Journal of Heat Transfer-transactions of The Asme最新文献_第4页

Heat Transfer and Pressure Loss Correlations for Leading Edge, Jet Impingement Using Racetrack-Shaped Jets With Filleted Edges 利用带圆角边的赛道型射流前缘撞击的传热和压力损失相关性

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Journal of Heat Transfer-transactions of The Asme Pub Date : 2023-08-11 DOI: 10.1115/1.4063152

Ritwik Kulkarni, L. Wright

{"title":"Heat Transfer and Pressure Loss Correlations for Leading Edge, Jet Impingement Using Racetrack-Shaped Jets With Filleted Edges","authors":"Ritwik Kulkarni, L. Wright","doi":"10.1115/1.4063152","DOIUrl":"https://doi.org/10.1115/1.4063152","url":null,"abstract":"\u0000 This paper presents an experimental investigation of heat transfer and pressure loss for leading edge jet impingement using racetrack shaped jets. The majority of literature for gas turbine cooling applications considers jet impingement using square, or sharp-edged orifices. However, the edge of the jet orifices generally has some degree of filleting (or rounding) along the edges, due to casting the airfoils or material wear due to long-term operation. Engineers need data under realistic engine configurations to improve the utilization of coolant while adequately protecting the airfoil. The current experimental study is a parametric investigation of heat transfer and pressure loss for leading edge jet impingement, where the effects of jet Reynolds number (Re = 10,000 - 100,000), jet - to - jet spacing (s/d = 2 - 8), jet - to - target surface spacing (z/d = 2 - 4), surface curvature (D/d = 2.67 - 5.33), and jet fillet - to - jet plate thickness (r/l = 0.16 - 0.5) are each considered. The edge rounding at both the inlet and outlet of the jet plate yields reduced heat transfer compared to the square edged jets. However, the fillets significantly improve the discharge coefficients associated with the racetrack shaped orifices. With the extensive testing completed in this study, design correlations have been developed to predict the surface Nusselt number and discharge coefficients, with 10% and 19% deviation from experimental results, respectively. Engine designers can predict the level of heat transfer and pressure loss for leading edge jet impingement using these correlations.","PeriodicalId":15937,"journal":{"name":"Journal of Heat Transfer-transactions of The Asme","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88991331","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Discussion On "three-dimensional Stagnation Point Flow and Heat Transfer of a Dusty Fluid Toward a Stretching Sheet, M. R. Mohaghegh, Asghar by Rahimi, Journal of Heat Transfer, 2016, 138, 112001? “三维滞止点流动与含尘流体向拉伸板的传热”，M. R. mohaghgh, Asghar, Rahimi，传热学报，2016,38 (11):2001?

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Journal of Heat Transfer-transactions of The Asme Pub Date : 2023-08-11 DOI: 10.1115/1.4063151

A. Pantokratoras

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Visual Observation and Analytical Study of the Heat Load Sharing Mode in Multi-Evaporator Loop Heat Pipe 多蒸发器环路热管热负荷分担方式的可视化观察与分析研究

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Journal of Heat Transfer-transactions of The Asme Pub Date : 2023-08-11 DOI: 10.1115/1.4063153

Masafumi Kizawa, N. Watanabe, A. Ueno, X. Chang, H. Nagano

{"title":"Visual Observation and Analytical Study of the Heat Load Sharing Mode in Multi-Evaporator Loop Heat Pipe","authors":"Masafumi Kizawa, N. Watanabe, A. Ueno, X. Chang, H. Nagano","doi":"10.1115/1.4063153","DOIUrl":"https://doi.org/10.1115/1.4063153","url":null,"abstract":"\u0000 In this paper, the operating characteristics of the heat load sharing mode of multiple-evaporator loop heat pipe (MLHP) were elucidated based on a visual observation test. The heat load sharing mode is a function of MLHPs that can share the heat between the evaporators through the vapor without electronic power for the heat storage utilization. A visualized MLHP with two evaporators and one condenser was designed and fabricated. To simulate the heat load sharing mode in the MLHP, one evaporator was heated in the range of 40-280 W and the other evaporator was cooled using a water jacket in the range of 10-80 °C. Under the heat load sharing mode, the flow behaviors in the evaporator cores and the compensation chambers (CCs) were visually observed using borescope cameras, respectively. Moreover, two operating modes (defined as Mode A and Mode B) that affect the maximum heat sharing capability were identified. In Mode A, the heat sharing rate was proportional to the heat dissipation at the cooled side of evaporator, where the capillary force at the wick significantly affect the operation mode. By contrast, in Mode B the heat sharing rate reached the upper limit and then was constant regardless of the heat dissipation. Furthermore, the proposed concept model can predict the transition of the operation mode from Mode A to Mode B.","PeriodicalId":15937,"journal":{"name":"Journal of Heat Transfer-transactions of The Asme","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73657659","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Analytical Fractal Model for Effective Thermal Conductivity of Open-Cell Metallic Foams with Coated Hollow Ligaments 包覆空心韧带开孔金属泡沫有效导热系数的解析分形模型

