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| 1 | Unstable Head-Flow Characteristic Generation Mechanism of a Low Specific Speed Mixed Flow Pump显示文摘This paper treats the flow instabilities in a mixed flow pump with a vaned diffuser. Test pump has a positive slope of a head-flow performance curve at 65% flow rate of BEP (Best Efficiency Point) because of a rotating stall. Dynamic Particle Image Velocimetry (PIV) and pressure fluctuation measurements are used for investigating the propagation mechanism of a rotating stall. It was found that unstable performance was caused by periodical large scale abrupt backflow generated from the vaned diffuser to the outlet of impeller. Further, the relation between the static pressure at the inlet of diffuser vane and the internal flow condition was clarified. From these experimental results, in order to improve the positive slope of a head-flow performance curve, to suppress the growth of strong vortex toward the inlet of diffuser vane was proved to be a key point. | Masahiro MIYABE Hideaki MAEDA Isamu UMEKI Yoshinori JITTANI | 2006 | Journal of Thermal Science2006，15，2： | 53 |
| 2 | A Review on Lithium-ion Power Battery Thermal Management Technologies and Thermal Safety显示文摘Lithium-ion power battery has become one of the main power sources for electric vehicles and hybrid electric vehicles because of superior performance compared with other power sources. In order to ensure the safety and improve the performance, the maximum operating temperature and local temperature difference of batteries must be maintained in an appropriate range. The effect of temperature on the capacity fade and aging are simply investigated. The electrode structure, including electrode thickness, particle size and porosity, are analyzed. It is found that all of them have significant influences on the heat generation of battery. Details of various thermal management technologies, namely air based, phase change material based, heat pipe based and liquid based, are discussed and compared from the perspective of improving the external heat dissipation. The selection of different battery thermal management(BTM) technologies should be based on the cooling demand and applications, and liquid cooling is suggested being the most suitable method for large-scale battery pack charged/discharged at higher C-rate and in high-temperature environment. The thermal safety in the respect of propagation and suppression of thermal runaway is analyzed. | AN Zhoujian JIA Li DING Yong DANG Chao LI Xuejiao | 2017 | Journal of Thermal Science2017，26，5： | 41 |
| 3 | Lessons from Rotor 37显示文摘NASA rotor 37 was used as a ’blind’ test case for turbomachinery CFD by the Turbimachinery Com-mittee of the IGTI. The rotor is a transonic compressor with a tip speed of 454 m/s (15OO ft/s) anda relatively high pressure ratio of 2.1. It was tested in isolation with a circumferentially uniform inletflow so that the flow through it should be steady apart from any effects of passage to passage geometry variation and mechanical vibration. As such it represents the simplest possible type of test forthree-dimensional turbomachinery flow solvers. However, the rotor still presents a real challenge to3D viscous flow solvers because the shock wave-boundary layer interaction is strong and the effects ofviscosity are dominant in determining the flow deviation and hence the pressure ratio. Eleven ’blind’solutions were submitted and in addition a ’non-blind’ solution was used to prepare for the exercise-This paper reviews the fiow in the test case and the comparisons of the CFD solutions with the testdata. Lessons for both the Flow Physics in transonic has and for the application of CFD to suchmachines are pointed out. | J.D. Denton(Whittle Laboratory Cambridge University Engineering Dept., Cambridge, England) | 1997 | Journal of Thermal Science1997，6，1： | 29 |
| 4 | Efficiency of Vertical Geothermal Heat Exchangers in the Ground Source Heat Pump System显示文摘Taking the fluid temperature distribution along the borehole depth into account,a new quasi-three-dirmensional model for vertical ground heat exchangers has been established,which provides a bettery understanding of the heat transfer processes in the geothermal heat exchangers,On this basis the efficiency of the borehole has been defined and its analytical expression derived.Comparison with the previous two-dimensional model shows that the quasi-three-dimensional model is more rational and more accurate to depict the practical feature of the conduction of geothermal heat exchanger,and the efficiency notion can be easily used to determine the inlet and outlet temperature of the circulating fluid inside the heat exchanger. | HeyiZeng NairenDiao 等 | 2003 | Journal of Thermal Science2003，12，1： | 30 |
