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Near-field radiative heat transfer between nanoporous GaN films
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作者 韩晓政 张纪红 +2 位作者 刘皓佗 吴小虎 冷惠文 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第4期109-120,共12页
Photon tunneling effects give rise to surface waves,amplifying radiative heat transfer in the near-field regime.Recent research has highlighted that the introduction of nanopores into materials creates additional path... Photon tunneling effects give rise to surface waves,amplifying radiative heat transfer in the near-field regime.Recent research has highlighted that the introduction of nanopores into materials creates additional pathways for heat transfer,leading to a substantial enhancement of near-field radiative heat transfer(NFRHT).Being a direct bandgap semiconductor,GaN has high thermal conductivity and stable resistance at high temperatures,and holds significant potential for applications in optoelectronic devices.Indeed,study of NFRHT between nanoporous GaN films is currently lacking,hence the physical mechanism for adding nanopores to GaN films remains to be discussed in the field of NFRHT.In this work,we delve into the NFRHT of GaN nanoporous films in terms of gap distance,GaN film thickness and the vacuum filling ratio.The results demonstrate a 27.2%increase in heat flux for a 10 nm gap when the nanoporous filling ratio is 0.5.Moreover,the spectral heat flux exhibits redshift with increase in the vacuum filling ratio.To be more precise,the peak of spectral heat flux moves fromω=1.31×10^(14)rad·s^(-1)toω=1.23×10^(14)rad·s^(-1)when the vacuum filling ratio changes from f=0.1 to f=0.5;this can be attributed to the excitation of surface phonon polaritons.The introduction of graphene into these configurations can highly enhance the NFRHT,and the spectral heat flux exhibits a blueshift with increase in the vacuum filling ratio,which can be explained by the excitation of surface plasmon polaritons.These findings offer theoretical insights that can guide the extensive utilization of porous structures in thermal control,management and thermal modulation. 展开更多
关键词 near-field radiative heat transfer nanoporous GaN film surface phonon polaritons surface plasmon polaritons
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Numerical study of flow and thermal characteristics of pulsed impinging jet on a dimpled surface
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作者 Amin Bagheri Kazem Esmailpour Morteza Heydari 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2024年第2期106-117,共12页
This research comprehensively investigates the flow and thermal characteristics of a pulsating impinging jet over a dimpled surface.It analyzes the impact of key parameters(e.g.,inlet velocity pulsation functions,puls... This research comprehensively investigates the flow and thermal characteristics of a pulsating impinging jet over a dimpled surface.It analyzes the impact of key parameters(e.g.,inlet velocity pulsation functions,pulsation frequency,amplitude,dimple pitch,dimple depth,Reynolds number)on flow patterns and heat transfer.Validated computational fluid dynamics and the Re-normalization group turbulence model are employed to accurately simulate complex turbulent flow behavior.Local and average heat transfer coefficients are calculated and compared to steady impingement cases,revealing the potential benefits of pulsation for heat transfer enhancement.The study also examines how pulsation-induced flow modulation and thermal mixing affect heat transfer mechanisms.Results indicate that combining fluctuating flow with a dimpled surface can improve heat transfer rates.In summary,increasing pulsation amplitude consistently enhances heat transfer,while the effect of frequency varies between impinging and wall jet zones. 展开更多
关键词 Pulsating impinging jet Dimpled surface heat transfer enhancement Pulsation frequency and amplitude Coherent structures
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Heat Transfer Characteristics of Boiler Convective Heating Surface Under Pressurized Oxygen-fuel Combustion Conditions 被引量:8
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作者 Gao Zhengyang Xia Ruiqing Yan Weiping Ma Kai Feng Wenhui Zhang Bowen 《中国电机工程学报》 EI CSCD 北大核心 2012年第23期I0001-I0020,142,共20页
