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| 1 | Flow Fields with Vortex in a Small Semi-open Axial Fan显示文摘In order to clarify the effect of tip clearance (TC) size on fan performance and the flow field at rotor outlet in asmall semi-open axial fan, the experimental investigation was carried out. The tip diameter of test fan rotor was180mm and test TC sizes were lmm (TC=1mm) and 4mm (TC=4mm). Fan characteristics tests were carried outfor two cases of TC size and three-dimensional velocity fields at rotor outlet were measured using a single slanthot-wire probe at four flow-rate conditions. As a result, it was found that the pressure - flow-rate characteristicscurves for two cases showed almost the same tendency. However, the ensemble averaged velocity profiles alongradial measurement stations of TC=4mm largely changed compared with that of TC=lmm in cases of smallflow-rate condition. From the phase-locked averaging results, it was also found that the vortex existed in the rotoroutlet flow field of high flow-rate condition for each TC case. Compared with the vortices for TC=1mm andTC=4mm, the vortex for TC=4mm was stronger than that for TC=1mm. | Norimasa. Shiomi Yoichi Kinoue Ying zi Jin Toshiaki Setoguchi Kenji Kaneko | 2009 | Journal of Thermal Science2009，18，4： | 12 |
| 2 | A Parametric Study for High-Efficiency Gas-Liquid Separator Design显示文摘由于它的简单几何学和很少维护,一个煤气的液体离心分离器广泛地在工业被使用。这些隔板以紧缩的设计,更低的压力落下和更高的能力比过滤器,洗气器或催促的人有可观的优点。一个煤气的液体离心分离器是利用旋转运动引起由密度差别把液体与气体分开的离心力和低压力的一台设备。有效、可靠的分离为最佳操作被要求。这些隔板经常通过仔细与复杂流动现象包含了被联系的一根插头管子由于分开的液体的乘火车在不到山峰效率被操作。象一些分离空格,翼出口角度,到插头直径比率的入口,为分离效率的模型和象物理尺寸的一个函数的压力落下那样的设计参数不在文学是可得到的。这离开设计者与对很小除了已知的图案和试验,继续。现在的学习的目的是执行参量的研究为煤气液体的隔板得到更高的效率。参量的研究在 CFD 工具的帮助下被执行了由改变隔板空间的长度分析一个离心分离器的分离表演。最好的设计参数被分析在获得的结果之上基于,正切的速度,旋涡,全部的压力损失。从现在的学习,几次尝试被做改进常规离心分离器的表演。 | S.Nagdewe J.K.Kwoon H.D.Kim D.S.Kim K.M.Kwak Toshiaki Setoguchi | 2008 | Journal of Thermal Science2008，17，3： | 11 |
| 3 | A Computational Study of Thrust Vectoring Control Using Dual Throat Nozzle显示文摘Dual throat nozzle (DTN) is fast becoming a popular technique for thrust vectoring. The DTN is designed with two throats, an upstream minimum and a downstream minimum at the nozzle exit, with a cavity in between the upstream throat and exit. In the present study, a computational work has been carried out to analyze the performance of a dual throat nozzle at various mass flow rates of secondary flow and nozzle pressure ratios (NPR). Two-dimensional, steady, compressible Navier-Stokes equations were solved using a fully implicit finite volume scheme. The present computational results were validated with available experimental data. Based on the present results, the control effectiveness of thrust-vectoring is discussed in terms of the thrust coefficient and the coefficient of discharge. | Choon Sik Shin Heuy Dong Kim Toshiaki Setoguchi Shigeru Matsuo | 2010 | Journal of Thermal Science2010，19，6： | 6 |
| 4 | Effects of Heterogeneous Condensation on the Transonic Flow Fields on a Bump Model显示文摘In the present study, effect of the heterogeneous condensation on the characteristics of shock wave generated on the bump model in the transonic flow field was investigated numerically. As a result, it was found that, for the flow field with steady adiabatic shock wave on the bump model, the condensation with heterogeneous nucleation has a strong effect on the whole flow field, and it reduced the strength of the shock. Furthermore, the total pressure loss was dependent on the concentration of the solid particles per unit volume. | Masanori TANAKA Shigeru MATSUO Toshiaki SETOGUCHI Heuy-Dong KIM | 2005 | Journal of Thermal Science2005，14，1： | 5 |
| 5 | Numerical Analysis of Chevron Nozzle Effects on Performance of the Supersonic Ejector-Diffuser System显示文摘The supersonic nozzle is the most important device of an ejector-diffuser system.The best operation condition and optimal structure of supersonic nozzle are hardly known due to the complicated turbulent mixing,compressibility effects and even flow unsteadiness which are generated around the nozzle extent.In the present study,the primary stream nozzle was redesigned using convergent nozzle to activate the shear actions between the primary and secondary streams,by means of longitudinal vortices generated between the Chevron lobes.Exactly same geometrical model of ejector-diffuser system was created to validate the results of experimental data.The operation characteristics of the ejector system were compared between Chevron nozzle and conventional convergent nozzle for the primary stream.A CFD method has been applied to simulate the supersonic flows and shock waves inside the ejector.It is observed that the flow structure and shock system were changed and primary numerical analysis results show that the Chevron nozzle achieve a positive effect on the supersonic ejector-diffuser system performance.The ejector with Chevron nozzle can entrain more secondary stream with less primary stream mass flow rate. | Fanshi Kong Yingzi Jin Toshiaki Setoguchi Heuy Dong Kim | 2013 | Journal of Thermal Science2013，22，5： | 5 |
