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CFD study of turbulent jet impingement on curved surface

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Chinese Journal of Chemical Engineering 2016年第5期24卷 588-596页

作者： Javad Taghinia Md Mizanur Rahman Timo Siikonen Aalto University School of EngineeringDepartment of Applied MechanicsFI-00076Finland Hong Kong University of Science and Technology Department of Civil and Environmental EngineeringClear Water BayHong KongChina

The heat transfer and flow characteristics of air jet impingement on a curved surface are investigated with computational fluid dynamics(CFD)*** first applied model is a one-equation SGS model for large eddy simulation(LES)and the second one is the SST-SAS hybrid *** models are utilized to study the flow physics in impinging process on a curved surface for different jet-to-surface(h/B)distances at two Reynolds numbers namely,2960 and 4740 based on the jet exit velocity(U_e)and the hydraulic diameter(2B).The predictions are compared with the experimental data in the literature and also the results from RANS k-ε*** show that both models can produce relatively good ***,one-equation model(OEM)produced more accurate results especially at impingement region at lower jet-to-surface *** terms of heat transfer,the OEM also predicted better at different jet-to-surface *** is also observed that both models show similar performance at higher h/B ratios.

关键词： jet impingement Curved surface RAST one-equation model Large eddy simulation Heat transfer

Combined effects of local curvature and elasticity of an isothermal wall for jet impingement cooling under magnetic field effects

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Journal of Central South University 2021年第11期28卷 3534-3544页

作者： SELİMEFENDİGİL Fatih ÇOĞAN Mehmet ÖZTOP Hakan F. Department of Mechanical Engineering Celal Bayar UniversityManisa 45140Turkey Department of Mechanical Engineering Technology FacultyFırat UniversityElazığ23119Turkey

The aim of this study is to examine the effects of local curvature and elastic wall effects of an isothermal hot wall for the purpose of jet impingement cooling *** element method was used with *** important parametric effects such as Re number(between 100 and 700),Ha number(between 0 and 20),elasticity(between 104 and 109),curvature of the surface(elliptic,radius ratio between 1 and 0.25) and nanoparticle volume fraction(between 0 and 0.05) on the cooling performance were investigated *** results showed that the average Nu number enhances for higher Hartmann number,higher values of elastic modulus of partly flexible wall and higher nanoparticle volume *** the magnetic field is imposed at the highest strength,there is an increase of3.85% in the average Nu for the curved elastic wall whereas it is 89.22% for the hot part above it,which is due to the vortex suppression *** inclusion in the base fluid improves the heat transfer rate by about 27.6% in the absence of magnetic field whereas it is 20.5% under the effects of magnetic field at Ha=*** effects become important for higher Re numbers and at Re=700,there is 14.11% variation in the average Nu between the cases with the lowest and highest radius *** elastic wall effects on the heat transfer are reduced with the increased curvature of the bottom wall.

关键词： jet impingement nanoparticles elastic wall MHD CFD curved wall

Experimental Study on jet impingement Boiling Heat Transfer in Brass Beads Packed Porous Layer

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Journal of Thermal Science 2020年第3期29卷 718-729页

作者： ZHANG Yunsong CHEN Wei Merchant Marine College Shanghai Maritime UniversityShanghai 201306China

jet impingement boiling has been widely used in industrial facilities as its higher heat transfer coefficient(HTC)and critical heat flux(CHF)can be achieved in comparison with the pool *** covering beads packed porous layer on the heated wall surface,the enlarged heat transfer area and rise of nucleation sites for boiling occur,thus,the heat transfer performance of boiling can be *** the jet impingement boiling with brass bead packed porous layers,the heat transfer performance is crucially influenced by the characteristics of porous layer and working fluid flow,so the experiments were conducted to investigate the effects of the jet flow rate,fluid inlet subcooling,number of porous layer and brass bead diameter of porous *** study shows that impingement boiling promotes the HTC and CHF as 1.5 times and 2.5 times respectively as pool boiling at similar *** heat transfer performance can be obtained in the cases of a higher jet flow rate and a higher fluid inlet subcooling,and there exist the optimal layer number and bead diameter for heat ***,a double-layer porous layer results in an increase of 39%in heat flux at superheat of 30 K compared with a single-layer case;a single porous layer at d=8 mm brings an increase of 23%in heat flux at superheat of 30 K compared with that of bare plain ***,the actual scene of jet impingement boiling was recorded with a camera to investigate the behavior evolution of vapor bubbles which is highly correlated to the heat transfer process.

关键词： jet impingement nucleate boiling beads packed porous layer heat transfer coefficient critical heat flux

Experimental study on heat transfer enhancement of square-array jet impingement by using an integrated synthetic jet actuator

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Science China(Technological Sciences) 2023年第12期66卷 3439-3449页

作者： TAN JunWen LYU YuanWei ZHANG JingZhou ZHANG JingYang College of Energy and Power Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Astronautics Nanjing University of Aeronautics and AstronauticsNanjing 210016China

A novel concept is proposed in the present study for improving the square-array jet impingement heat transfer by integrating a synthetic jet actuator into the array *** illustrate the potential of this concept,an experimental investigation is performed,wherein two jet Reynolds numbers(Re=3000 and 5000),three hole-to-hole pitches(X/d=Y/d=4,5 and 6),and three impinging distances(H/d=2,6 and 10)are considered while the synthetic jet is actuated at a fixed frequency of 180 Hz with a characteristic Reynolds number(Re_(0))of about *** results show that the synthetic jet has rare influence on the stagnation heat transfer of square-array jet but effectively improves the local heat transfer at the central zone of array *** potential is tightly dependent on the array layout,Reynolds number and impinging *** general,the spatially-averaged Nusselt number augment behaves more significantly for the situations with smaller jet Reynolds number and bigger impinging distance.