增压富氧燃烧是一项极具前景的减排CO2新技术。对增压富氧燃烧条件下,对流受热面换热特性进行研究具有重要的意义。该文以一台实际300MW等级机组煤粉锅炉为计算对象,采用维里方程及Chun等的计算方法计算确定增压富氧燃烧烟气物性,采用... 增压富氧燃烧是一项极具前景的减排CO2新技术。对增压富氧燃烧条件下,对流受热面换热特性进行研究具有重要的意义。该文以一台实际300MW等级机组煤粉锅炉为计算对象,采用维里方程及Chun等的计算方法计算确定增压富氧燃烧烟气物性,采用宽带关联k模型计算富氧燃烧烟气辐射特性。进行了常规空气燃烧以及φ(O2):φ(CO2)=21:79、φ(O2):φ(CO2)=30:70两种比例的0.1、0.5、1.0、1.5、6 MPa五种压力下增压富氧燃烧各对流受热面的热力计算,分析了增压富氧燃烧条件烟气压力变化对各受热面换热特性的影响。研究结果表明:随烟气压力的升高,烟气流速下降,但烟气的Re却基本保持不变,对流换热系数有所增加。增压富氧燃烧烟气的辐射换热系数比空气燃烧烟气辐射换热系数大。实现同样的换热量,增压富氧燃烧条件下(φ(O2):φ(CO2)=21:79、φ(O2):φ(CO2)=30:70)对流受热面所需换热面积比常规空气燃烧条件下少。 展开更多
关键词 对流受热面 燃料燃烧 传热特性 高压氧 燃烧条件 锅炉 排放控制技术 C02
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Concerning The Effect of Surface Material on Nucleate Boiling Heat Transfer of R-113 被引量:2
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作者 Reza Hosseini Amir Gholaminejad Mahdi Nabil 《Journal of Electronics Cooling and Thermal Control》 2011年第2期22-27,共6页
This paper presents results of an experimental investigation carried out to determine the effects of surface material on nucleate pool boiling heat transfer of refrigerant R113. Experiments were performed on horizonta... This paper presents results of an experimental investigation carried out to determine the effects of surface material on nucleate pool boiling heat transfer of refrigerant R113. Experiments were performed on horizontal circular plates of brass, copper and aluminum. The heat transfer coefficient was evaluated by measuring wall superheat and effective heat flux removed by boiling. The experiments were carried out in the heat flux range of 8 to 200 kW/m2. The obtained results have shown significant effect of surface material, with copper providing the highest heat transfer coefficient among the samples, and aluminum the least. There was negligible difference at low heat fluxes, but copper showed 23% better performance at high heat fluxes than aluminum and 18% better than brass. 展开更多
关键词 BOILING heat transfer R-113 Nucleate BOILING surface MATERIAL
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Pool boiling heat transfer enhancement on porous surface tube 被引量:2
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作者 LI Yong YAN Changqi SUN Zhongning SUN Licheng 《Nuclear Science and Techniques》 SCIE CAS CSCD 2011年第2期122-128,共7页
The passive residual heat removal exchanger (PRHR HX),which is a key equipment of the passive residual heat removal system,is installed in an elevated pool.Its heat transfer performance affects security and economics ... The passive residual heat removal exchanger (PRHR HX),which is a key equipment of the passive residual heat removal system,is installed in an elevated pool.Its heat transfer performance affects security and economics of the reactor,and boiling heat transfer in the liquid surrounding the exchanger occurs when the liquid saturation temperature exceeded.The smooth tubes,which are widely used as heat transfer tubes in PRHR HX,can be replaced by some enhanced tubes to improve the boiling heat transfer capability.In this paper,the pool boiling heat transfer characteristics of smooth tube and a machined porous surface tube are investigated by using high-pressure steam condensing inside tube as heating source.Compared with smooth tube,the porous surface tube considerably enhances the boiling heat transfer,and shortens the time significantly before reaching the liquid saturation temperature.Its boiling heat transfer coefficient increases from 68% to 75%,and the wall superheat decreases by 1.5oC.Combining effect of condensation inside tube with boiling outside tube,the axial wall temperatures of heat transfer tube are neither uniform nor linear distribution.Based on these investigations,enhance mechanism of the porous surface tube is analyzed. 展开更多
关键词 池沸腾传热 表面多孔管 强化传热 余热排出系统 多孔表面管 饱和液体 沸腾传热系数 温度超标
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Heat Transfer in a Liquid-Solid Circulating Fluidized Bed Reactor with Low Surface Tension Media 被引量:2
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作者 H.R.Jin H.Lim +2 位作者 D.H.Lim Y.Kang Ki-Won Jun 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2013年第8期844-849,共6页