| 6 | The Effect of Diffuser Angle on the Discharge Coefficient of a Miniature Critical Nozzle显示文摘Many researches on critical nozzles have been performed to accurately measure the mass flow rate of gas flow,and to standardize the performance as a flow meter.Recently,much interest is being paid on the measurement of very small mass flow rate in industry fields such as MEMS applications.However,the design and performance data of the critical nozzles obtained so far have been applied mainly to the critical nozzles with comparatively large diameters,and the works available on miniature critical nozzles are lacking.In the present study,a computational fluid dynamics method has been applied to investigate the influence of the diffuser angle on discharge coefficient of the miniature critical nozzles.In computations,the throat diameter of critical nozzle is varied from 0.2 mm to 5.0 mm and the diffuser angle is changed from 2 deg to 8 deg.The computational results are validated with some experimental data available.The results show that the present computational results predict appropriately the discharge coefficient of the gas flows through miniature critical nozzles.It is known that the discharge coefficient is considerably influenced by the diffuser angle,as the throat diameter of nozzle becomes small below a certain value.This implies that the miniature critical nozzles should be carefully designed. | Jae Hyung Kim Heuy Dong Kim Toshiaki Setoguchi | 2010 | Journal of Thermal Science2010，19，3： | 5 |
| 7 | Influence of Tip End-plate on Noise of Small Axial Fan显示文摘In this work, tip end-plate is used to improve the noise performance of small axial fans. Both numerical simulations and experimental methods were adopted to study the fluid flow and noise level of axial fans. Four modified models and the prototype are simulated. Influences of tip end-plate on static characteristics, internal flow field and noise of small axial fans are analyzed. The results show that on basis of the prototype, the model with the tip end-plate of 2 mm width and changed length achieved best noise performance. The overall sound pressure level of the model with the tip end-plate of 2 mm width and changed length is 2.4 dB less than that of the prototype at the monitoring point in specified far field. It is found that the mechanism of noise reduction is due to the decrease of vorticity variation on the surface of blades caused by the tip end-plate. Compared with the prototype, the static pressure of the model with the tip end-plate of 2 mm width and changed length at design flow rate decreases by 2 Pa and the efficiency decreases by 0.8%. It is concluded that the method of adding tip end-plate to impeller blades has a positive influence on reducing noise, but it may diminish the static characteristics of small axial fan to some extent. | MAO Hongya WANG Yanping LIN Peifeng JIN Yingzi Toshiaki Setoguchi Heuy Dong Kim | 2017 | Journal of Thermal Science2017，26，1： | 4 |
| 8 | Effect of Inlet Guide Vanes on the Performance of Small Axial Flow Fan显示文摘Effects of the inlet guide vanes on the static characteristics, aerodynamic noise and internal flow characteristics of a small axial flow fan are studied in this work. The inlet guide vanes with different outlet angle are designed,which are mounted on the casing and located at the upstream of the impeller of the prototype fan. Both steady and unsteady flow simulations are performed. The steady flow is simulated by the calculations of Navier-Stokes equations coupled with RNG k-epsilon turbulence model, while the unsteady flow is computed with large eddy simulation. According to the theoretical analysis, the inlet guide vanes with outlet angle of 60° are regarded as the optimal inlet guide vanes. The static