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Journal of Heat Transfer-transactions of The Asme Pub Date : 2023-08-11 DOI: 10.1115/1.4063149

Tian Xiao, Liu Lu, Chenlei Yu, S. Boetcher, Xiaohu Yang, Moxiao Li, T. Lu

{"title":"Analytical Fractal Model for Effective Thermal Conductivity of Open-Cell Metallic Foams with Coated Hollow Ligaments","authors":"Tian Xiao, Liu Lu, Chenlei Yu, S. Boetcher, Xiaohu Yang, Moxiao Li, T. Lu","doi":"10.1115/1.4063149","DOIUrl":"https://doi.org/10.1115/1.4063149","url":null,"abstract":"\u0000 Coating the hollow ligaments of open-cell (fluid-through) metallic foams (MFs) fabricated via the sintering route with a thin layer of graphene can improve the effective thermal conductivity (ETC) of the foam without significantly increasing its flow resistance, potentially important for thermal storage applications. However, the Euclidean geometry cannot accurately depict the random distribution of pores within MFs. To this end, the present study aims to analyze how such thin coatings affect the ETC of MF by employing the fractal theory to depict the random distribution of its open pores. Subsequently, a cubic representative structure (RS) is chosen for self-similar pores in the fractal to establish a correlation between the geometric parameters of MF and its fractal dimension. Upon determining the thermal resistance provided a RS of the foam having coated hollow ligaments, its ETC is derived as a function of fractal dimension, dimensionless parameters of pore size, porosity, and thermal conductivity of relevant materials (e.g., ligaments, coatings, and filling medium). For validation, existing experimental data are used to compare with analytical predictions, with good agreement achieved. It is demonstrated that the ligament hollowness weakens the thermal conduction of MFs. In addition, when the coating has a thermal conductivity greater than that of ligament, the coating enhances the ability of the foam to conduct heat. Although the ligament hollowness and coating thickness are imperative factors affecting the ETC, the material makes of ligament and coating plays a decisive role in the ETC.","PeriodicalId":15937,"journal":{"name":"Journal of Heat Transfer-transactions of The Asme","volume":"39 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84594944","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Combined Effect of Bubble Size and Gas Volume Fraction On Natural Convective Heat Transfer Enhancement in Homogeneous Bubbly Flow: Eulerian-Eulerian Numerical Simulations 气泡尺寸和气体体积分数对均匀气泡流动中自然对流换热增强的综合影响:欧拉-欧拉数值模拟

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Journal of Heat Transfer-transactions of The Asme Pub Date : 2023-08-11 DOI: 10.1115/1.4063150

D. Law, Arun Sriniwas Selvamani, Luis Nava

{"title":"Combined Effect of Bubble Size and Gas Volume Fraction On Natural Convective Heat Transfer Enhancement in Homogeneous Bubbly Flow: Eulerian-Eulerian Numerical Simulations","authors":"D. Law, Arun Sriniwas Selvamani, Luis Nava","doi":"10.1115/1.4063150","DOIUrl":"https://doi.org/10.1115/1.4063150","url":null,"abstract":"\u0000 Natural convective heat transfer can be enhanced through either fins or riblets, wall roughness elements, or the injection of bubbles in the flow. Bubble injections in a quiescent (pseudo-turbulent) liquid phase or an already turbulent liquid phase had been shown to enhance the natural convective heat transfer from literature. However, study of the combined effect of bubble size and gas volume fraction rather than individual effect on natural convective heat transfer enhancement for homogeneous bubbly flow is lacking. The present work intends to fill in that data gap through conducting numerical simulations to study the combined effect of bubble size and gas volume fraction on natural convective heat transfer enhancement. The present numerical work employs a validated interphase force models and the Eulerian-Eulerian model. ANSYS FLUENT is used to simulate a bubbly flow in a three-dimensional rectangular channel with a natural convective heat transfer. Bubbles ranging from micro to millimeter diameter with inlet gas volume fraction varied in the range of 0.351-3.725% are injected upward to a quiescent liquid phase in a rectangular channel with a heated left wall and a cooled right wall. The flow regime is homogeneous without bubble coalescence and breakup effect. Validated computational models are employed to study the combined effect of bubble size and gas volume fraction on heat transfer enhancement. A relation between Nusselt number, bubble Reynolds number, Rayleigh number, nondimensional bubble size, and inlet gas volume fraction is constructed using the power regression method.","PeriodicalId":15937,"journal":{"name":"Journal of Heat Transfer-transactions of The Asme","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90111014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Effects Of Variable Pressure Outlets For Array Jet Impingement Cooling With A Bidirectional Exit Air Scheme 可变压力出口对双向出口阵列射流冲击冷却的影响