Heat transfer characteristics between the immersed heater and the bed content were studied in the riser of a liquid-solid circulating fluidized bed, whose diameter and height were 0.102 m (ID) and 2.5 m, respectively.... Heat transfer characteristics between the immersed heater and the bed content were studied in the riser of a liquid-solid circulating fluidized bed, whose diameter and height were 0.102 m (ID) and 2.5 m, respectively. Effects of liquid velocity, particle size, surface tension of liquid phase and solid circulation rate on the overall heat transfer coefficient were examined. The heat transfer coefficient increased with increasing particle size or solid circulation rate due to the higher potential of particles to contact with the heater surface and promote turbulence near the heater surface. The value of heat transfer coefficient increased gradually with increase in the surface tension of liquid phase, due to the slight increase of solid holdup. The heat transfer coefficient increased with the liquid velocity even in the higher range, due to the solid circulation prevented the decrease in solid holdup, in contrast to that in the conventional liquid-solid fluidized beds. The values of heat transfer coefficient were well correlated in terms of dimensionless groups as well as operating variables. 展开更多
关键词 液固循环流化床 表面张力 传热特性 固体循环速率 总传热系数 媒体 加热器 表面接触
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Heat Transfer of Boiling R134a and R142b on a Twisted Tube with Machine Processed Porous Surface 被引量:1
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作者 高学农 尹辉斌 +3 位作者 黄玉优 凌双梅 张正国 方玉堂 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2008年第3期492-496,共5页
这个工作的目的是调查起核心作用有机器的一个扭曲的试管上的 R134a 和 R142b 的水池沸腾传热性能和机制处理了多孔的表面(T-MPPS 试管) 象一样决定它的潜在的申请到充满的致冷的蒸发器。在试验性的范围,一个 T-MPPS 试管上的 R134a ... 这个工作的目的是调查起核心作用有机器的一个扭曲的试管上的 R134a 和 R142b 的水池沸腾传热性能和机制处理了多孔的表面(T-MPPS 试管) 象一样决定它的潜在的申请到充满的致冷的蒸发器。在试验性的范围,一个 T-MPPS 试管上的 R134a 的沸腾传热系数是光管上的 R134a 的比那些大的 1.8-2.0 时间。另外,发达试验性的关联证实以试验性的条件在一个 T-MPPS 试管上煮 R134a 和 R142b 的传热系数的预言是更加精确的。 展开更多
关键词 R134A R142B 表面多孔螺旋扁管 沸腾 传热
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An Experimental Study of Porous Surface Tubes for Enhancement of Binary Liquid Mixture Pool Boiling Heat Transfer
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作者 朱冬生 童子龙 谭盈科 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 1998年第4期77-82,共6页
Experiments have been conducted on the pool boiling of binary mixtures in JK tubeswith porous surface and ribbed channels,attempting to enhace the boiling heat transfer coefficientsinvolved.The binary mixtures used in... Experiments have been conducted on the pool boiling of binary mixtures in JK tubeswith porous surface and ribbed channels,attempting to enhace the boiling heat transfer coefficientsinvolved.The binary mixtures used in this study are R113 and R11.The results show that the boilingfi1m heat transfer coefficients for the R113 and R11 binary mixtures in JK2 and JK1 tubes are 2—8tirnes and 2—5 times greater than those in smooth tubes respectively.Based on this experimentaldata and simple theoretical analysis,a correlation has been proposed to predict the boiling heattransfer coefficients for R113/R11 mixtures in a horizontal JK tube with a relative error of less than16%. 展开更多
关键词 POROUS surface tube POOL BOILING heat transfer ENHANCEMENT BINARY MIXTURE
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Heat transfer of liquid metal alloy on copper plate deposited with film of different surface free energy
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作者 闫慧龙 闫金良 赵刚 《Chinese Physics B》 SCIE EI CAS CSCD 2019年第11期217-221,共5页
Liquid metal alloys(LMAs) are the potential candidates of thermal interface materials(TIMs) for electronics cooling.In the present work, buffer layers of Ag, Ti, Cu, Ni, Mo, and W were deposited on polished Cu plates ... Liquid metal alloys(LMAs) are the potential candidates of thermal interface materials(TIMs) for electronics cooling.In the present work, buffer layers of Ag, Ti, Cu, Ni, Mo, and W were deposited on polished Cu plates by DC magnetron sputtering, the contact angles of de-ionized water and diiodomethane on the buffer layers were measured by an easy drop shape analyzer and the surface free energies(SFEs) of the buffer layers were calculated by the Owens–Wendt–Kaelble equation. Samples were prepared by sandwiching the filmed Cu plates and LMAs. The thermal properties of the samples were measured by laser flash analysis method. The SFE of the buffer layer has a strong influence on the interface heat transfer, whereas the measurement temperature has no obvious effect on the thermal properties of the samples. As the SFE of the buffer layer increases, the wettability, thermal diffusivity, and thermal conductivity are enhanced, and the thermal contact resistance is decreased. 展开更多