characteristic experiment is carried out in a standard test rig and the aerodynamic noise is tested in a semi-anechoic room. Then, performances of the fan with optimal inlet guide vanes are compared with those of the prototype fan. The results show that there is reasonable agreement between the simulation results and the experimental data. It is found that the static characteristics of small axial flow fan is improved obviously after installing the optimal inlet guide vanes. Meanwhile, the optimal inlet guide vanes have effect on reducing noise at the near field, but have little effect on the noise at the far field. | LIU Yang LIN Zhe LIN Peifeng JIN Yingzi Toshiaki Setoguchi Heuy Dong Kim | 2017 | Journal of Thermal Science2017，26，6： | 4 |
| 9 | A Twin Unidirectional Impulse Turbine for Wave Energy Conversion显示文摘A twin unidirectional impulse turbine has been proposed in order to enhance the performance of wave energy plant.This turbine system uses two unidirectional impulse turbines and their flow direction is different from each other.However,the turbine characteristics have not been clarified to date.The performances of a unidirectional impulse turbine under steady flow conditions were investigated experimentally by using a wind tunnel with large piston/cylinder in this study.Then,efficiency of the twin impulse turbine have been estimated by a quasi-steady analysis using experimental results. | Manabu Takao Akiyasu Takami Shinya Okuhara Toshiaki Setoguchi | 2011 | Journal of Thermal Science2011，20，5： | 3 |
| 10 | Effect of Rotational Speed on the Stability of Two Rotating Side-by-side Circular Cylinders at Low Reynolds Number显示文摘Flow around two rotating side-by-side circular cylinders of equal diameter D is numerically studied at the Reynolds number 40≤ Re ≤200 and various rotation rate θ_i. The incoming flow is assumed to be two-dimensional laminar flow. The governing equations are the incompressible Navier-Stokes equations and solved by the finite volume method(FVM). The ratio of the center-to-center spacing to the cylinder diameter is T/D=2. The objective of the present work is to investigate the effect of rotational speed and Reynolds number on the stability of the flow.The simulation results are compared with the experimental data and a good agreement is achieved. The stability of the flow is analyzed by using the energy gradient theory, which produces the energy gradient function K to identify the region where the flow is the most prone to be destabilized and the degree of the destabilization. Numerical results reveal that K is the most significant at the separated shear layers of the cylinder pair. With Re increases,the length of the wake is shorter and the vortex shedding generally exhibits a symmetrical distribution forθ_i<θ_(crit), It is also shown that the unsteady vortex shedding can be suppressed by rotating the cylinders in the counter-rotating mode. | DOU Huashu ZHANG Shuo YANG Hui SETOGUCHI Toshiaki KINOUE Yoichi | 2018 | Journal of Thermal Science2018，27，2： | 3 |
| 11 | Unsteady Shock-Flow Characteristics in an Over-Expanded Rocket Nozzle显示文摘A numerical investigation of transient side-loads in an axisymmetric over-expanded thrust optimized contour nozzle is presented.These nozzles experience side-loads during start-up and shut-down operations,because of the flow separation at nozzle walls.Two types of flow separations such as FSS and RSS shock structure occur.A two-dimension numerical simulation has been carried out over an axisymmetric TOC nozzle to validate present results and investigate oscillatory flow characteristics for start-up processes.Reynolds Averaged Navier-Stokes equations are numerically solved using a fully implicit finite volume scheme.Governing equations are solved by coupled implicit scheme.Reynolds Stress turbulence model is selected.Present computed pressure at the nozzle wall closely matched with experiment data.A hysteresis phenomenon has been observed between these two shock structures.The transition from FSS to RSS pattern during start-up process has shown maximum nozzle wall pressure.Nozzle wall pressure and shear stress values have shown fluctuations during the FSS to RSS transition. The oscillatory pressure has been observed on the nozzle wall for high pressure ratio.Present results have shown that magnitude of the nozzle wall pressure variation is high for the oscillatory phenomenon. | Jong Sung Lee Huey Dong Kim Toshiaki Setoguchi Shigeru Matsuo | 2010 | Journal of Thermal Science2010，19，4： | 3 |
