nu distribution of on heat sink surface is demonstrated for each case. The pressure penalty due to the arrangement of roughened structure is evaluated. Also, thermal performance TP and performance evaluation plot are adopted as evaluations of cooling performance for each configuration. Comparing all cases, optimal cooling structure considering the energy saving performance is obtained for the mini-scale heat sink. Referencing the statistics, new insight has been provided for the design of cooling structure inside mini-scale heat sink.

Effects of Extended Jet Holes to Heat Transfer and Flow Characteristics of the Jet Impingement Cooling

2019 ◽  
Vol 141 (8) ◽  
Author(s):  
Ahmet Ümit Tepe ◽  
Kamil Arslan ◽  
Yaşar Yetişken ◽  
Ünal Uysal
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Average Nusselt Number ◽  
Flat Surface ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Jet Impingement ◽  
Target Surface ◽  
Impingement Cooling ◽  
Compressor Power

In this study, effects of extended jet holes to heat transfer and flow characteristics of jet impingement cooling were numerically investigated. Cross-flow in the impinging jet cooling adversely affects the heat transfer on the target surface. The main purpose of this study is to reduce the negative effect of cross-flow on heat transfer by extending jet holes toward the target surface with nozzles. This study has been conducted under turbulent flow condition (15,000 ≤ Re  ≤  45,000). The surface of the turbine blade, which is the target surface, has been modeled as a flat plate. The effect of the ribs, placed on the target surface, on the heat transfer has been also investigated, and the results were compared with the flat surface. The parameters such as average and local Nusselt numbers on the target surface, flow characteristics, and compressor power have been examined in detail. It was obtained from the numerical results that the average Nusselt number increases with decreasing the gap between the target surface and the nozzle. In addition, the higher average Nusselt number was obtained on the flat surface than the ribbed surface. The lowest compressor power was achieved in the 5Dj nozzle gap for the flat surface and in the 4Dj nozzle gap for the ribbed surface.

Thermal Characterization of Multiple Micro-Jet Impingement Cooling Model

2014 ◽  
Author(s):  
Afzal Husain ◽  
Jun-Hee Kim ◽  
Kwang-Yong Kim
Keyword(s):  
Laminar Flow ◽  
Heat Sink ◽  
Jet Impingement ◽  
Low Flow ◽  
Design Parameters ◽  
Computational Domain ◽  
Flow Conditions ◽  
Excessive Pressure ◽  
Impingement Cooling ◽  
Laminar Flow Conditions

The present study investigated thermal performance of silicon-based multiple micro-jet impingement cooling heat sink for thermal management of electronics. Three-dimensional numerical analysis was performed for steady incompressible laminar flow and conjugate heat transfer through a finite volume solver. A heat flux of 100 W/cm2 was applied at one side of the silicon substrate, while at the other side jet impingement system was designed. The jet plate was consisted of many jet holes whereas computational domain was simplified by utilizing symmetric boundary conditions along the flow as well as lateral directions. The effect of various design parameters, namely, jet diameter, jet pitch, standoff (distance from jet exit to impingement surface) etc., have been analyzed at jet Reynolds numbers 100, 200 and 300 under laminar flow conditions. In view of the low pumping powers available through micro-pumping systems, low flow rates were applied for the analysis. The cross-flow effects of the spent-flow were investigated for finding out optimum design parameters and flow conditions for the heat sink. The temperature distribution was discussed for various values of jet diameter, standoff and jet-to-jet spacing. While a moderate thermal resistance of the heat sink was obtained under laminar flow conditions, high performance can be achieved for higher flow-rate turbulent flow conditions at the expense of excessive pressure-drop which would be investigated in future studies.

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