关键词 BUFFER layer LIQUID metal alloy thermal CONTACT resistance heat transfer surface free energy
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Exact solutions for the flow of Casson fluid over a stretching surface with transpiration and heat transfer effects
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作者 Swati Mukhopadhyay Krishnendu Bhattacharyya Tasawar Hayat 《Chinese Physics B》 SCIE EI CAS CSCD 2013年第11期356-361,共6页
The effects of transpiration on forced convection boundary layer non-Newtonian fluid flow and heat transfer toward a linearly stretching surface are reported. The flow is caused solely by the stretching of the sheet i... The effects of transpiration on forced convection boundary layer non-Newtonian fluid flow and heat transfer toward a linearly stretching surface are reported. The flow is caused solely by the stretching of the sheet in its own plane with a velocity varying linearly with the distance from a fixed point. The constitutive relationship for the Casson fluid is used. The governing partial differential equations corresponding to the momentum and energy equations are converted into non-linear ordinary differential equations by using similarity transformations. Exact solutions of the resulting ordinary differential equations are obtained. The effect of increasing Casson parameter, i.e., with decreasing yield stress (the fluid behaves as a Newtonian fluid as the Casson parameter becomes large), is to suppress the velocity field. However, the temperature is enhanced as the Casson parameter increases. It is observed that the effect of transpiration is to decrease the fluid velocity as well as the temperature. The skin-friction coefficient is found to increase as the transpiration parameter increases. 展开更多
关键词 stretching surface TRANSPIRATION Casson fluid heat transfer
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Unsteady heat and mass transfer in MHD flow over an oscillatory stretching surface with Soret and Dufour efects
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作者 Lian-Cun Zheng Xin Jin +1 位作者 Xin-Xin Zhang Jun-Hong Zhang 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2013年第5期667-675,共9页
In this paper, we study the unsteady coupled heat and mass transfer of two-dimensional MHD fluid over a moving oscillatory stretching surface with Soret and Dufour effects. Viscous dissipation effects are adopted in t... In this paper, we study the unsteady coupled heat and mass transfer of two-dimensional MHD fluid over a moving oscillatory stretching surface with Soret and Dufour effects. Viscous dissipation effects are adopted in the energy equation. A uniform magnetic field is applied vertically to the flow direction. The governing equations are reduced to non-linear coupled partial differential equations and solved by means of homotopy analysis method (HAM). The effects of some physical parameters such as magnetic parameter, Dufour number, Soret number, the Prandtl num- ber and the ratio of the oscillation frequency of the sheet to its stretching rate on the flow and heat transfer characteristics are illustrated and analyzed. 展开更多
关键词 Viscous conducted fluid Magnetic field Os- cillatory stretching surface heat and mass transfer HAM solution
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Application of Superhydrophobic Surface on Boiling Heat Transfer Characteristics of Nanofluids
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作者 Cong Qi Yuxing Wang +2 位作者 Zi Ding Jianglin Tu Mengxin Zhu 《Energy Engineering》 EI 2021年第4期825-852,共28页