| 5 | Modeling on Heat and Mass Transfer in Stored Wheat during Forced Cooling Ventilation显示文摘A mathematical model based on the theory of heat and mass transfer in porous media was developed to simulate the evolution of grain temperature and moisture content in a wheat storage bin during ventilation with cooling air at the constant temperature and humidity.Unlike the previous works on this aspect,the present work was not focused on cooling the stored grain by ventilation with ambient air,but with the refrigerated air.Validation was performed by comparing between predicted and measured grain temperature and grain moisture content for two cases.Predicted data were in reasonable good agreement with measured ones.The model and the parameter values used in the model are applicable for predicting temperature and moisture of stored grains under ventilation conditions. | Yuancheng WANG,Haifeng DUAN,Hao ZHANG and Zhaohong FANG College of Thermal Energy Engineering,Shandong Jianzhu University,Jinan 250101,China | 2010 | Journal of Thermal Science2010，19，2： | 27 |
| 6 | Effects of Momentum Ratio and Weber Number on Spray Half Angles of Liquid Controlled Pintle Injector显示文摘一个舵栓注射者为扼杀一台液体火箭引擎并且减少引擎重量是有益的。这研究为液体气体燃料在舵栓注射者的水花特征上以各种各样的注射条件探索动量比率和威伯数字的效果。一张液体表从一张中心舵栓嘴被注射,它被一口煤气的喷气从环形的差距打破。燃料的压力落下,和舵栓洞距离被看作控制变量;使用 0.1 1.0 液体注射作为为压力的一个酒吧落下,为为舵栓洞距离的煤气的喷气和 0.2 1.0 公里的压力落下的 0.010.2 酒吧。分泌物系数在 0.75 公里的舵栓洞距离前线性地被减少然后,系数稍微被增加。水花图象被一个互补金属氧化物半导体照相机与高分辨率捕获。然后,阴影和反映的图象被分析。水花分布被 patternator 从一个舵栓尖端与 50 公里的轴的距离测量。最后,角度有指数地减少的水花一半动量比率由威伯数字划分了的关联。另外,水花一半从水花分发的角度与从捕获的图象测量的那些相比被低估。 | Min Son Kijeong Yu Jaye Koo Oh Chae Kwon Jeong Soo Kim | 2015 | Journal of Thermal Science2015，24，1： | 26 |
| 7 | Abrasion characteristic analyses of solid-liquid two-phase centrifugal pump显示文摘Based on the solid-liquid two-phase mixture transportation test, the renormalization group (RNG) k-e turbulent model was utilized to simulate the solid-liquid two-phase turbulent flow in a centrifugal pump. By comparing the simulated and experimental results, inner flow features were revealed to improve the abrasion characteristic of the solid-liquid two-phase centrifugal pump. The influence of the solid phase on centrifugal pump abrasive performance is small when the particle volume fraction is less than 2.5%. The aggregation degree of the solid particles is enhanced as the particle diameter increases from 0.1 to 1 mm; however, the mixture density on the pressure side is reduced when the particle diameter increases to 1 mm for the impact of inertia. The wear on the hub is most severe for the shear stress on this position; it is also the largest. The wear characteristic is affected greatly by the parameters of the solid phase. The wear chracteristic can be optimized by decreasing the blade outlet angle. In the modified design, the blade angle is different, whereas the other geometric dimensions remain the same. The improved pump is simulated to contrast with the original pump. The results show that the values of mixture density and shear stress both decrease. The wear condition of the blade is improved to a certain extent. | LI Yi ZHU Zuchao HE Zhaohui HE Weiqiang | 2011 | Journal of Thermal Science2011，20，3： | 23 |
| 8 | Numerical Simulation of Flow in Centrifugal Pump with Complex Impeller显示文摘Based on the Navier-Stokes equations and the Spalart-Allmaras turbulence model,three dimensional turbulent flow fields in centrifugal pump with long-mid-short blade complex impeller are calculated and analyzed numerically.The relative velocity and pressure distributions in the flowpart are obtained.It is found that the flow in the passage of the complex impeller is unsymmetrical due to the joint action between volute and impeller.The back-flow region is at inlet of long-blade suction side,near middle part of long-blade pressure side and outlet of short-blade suction side.The flow near volute throat is affected greatly by volute.The relative velocity is large and it is easy to bring back flow at outlet of the complex impeller near volute throat.The static and total pressure rise uniformly from inlet to outlet in the impeller.At impeller outlet,the pressure periodically decreases from pressure side to suction side,and then the static pressure sharply rise near the throat.The experimental results show that the back flow in the impeller has an important influence on the performance of pump. | Bao-ling Cui Yong-gang Lin Ying-zi Jin | 2011 | Journal of Thermal Science2011，20，1： | 20 |