关键词： jet impingement heat transfer enhancement square-array jet synthetic jet actuator

Experimental Investigation on Flow and Heat Transfer of jet impingement inside a Semi-Confined Smooth Channel

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Transactions of Nanjing University of Aeronautics and Astronautics 2014年第1期31卷 16-25页

作者：张靖周刘波徐华胜 Jiangsu Province Key Laboratory of Aerospace Power System Nanjing University of Aeronautics and Astronautics College of Energy and Power Engineering Nanjing University of Aeronautics and Astronautics China Gas Turbine Establishment Aviation Industry Corporation of China

Experimental investigation is conducted to investigate the flow and heat transfer performances of jet impingement cooling inside a semi-confined smooth *** of jet Reynolds number(varied from 10 000to 45000),orifice-to-target spacing(zn=1d—4d)and jet-to-jet pitches(xn=3d—5d,yn=3d—5d)on the convective heat transfer coefficient and discharge coefficient are *** a single-row jets normal impingement,the impingement heat transfer is enhanced with the increase of impingement Reynolds number or the decrease of spanwise jet-to-jet *** highest local heat transfer is achieved when zn/dis *** the double-row jets normal impingement,the laterally-averaged Nusselt number distributions in the vicinity of the first row jets impinging stagnation do not fit well with the single-row *** highest local heat transfer is obtained when zn/dis 1.A smaller jetto-jet pitch generally results in a lower discharge *** discharge coefficient in the double-row case is decreased relative to the single-row case at the same impingement Reynolds number.

关键词： jet impingement semi-confined channel convective heat transfer discharge coefficient

Gaskinetic Solutions for High Knudsen Number Planar jet impingement Flows

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Communications in Computational Physics 2013年第9期14卷 960-978页

作者： Chunpei Cai Chun Zou Department of Mechanical and Aerospace Engineering New Mexico State UniversityLas CrucesNew Mexico88003USA

This paper presents a gaskinetic study and analytical results on high speed rarefied gas flows from a planar *** beginning of this paper reviews the results for planar free jet expanding into a vacuum,followed by an investigation of jet impingement on normally set plates with either a diffuse or a specular *** results include exact solutions for flowfield and surface *** simulations with the direct simulation Monte Carlomethod were performed to validate these analytical results,and good agreement with this is obtained for flows at high Knudsen *** highly rarefied jet and jet impingement results can provide references for real jet and jet impingement flows.

关键词： Gaskinetic theory jet jet impingement Monte Carlo method

Theoretical Analysis of Hydraulic Jump on ExtremelySmall Size Liquid jet impingement

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Journal of Thermal Science 1998年第3期7卷 176-180页

作者： Dingwei Zhou Chongfang Ma Yutao Ren School of Energy and Power Engineering Xi’an Jiaotong University Xi’an China Department of Thermal Science and Engineering Beijing Polytechnic University Beijing China Second Rolling Mill Taiyuan Iron & Steel Group Corporation Taiyuan China

A theoretical study was conducted to characterize hydraulic jump of laminar circular liquid jets. The objective of this research was to determine the jump location in a simple explicit form. The effects of many factors were investigated including nozzle diameter, jet exit pressure, nozzle-to-plate spacing, jet velocity and Reynolds number. It was found that the theoretical data collapsed well over the range of jet Reynolds number 500 Re 1800 with previous data.

关键词： hydraulic jump jet impingement theoretical analysis

Planar collisionless jet impingement on a specular reflective plate

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Theoretical & Applied Mechanics Letters 2012年第2期2卷 41-45页

作者： Chunpei Cai Chun Zou Department of Mechanical and Aerospace Engineering New Mexico State University Las CrucesNew Mexico 88003 USA

This paper presents a fundamental gas-kinetic study on a high speed planar rarefied jet impinging on a flat plate of specular reflections. Based on previous collisionless planar free jet results, it is straightforward to obtain jet impingement flowfield solutions, and jet impingement for specular reflective plate surface properties. Several direct simulation Monte Carlo simulation results are provided and they validate these analytical solutions of rarefied planar jet flows. The results can find applications in many disciplines, such as materials processing, molecular beams, and space engineering.

关键词： rarefied flows jet impingement vacuum Monte Carlo method

Modeling and Simulation of a Hybrid jet-impingement/Micro-Channel Heat Sink

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Fluid Dynamics & Materials Processing 2021年第1期17卷 109-121页

作者： Taidong Xu Hao Liu Dejun Zhang Yadong Li Xiaoming Zhou Research Institute of CSIC Nanjing211153China University of Electronic Science and Technology of China Chengdu611731China

With the progressive increase in the number of transistors that can be accommodated on a single integrated circuit,new strategies are needed to extract heat from these devices in an efficient *** this regard methods based on the combination of the so-called“jet impingement”and“micro-channel”approaches seem extremely promising for possible improvement and future applications in electronics as well as the aerospace and biomedical *** this paper,a hybrid heat sink based on these two technologies is analysed in the frame of an integrated *** CFD simulation of the coupled flow/temperature fields and orthogonal tests are performed in order to optimize the overall *** influence of different sets of structural parameters on the cooling performance is *** is shown that an optimal scheme exists for which favourable performance can be obtained in terms of hot spot temperature decrease and thermal uniformity improvement.

关键词： jet impingement micro-channel heat sink numerical simulation orthogonal test