Boiling heat transfer is a mode using the phase change of working medium to strengthen the heat exchange due to its good heat exchange capability,and it is widely used in heat exchange engineering.Nanofluids have been... Boiling heat transfer is a mode using the phase change of working medium to strengthen the heat exchange due to its good heat exchange capability,and it is widely used in heat exchange engineering.Nanofluids have been used in the direction of enhanced heat transfer for their superior thermophysical property.The wetting,spreading and ripple phenomena of superhydrophobic surfaces widely exist in nature and daily life.It has great application value for engineering technology.In this article,the boiling heat exchange characteristics of nanofluids on superhydrophobic surface are numerically studied.It was found that with the increase of superheating degree,the steam volume ratio of unmodified heated surface increases to saturation,while the steam volume and evaporation ratio of modified superhydrophobic surface increase firstly and then decrease.At the same time,bubbles are generated and accumulated more fully on superhydrophobic surface.It was also found that nanofluids with low viscosity are more affected by superhydrophobic surface characteristics,and the increase is more significant with high superheating degree,and the superhydrophobic surface is beneficial to enhancing boiling heat exchange.Compared with the simulation results,it could be concluded that the boiling heat exchange performance of CuO-water nano-fluids on the modified superhydrophobic surface is better than that of CuO-ethylene glycol nanofluids under high superheating degree. 展开更多
关键词 Nanofluids superhydrophobic surface pool boiling heat transfer numerical simulation
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Time Dependent Surface Heat Transfer in Light Weight Aggregate Cement Based Materials
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作者 Hung T. Nguyen Frank Melandso Stefan Jacobsen 《Engineering(科研)》 2010年第5期307-317,共11页
Surface temperature changes of building materials affect the calculation of heat flow and thus the energy use in heating and cooling. The surface heat transfer coefficient , limiting the heat flow between material sur... Surface temperature changes of building materials affect the calculation of heat flow and thus the energy use in heating and cooling. The surface heat transfer coefficient , limiting the heat flow between material surface and ambient air is normally taken as a constant. In this study we propose a time-dependent function . We estimate from unidirectional heat flow experiments with transient and steady-state conditions. Using temperature measurements and the conservation of energy at the surface including convective and irradiative boundary conditions, the value of was obtained both using Finite Difference and Taylor Polynomials methods. Numerical solutions of temperature distribution as function of time were improved with the obtained -functions compared to with constant . There were no clear difference between on different materials, and the final values observed were in the order of magnitude expected from the literature. 展开更多
关键词 heat Flow surface heat transfer Coefficient Numerical Methods Light WEIGHT AGGREGATE CEMENTS Based Materials
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MHD Stagnation Point Flow and Heat Transfer over a Permeable Surface
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作者 Santosh Chaudhary Pradeep Kumar 《Engineering(科研)》 2013年第1期50-55,共6页
The steady two-dimensional, laminar flow of a viscous, incompressible, electrically conducting fluid near a stagnation point with heat transfer over a permeable surface in the presence of a uniform magnetic field is c... The steady two-dimensional, laminar flow of a viscous, incompressible, electrically conducting fluid near a stagnation point with heat transfer over a permeable surface in the presence of a uniform magnetic field is considered. Taking suitable similarity variables, the governing boundary layer equations are transformed to ordinary differential equations and solved numerically by Shooting method. The effects of the suction parameter, the magnetic parameter, the Prandtl number and the Eckert number are studied on the velocity and temperature distributions. 展开更多
关键词 MHD STAGNATION POINT heat transfer PERMEABLE surface
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Numerical Modeling of Non-Similar Mixed Convection Heat Transfer over a Stretching Surface with Slip Conditions
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作者 A. Subba Rao V. R. Prasad +3 位作者 N. Nagendra K. V. N. Murthy N. Bhaskar Reddy O. Anwar Beg 《World Journal of Mechanics》 2015年第6期117-128,共12页