| 9 | Investigations on an Axial Flow Fan Stage subjected to Circumferential Inlet Flow Distortion and Swirl显示文摘The combined effects of swirl and circumferential inlet flow distortion on the flow field of an axial flow fan stage are reported in this paper. The study involves measurements at the inlet of the rotor and exit of the rotor and stator at design and off design now conditions. The study indicated that at the design flow condition, swirl had caused deterioration of the performance in addition to that caused by distortfou. Pressure rise imparted in the distortion zone is higher than in the free zone. The attenuation of distortion is high in the presence of swirl. | M. Govardhan K. Viswanath (Thermal Turbomachines Laboratory Department of Mechanical Engineering, Indian Institute of Technology, Madras 600 036, India ) | 1997 | Journal of Thermal Science1997，6，4： | 20 |
| 10 | The Experimental Study on Regenerative Heat Transfer in High Temperature Air Combustion显示文摘For the purpose of decomposing the processing gases CF4 from semiconductor manufacturers, ceramic honeycomb regenerative burner system is suggested by using the principle of HTAC. A simulated high temperature air combustion furnace has been used to determine the features of HTAC flames and the results of the decomposition of CF4. The preheat air temperature of it is above 900℃. The exhaust gas released into the atmosphere is lower than 150℃. Moreover, the efficiency of recovery of waste heat is higher than 80%, the NOx level in exhaust gas is less than 198 mg/m3 and the distribution of temperature in the furnace is nearly uniform. The factors influencing on heat transfer, temperature profile in chamber and NOX emission were discussed. Also some CF4 can be decomposed in this system. | Li JIA Jianshu LI | 2004 | Journal of Thermal Science2004，13，4： | 19 |
| 11 | Research on the Performance of Supercritical CO_2 Dry Gas Seal with Different Deep Spiral Groove显示文摘The performance of supercritical CO_2(SCO_2) dry gas seal(DGS) with different deep spiral groove is investigated with the thermal-fluid-solid coupling method. The performance parameters of DGSs with five different kinds of grooves are obtained. The influence of inlet temperature, inlet pressure, velocity and film thickness on performance is analyzed compared with air DGS. The average film pressure, open force and leakage decrease while the average face temperature and flow velocity increase as the spiral groove number increases. The average film pressure, average face temperature, open force and leakage of DGS with radial different deep groove are higher than those of DGS with circumferential different deep groove respectively under the same spiral groove number while the average flow velocity is the opposite. SCO_2 DGS can generate larger average film pressure, open force and leakage with lower average face temperature than air DGS. SCO_2 DGS could maintain better sealing performance despite larger leakage with the variations of inlet temperature, inlet pressure, velocity and film thickness. The variables hold a more remarkable influence on SCO_2 DGS compared with air DGS. | DU Qiuwan ZHANG Di | 2019 | Journal of Thermal Science2019，28，3： | 19 |
| 12 | Experimental Study on Preheated Combustion of Pulverized Semi-coke显示文摘In a test rig,pulverized semi-coke was preheated to 850℃in a circulating fluidized bed(CFB)and then cornbusted at 1100℃in a down-fired combustor(DFC).Experiments were conducted to reveal the effects of three secondary air nozzle cases(co-axial jet,top circular jet and wall circular jet)on the NO emission.The results show that the optimized secondary air nozzle can reduce NO emission.O_2 concentration profile is the major factor affecting NO generation and emission,which is led by the secondary air nozzle.The lower O_2 concentration led to the generation of lower initial NO.The NO emission at the exit of the DFC was reduced from 189 to 92mg/m^3(@6%O_2)with the decrease of initial generation.The peak of NO at 100 mm below the nozzle should be attributed to the oxidization of NH_3 in the syngas,rather than the oxidization of fuel-N in the char.The low and well-distributed O_2 concentration contributes to the reduction of initial NO,which helps to reduce the NO emission.The combustion effieiencies of the eases of the co-axial jet,the top circular jet,and the wall circular jet are97.88%,98.94%and 98.74%,respectively. | YAO Yao ZHU Jianguo LU Qinggang ZHOU Zuxu | 2015 | Journal of Thermal Science2015，24，4： | 19 |