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Journal of Heat Transfer-transactions of The Asme Pub Date : 2023-08-05 DOI: 10.1115/1.4063106

Michael Bonds, G. Iyer, S. Ekkad

{"title":"Effects Of Variable Pressure Outlets For Array Jet Impingement Cooling With A Bidirectional Exit Air Scheme","authors":"Michael Bonds, G. Iyer, S. Ekkad","doi":"10.1115/1.4063106","DOIUrl":"https://doi.org/10.1115/1.4063106","url":null,"abstract":"\u0000 Array jet impingement in conjunction with other cooling methods such as effusion cooling is used in gas turbine combustion zones to provide optimized cooling in the form of double wall cooling around a combustion chamber. Utilizing a transient liquid crystal (TLC) technique an experimental investigation into the effects of pressure gradients and single versus multiple exits for array jet impingement crossflow is evaluated in the form of a detailed heat transfer analysis. In this study, four pressure gradients to bias mass flow ratios as (1:1), (1:2), (1:3), and (1:0), two jet array configurations either inline or staggered with jet to jet spacings (x/D = y/D) of 1.4, 1.9, and 2.2, three jet to target distances (z/D) ranging from 2-4, and three Reynolds number from 5,000 to 15,000 are considered. In total, a test matrix of 72 different performance conditions was evaluated. Results are presented as local and area averaged Nusselt number plots along with local heat transfer coefficient contours. Overall, Nusselt number decreases with increased (z/D) and increased pressure gradient bias towards a single exit from (1:1) to (1:0). There is also slightly better performance from inline jet array configurations compared to staggered configurations.","PeriodicalId":15937,"journal":{"name":"Journal of Heat Transfer-transactions of The Asme","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84168375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Nonlinear Approximation For Mixed Convection Flow From A Vertical Plate With Exponentially Decaying Internal Heat Generation and Nonlinear Thermal Radiation 具有指数衰减内热和非线性热辐射的垂直板混合对流流动的非线性近似

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Journal of Heat Transfer-transactions of The Asme Pub Date : 2023-08-05 DOI: 10.1115/1.4063104

B. Jha, Gabriel Samaila

{"title":"Nonlinear Approximation For Mixed Convection Flow From A Vertical Plate With Exponentially Decaying Internal Heat Generation and Nonlinear Thermal Radiation","authors":"B. Jha, Gabriel Samaila","doi":"10.1115/1.4063104","DOIUrl":"https://doi.org/10.1115/1.4063104","url":null,"abstract":"\u0000 This study considered dynamic features of mixed convection flow over a vertical plate influenced by nonlinear thermal radiation and exponentially decaying internal heat generation. The importance of the nonlinear density variation with temperature (NDT) and convective heating is also analysed. The governing equations are transformed into ordinary differential equations (ODEs) using the similarity variables and solved in MAPLE 2022 by a Runge-Kutta Ferhlberg fourth-fifth order (RKF45) scheme. The results obtained show that, with an increase in the convection process, the internal heat generation convects more fluid away and consequently reduced the rate of heat flowing back into the plate. For a weak internal heat generation λx = 0.5, the plate temperature is less than one (1) and the heat is observed to flow from the plate into the fluid on the surface of the right plate. Furthermore, for weak convection and nonlinear thermal radiation effects, the rate at which the heat flows into the plate increases with the convective heat transfer parameter increase. However, for a strong nonlinear thermal radiation effect, the rate a which the heat flows out of the plate increases. The flow feature is not only governed by the rate of internal heat generation but the generation as well reverses the heat flow from the plate since the temperature of the right plate surface T is much higher than the fluid temperature on the left plate surface Tf.","PeriodicalId":15937,"journal":{"name":"Journal of Heat Transfer-transactions of The Asme","volume":"23 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81144345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Augmented Performance And Wake Management In Finned Tube Arrays Through Hierarchical Deployment Of Toe-Out Winglets 通过趾外小翼分层部署的翅片管阵列增强性能和尾流管理