In this paper, the heat transfer effect on the steady boundary layer flow of a Casson fluid past a stretching surface in the presence of slip conditions was analyzed. The stretching surface is maintained at a constant... In this paper, the heat transfer effect on the steady boundary layer flow of a Casson fluid past a stretching surface in the presence of slip conditions was analyzed. The stretching surface is maintained at a constant temperature. The boundary layer conservation equations, which are parabolic in nature, are normalized into non-similar form and then solved numerically with the well-tested, efficient, implicit, stable Keller-box finite difference scheme. The resulting equations are solved numerically by using the Kellerbox finite-difference method, and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for non-Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that both velocity and temperature decrease with an increase of the Casson fluid parameter. 展开更多
关键词 STRETCHING surface Non-Newtonian Fluid SLIP Condition Keller-Box NUMERICAL Method heat transfer Skin Friction Coefficient
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IMPINGEMENTHEATTRANSFERFROMRIBROUGHENEDSURFACEWITHINARRAYSOFCIRCULARJET
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作者 Chang Haiping Zhang Dalin Han Dong Huang Taiping Department of Power Engineering, NUAA29 Yudao Street, Nanjing 210016, P. R. China 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1996年第1期64-70,共7页
实验研究了二维圆射流阵列冲击肋粗糙表面换热。所研究的具有初始横流对肋粗糙表面的冲击流动与换热特性,是为了模拟存在初始横流的涡轮叶片中弦区的冲击冷却。研究包括Rej=8000~11000,Z/d=1.5~3.0条件下的光滑表面与肋粗糙表... 实验研究了二维圆射流阵列冲击肋粗糙表面换热。所研究的具有初始横流对肋粗糙表面的冲击流动与换热特性,是为了模拟存在初始横流的涡轮叶片中弦区的冲击冷却。研究包括Rej=8000~11000,Z/d=1.5~3.0条件下的光滑表面与肋粗糙表面,横流率为Gc/Gj=0~0.55范围内。实验结果表明,初始横流率对肋粗糙表面的冲击换热有重要的影响。与光滑表面相比,圆射流阵列冲击肋粗糙表面的换热效率。 展开更多
关键词 换热 流动 冲击冷却 肋粗糙表面 初始横流
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Heat Generation Effects on MHD Natural Convection Flow along a Vertical Wavy Surface with Variable Thermal Conductivity 被引量:1
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作者 Md Abdul Alim Md Rezaul Karim Md Miraj Akand 《American Journal of Computational Mathematics》 2012年第1期42-50,共9页
The heat generation effects on magnetohydrodynamic(MHD) natural convection flow along a vertical wavy surface with variable thermal conductivity have been investigated. The governing boundary layer equations are first... The heat generation effects on magnetohydrodynamic(MHD) natural convection flow along a vertical wavy surface with variable thermal conductivity have been investigated. The governing boundary layer equations are first transformed into a non-dimensional form using suitable set of dimensionless variables. The resulting nonlinear system of partial differential equations are mapped into the domain of a vertical flat plate and then solved numerically employing the implicit finite difference method, known as Keller-box scheme. The numerical results of the surface shear stress in terms of skin friction coefficient and the rate of heat transfer in terms of local Nusselt number, the stream lines as well as the isotherms are shown graphically for a selection of parameters set consisting of thermal conductivity variation parameter, heat generation parameter Q, magnetic parameter M and Prandtl number Pr. Comparison of numerical results of present work with other published data has been shown in table. 展开更多
关键词 NATURAL CONVECTION MAGNETOHYDRODYNAMICS heat transfer Wavy surface Temperature Dependent Thermal CONDUCTIVITY heat Generation
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Enhancement of natural convection heat transfer from a fin by triangular perforation of bases parallel and toward its tip 被引量:3
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作者 Abdullah H.AlEssa Mohamad I.Al-Widyan 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2008年第8期1033-1044,共12页
This study examines the heat transfer enhancement from a horizontal rectangular fin embedded with triangular perforations (their bases parallel and toward the fin tip) under natural convection. The fin's heat dissi... This study examines the heat transfer enhancement from a horizontal rectangular fin embedded with triangular perforations (their bases parallel and toward the fin tip) under natural convection. The fin's heat dissipation rate is compared to that of an equivalent solid one. The parameters considered are geometrical dimensions and thermal properties of the fin and the perforations. The gain in the heat transfer enhancement and the fin weight reduction due to the perforations are considered. The study shows that the heat dissipation from the perforated fin for a certain range of triangular perforation dimensions and spaces between perforations result in improvement in the heat transfer over the equivalent solid fin. The heat transfer enhancement of the perforated fin increases as the fin thermal conductivity and its thickness are increased. 展开更多