| 13 | Experimental Study of Flow Patterns and Improved Configurations for Pulsating Heat Pipes显示文摘一系列实验在热输送的搏动的关上的循环(PHP ) 的三种类型上被执行,打算调查流动模式的各种各样的类型,并且开发为 PHP 的一些改进配置。光可视化结果显示那可能在那里存在三个流动模式,即水泡液体蛞蝓流动,半环形的流动和环形的流动,相应于不同工作条件。为给定的几何学并且一足够充满比率, PHP 为流动模式有自动调节的特征(从蛞蝓流动到半环形然后到环形的流动) 到会,增加的要求加热输入。二种特殊配置,有或者改变隧道直径的,与更厚的试管的一节装备的其它,被发现在建立并且维持工作液体的可靠循环有益。PHP 的热表演在工作条件的一个范围上被检验。与一致直径与正常 PHP 作比较,改进 PHP 的任何一个展出了更高热的性能。 | Shi LIU Jingtao LI Xiangyuan DONG Huanzhuo CHEN | 2007 | Journal of Thermal Science2007，16，1： | 18 |
| 14 | Performance Test and Flow Measurement of Contra-Rotating Axial Flow Pump显示文摘contra-rotating 转子的一个应用程序对对开发更高特定的速度的一个要求被建议了轴的流动泵。在现在的纸,使用 contra-rotating 转子的优点和劣势与转子定子的常规类型比较被描述,基于理论、试验性的调查。优点如下:(1 ) 泵内在地作为更小被设计缩放并且以更低的旋转速度。(2 ) 为有否定斜坡的流动率的一条稳定的头特征曲线出现。(3 ) 作为后面的转子,旋转速度作为前面转子的独立控制被改变,高效操作的更宽的范围被后面的转子速度控制除了前面转子速度控制获得。劣势如下:(1 ) 两倍柄系统的结构变得复杂。(2 ) 泵表演是劣等的在在是的流动率上,装载的后面的转子被削弱。(3 ) 片更强烈从后面的转子划相互作用到前面转子出现。当时,后面的转子设计是一把钥匙完成更高的泵性能。克服这些劣势的一些方法将向 contra-rotating 的更宽的用法更详细地被讨论各种各样的工业地里的轴的流动泵。 | Akinori Furukawa Toru Shigemitsu Satoshi Watanabe | 2007 | Journal of Thermal Science2007，16，1： | 18 |
| 15 | Experimental Study on Combustion Characteristics and NOX Emissions of Pulverized Anthracite Preheated by Circulating Fluidized Bed显示文摘A 30 kW bench-scale rig of pulverized anthracite combustion preheated by a circulating fluidized bed(CFB)was developed.The CFB riser has a diameter of 90 mm and a height of 1,500 mm.The down-fired combustion chamber(DFCC)has a diameter of 260 mm and a height of 3,000 mm.Combustion experiments were carried out using pulverized anthracite with 6.74%volatile content.This low volatile coal is difficult to ignite and burn out.Therefore,it requires longer burnout time and higher combustion temperature,which results in larger NOX emis-sions.In the current study,important factors that influence the combustion characteristics and NOX emissions were investigated such as excess air ratio,air ratio in the reducing zone,and fuel residence time in the reducing zone.Pulverized anthracite can be quickly preheated up to 800℃in CFB when the primary air is 24% of theoretical air for combustion,and the temperature profile is uniform in DFCC.The combustion efficiency is 94.2%,which is competitive with other anthracite combustion technologies.When the excess air ratio ranges from 1.26 to 1.67,the coal-N conversion ratio is less than 32%and the NOX emission concentration is less than 371 mg/m 3(@6%O2).When the air ratio in the reducing zone is 0.12,the NOX concentration is 221 mg/m 3(@6%O2),and the coal-N conversion ratio is 21%,which is much lower than that of other boilers. | WANG Jun ZHU Jian-guo LU Qing-gang | 2011 | Journal of Thermal Science2011，20，4： | 18 |
| 16 | Unsteady Internal Flow Conditions of Mini-Centrifugal Pump with Splitter Blades显示文摘Mini centrifugal pumps having a diameter smaller than 100mm are employed in many fields. But the design method for the mini centrifugal pump is not established because the internal flow condition for these small-sized fluid machines is not clarified and conventional theory is not suitable for small-sized pumps. Therefore, mini centrifugal pumps with simple structure were investigated by this research. Splitter blades were adopted in this research to improve the performance and the internal flow condition of mini centrifugal pump which had large blade outlet angle. The original impeller without the splitter blades and the impeller with the splitter blades were prepared for experiment. The performance tests are conducted with these rotors in order to investigate the effect of the splitter blades on performance and internal flow condition of mini centrifugal pump. On the other hand, a three dimensional unsteady numerical flow analysis was conducted to investigate the change of the internal flow according to the rotor rotation. It is clarified from the experimental results that the performance of the mini centrifugal pump is improved by the splitter blades. The blade-to-blade low velocity region was suppressed in the case with the splitter blades. In addition to that, the unsteady flows near the volute casing tongue were suppressed due to the splitter blades. In the present paper, the performance of the mini centrifugal pump is shown and the unsteady flow condition is clarified with the results of the numerical flow analysis. Furthermore, the effects of the splitter blades on the performance and the unsteady internal flow condition are investigated. | T. Shigemitsu J. Fukutomi K. Kaji T. Wada | 2013 | Journal of Thermal Science2013，22，1： | 18 |