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Journal of Heat Transfer-transactions of The Asme Pub Date : 2023-08-05 DOI: 10.1115/1.4063105

A. Arora, P. Subbarao

{"title":"Augmented Performance And Wake Management In Finned Tube Arrays Through Hierarchical Deployment Of Toe-Out Winglets","authors":"A. Arora, P. Subbarao","doi":"10.1115/1.4063105","DOIUrl":"https://doi.org/10.1115/1.4063105","url":null,"abstract":"\u0000 Downsizing the heat exchanger without compromising its heat exchange capacity is highly desirable for containing the box volume of a thermal management system. This investigation seeks to substantially boost the thermal compactness of a widely used gas-to-liquid heat exchanger, called finned tube arrays. For that purpose, winglet-type vortex generators are adopted. The novelty of the present study lies in the fact that it uses regression analysis to develop thermo-hydraulic functional correlations corresponding to three diverse design parameters of winglet-type vortex generators: the attack angle, the location and the geometric aspect ratio. In addition, enhancement in the wake-affected heat transfer is specifically examined, followed by a proof-of-concept study by making the best design(s) of vortex generators perform under widely varying operating conditions. Based on a thermo-hydraulic assessment of the generators' attack angle, 45-degrees is the limiting value of optimal attack angle. Although multiple winglet locations are found to deliver the desired thermal augmentation, a few locations incur disproportionate flow loss whereas majority locations facilitate linearized thermal augmentation. It is encouraging to find that the relative Colburn j-factor of the modified heat exchanger increases with the Reynolds number, despite the absolute values bearing an inverse correlation. While the highest augmentation in the average Colburn j-factor equals 44.1%, it is 150.1% over the wake-affected fin surface.","PeriodicalId":15937,"journal":{"name":"Journal of Heat Transfer-transactions of The Asme","volume":"59 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76679392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Dynamics of an Evaporating Drop Migrating in a Poiseuille Flow 泊泽维尔流中蒸发液滴迁移的动力学

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Journal of Heat Transfer-transactions of The Asme Pub Date : 2023-07-19 DOI: 10.1115/1.4063154

Anubhav Dubey, K. Sahu, Gautam Biswas

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Large Eddy Simulation Of Convective Heat Transfer In A Random Pebble Bed Using The Spectral Element Method 用谱元法模拟随机球床对流换热的大涡

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Journal of Heat Transfer-transactions of The Asme Pub Date : 2023-07-11 DOI: 10.1115/1.4062940

Tri Nguyen, D. Reger, Dezhi Dai, E. Merzari, Haomin Yuan, R. B. Jackson, G. Busco

{"title":"Large Eddy Simulation Of Convective Heat Transfer In A Random Pebble Bed Using The Spectral Element Method","authors":"Tri Nguyen, D. Reger, Dezhi Dai, E. Merzari, Haomin Yuan, R. B. Jackson, G. Busco","doi":"10.1115/1.4062940","DOIUrl":"https://doi.org/10.1115/1.4062940","url":null,"abstract":"\u0000 The development of Fluoride-Cooled High-Temperature Reactors (FHRs) has drastically increased the demand for an in-depth understanding of the heat transfer in packed beds cooled by liquid salts. The complex flow fields and space-dependent porosity found in a pebble bed require a detailed understanding to ensure the proper cooling of the reactor core during normal and accident conditions. As detailed experimental data is complicated to obtain for these configurations, high-fidelity simulation such as Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS) can be employed to create a high-resolution heat transfer numerical database that can assist in addressing industrial-driven issues associated with the heat transfer behavior of FHRs. In this paper, we performed a series of LES using CFD code NekRS to investigate the heat transfer for a bed of 1741 pebbles. The characteristics of the flow, such as average, rms, and time series of velocity and temperature, have been analyzed. Porous media Averages have also been performed. The simulation results show a good agreement between non-CHT and CHT. The generated data will be used to benchmark heat transfer modeling methods and local maxima/minima of heat transfer parameters. It will also be used for supporting convective heat transfer quantification for Kairos Power and benchmarking lower fidelity models.","PeriodicalId":15937,"journal":{"name":"Journal of Heat Transfer-transactions of The Asme","volume":"50 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82174769","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0