关键词 finned surfaces heat transfer enhancement triangular perforations natural convection finite element perforated fin heat dissipation
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Effect of viscous dissipation and heat source on flow and heat transfer of dusty fluid over unsteady stretching sheet 被引量:2
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作者 B.J.GIREESHA G.S.ROOPA C.S.BAGEWADI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2012年第8期1001-1014,共14页
This paper investigates the problem of hydrodynamic boundary layer flow and heat transfer of a dusty fluid over an unsteady stretching surface. The study considers the effects of frictional heating (viscous dissipat... This paper investigates the problem of hydrodynamic boundary layer flow and heat transfer of a dusty fluid over an unsteady stretching surface. The study considers the effects of frictional heating (viscous dissipation) and internal heat generation or ab- sorption. The basic equations governing the flow and heat transfer are reduced to a set of non-linear ordinary differential equations by applying suitable similarity transformations. The transformed equations are numerically solved by the Runge-Kutta-Fehlberg-45 order method. An analysis is carried out for two different cases of heating processes, namely, variable wall temperature (VWT) and variable heat flux (VHF). The effects of various physical parameters such as the magnetic parameter, the fluid-particle interaction pa- rameter, the unsteady parameter, the Prandtl number, the Eckert number, the number density of dust particles, and the heat source/sink parameter on velocity and temperature profiles are shown in several plots. The effects of the wall temperature gradient function and the wall temperature function are tabulated and discussed. 展开更多
关键词 heat transfer boundary layer flow stretching surface dusty fluid viscousdissipation non-uniform heat source numerical solution
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Impinging Cooling with a Crescent Surface Inspired by Barchan Dunes in a Simplified Gas Turbine Transition Section 被引量:1
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作者 GUO Haotian XU Tao +3 位作者 LIANG Xiao YU Zhenglei XING Genyuan GUO Huan 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2019年第5期760-768,共9页
For the enhancement of heat transfer efficiency,a novel turbulator inspired by the morphology of barchan dunes,called the mimetic barchan dune(MBD)turbulator,is designed and evaluated in the simplified gas turbine tra... For the enhancement of heat transfer efficiency,a novel turbulator inspired by the morphology of barchan dunes,called the mimetic barchan dune(MBD)turbulator,is designed and evaluated in the simplified gas turbine transition section.By using computational fluid dynamics(CFD),the numerical simulations for comparison have been carried out,concluding the smooth thermal surface,a thermal surface with riblet-shaped turbulator and a thermal surface with MBD turbulator.Then,two indicators are investigated for evaluating the coolant performance which are the heat transfer efficiency(η)on the outlet and the pressure loss(ΔP)in the coolant chamber.The numerical results show that the coolant has the best heat transfer efficiency with less pressure loss in the coolant chamber with the MBD turbulator.Then,the effect of the MBD turbulator sizes on heat transfer efficiency is investigated.When the height of the MBD turbulator(h)is set at 8 mm,the maximum amount of heat that could be transfered by the coolant is up to566.2 K and the corresponding heat transfer efficiency is 26.62%.The detail flows have been shown to elucidate the function of the MBD surface which may greatly arouse more design for solving harsh circumstance. 展开更多
关键词 convective heat transfer gas turbine simplified transition piece model MIMETIC thermal surface BARCHAN DUNES computational fluid dynamics(CFD)
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