| 17 | Computational Studies of Flow through Cross Flow Fans-Effect of Blade Geometry显示文摘This present paper describes three dimensional computational analysis of complex internal flow in a cross flow fan. A commercial computational fluid dynamics (CFD) software code CFX was used for the computation. RNG k-ε two equation turbulence model was used to simulate the model with unstructured mesh. Sliding mesh interface was used at the interface between the rotating and stationary domains to capture the unsteady interactions. An accurate assessment of the present investigation is made by comparing various parameters with the available experimental data. Three impeller geometries with different blade angles and radius ratio are used in the present study. Maximum energy transfer through the impeller takes place in the region where the flow follows the blade curvature. Radial velocity is not uniform through blade channels. Some blades work in turbine mode at very low flow coefficients. Static pressure is always negative in and around the impeller region. | M . GOVARDHAN D. LAKSHMANA SAMPAT | 2005 | Journal of Thermal Science2005，14，3： | 17 |
| 18 | Investigation of the Flow in the Impeller Side Clearances of a Centrifugal Pump with Volute Casing显示文摘The paper is concerned with the fluid flow in the impeller side clearances of a centrifugal pump with volute cas-ing.The flow conditions in these small axial gaps are of significant importance for a number of effects such as disk friction,leakage losses or hydraulic axial thrust to name but a few.In the investigated single stage pump,the flow pattern in the volute turns out to be asymmetric even at design flow rate.To gain a detailed insight into the flow structure,numerical simulations of the complete pump including the impeller side clearances are accom-plished.Additionally,the hydraulic head and the radial pressure distributions in the impeller side clearances are measured and compared with the numerical results.Two configurations of the impeller,either with or without balancing holes,are examined.Moreover,three different operating points,i.e.:design point,part load or overload conditions are considered.In addition,analytical calculations are accomplished to determine the pressure distri-butions in the impeller side clearances.If accurate boundary conditions are available,the 1D flow models used in this paper can provide reasonable results for the radial static pressure distribution in the impeller side clearances.Furthermore,a counter rotating wake region develops in the rear impeller side clearances in absence of balancing holes which severely affects the inflow and outflow conditions of the cavity in circumferential direction. | Bjrn-Christian Will Friedrich-Karl Benra Hans-Josef Dohmen | 2012 | Journal of Thermal Science2012，21，3： | 17 |
| 19 | Experimental Study on Heat Transfer and Pressure Drop Characteristics of Four Types of Plate Fin-and-TUbe Heat Exchanger Surfaces显示文摘ExperimentalStudyonHeatTransferandPressureDropCharacteristicsofFourTypesofPlateFin-and-TUbeHeatExchangerSurfaces￥H.J.Kang;W.L... | H.J. Kang W. Li H.Z. Li R.C. Xin W.Q. Tao(School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China) | 1994 | Journal of Thermal Science1994，3，1： | 17 |
| 20 | Numerical and Experimental Modelling of Gas Flow and Heat Transfer in the Air Gap of an Electric Machine显示文摘This work deals with the cooling of high-speed electric machines, such as motors and generators, through an air gap. It consists of numerical and experimental modeling of gas flow and heat transfer in an annular channel. Velocity and temperature profiles are modeled in the air gap of a high-speed test machine. Friction and heat transfer coefficients are presented in a large velocity range. The goals are reached acceptably using numerical and experimental research. The velocity field by the numerical method does not match in every respect the estimated flow mode. The absence of secondary Taylor vortices is evident when using time averaged numerical simulation. | Maunu KUOSA Petri SALLINEN Jaakko LARJOLA | 2004 | Journal of Thermal Science2004，13，3： | 16 |
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