| 12 | Effect of the Uneven Circumferential Blade Space on the Performance of Small Axial Flow Fan显示文摘Effects of the uneven circumferential blade space on static characteristics and aerodynamic noise of a small axial flow fan are studied in this work.The blade angle modulation is adopted to design a series of unequally spaced fans,which have different maximum of modulation angular displacement.The steady flow is simulated by the calculations of Navier-Stokes equations coupled with RNG k-epsilon turbulence model,while the unsteady flow is computed with large eddy simulation.According to theoretical analysis,a fan with a maximum of modulation angular displacement of 6° is regarded as the optimal unequally spaced fan.The experiment of static characteristic is carried out in a standard wind tunnel and the aerodynamic noise of both fans is tested in a semi-anechoic room.Then,performances of the optimal unequally spaced fan are compared with those of the prototype fan.The results show that there is reasonable agreement between the simulation results and the experimental data.It is found that the discrete noise of the optimal unequally spaced fan is lower than that of the prototype fan at the near field monitoring point.This can be explained that the total pressure fluctuation of the optimal unequally spaced fan is much more regular than that of the prototype fan. | LIU Yang LIN Zhe LIN Peifeng JIN Yingzi Toshiaki Setoguchi Heuy Dong Kim | 2016 | Journal of Thermal Science2016，25，6： | 2 |
| 13 | Transonic Moist Air Flow around a Circular Arc Blade with Bump显示文摘The unsteady phenomena in the transonic flow around airfoils are observed in the flow field of fan, compressorblades and butterfly valves, and this causes often serious problems such as aeroacoustic noise and the vibration.In recent years, the effect of bump wall on the flow field around an airfoil has been investigated experimentallyand as a result, it was observed that the bump wall is effective for the control of shock wave on the airfoil. In thetransonic or supersonic flow field, a rapid expansion of moist air or steam gives rise to non-equilibrium condensation.In the present study, the effect of non-equilibrium condensation of moist air on the self-excited shock waveoscillation around a circular arc blade with or without a bump on the blade was investigated numerically. The resuitsshowed that the non-equilibrium condensation significantly reduced the flow field unsteadiness such as rootmean of pressure oscillation and frequency compared to the case without the non-equilibrium condensation. | A.B.M.Toufique HASAN Shigeru MATSUO Toshiaki SETOGUCHI Heuy Dong KIM | 2009 | Journal of Thermal Science2009，18，4： | 2 |
| 14 | Hydrogen Gas Filling into an Actual Tank at High Pressure and Optimization of Its Thermal Characteristics显示文摘Gas with high pressure is widely used at present as fuel storage mode for different hydrogen vehicles. Differenttypes of materials are used for constructing these hydrogen pressure vessels. An aluminum lined vessel and typicallycarbon fiber reinforced plastic (CFRP) materials are commercially used in hydrogen vessels. An aluminumlined vessel is easy to construct and posses high thermal conductivity compared to other commercially availablevessels. However, compared to CFRP lined vessel, it has low strength capacity and safety factors. Therefore,nowadays, CFRP lined vessels are becoming more popular in hydrogen vehicles. Moreover, CFRP lined vesselhas an advantage of light weight. CFRP, although, has many desirable properties in reducing the weight and inincreasing the strength, it is also necessary to keep the material temperature below 85 ℃ for maintaining stringentsafety requirements. While filling process occurs, the temperature can be exceeded due to the compression worksof the gas flow. Therefore, it is very important to optimize the hydrogen filling system to avoid the crossing of thecritical limit of the temperature rise. Computer-aided simulation has been conducted to characterize the hydrogenfilling to optimize the technique. Three types of hydrogen vessels with different volumes have been analyzed foroptimizing the charging characteristics of hydrogen to test vessels. Gas temperatures are measured inside representativevessels in the supply reservoirs (H2 storages) and at the inlet to the test tank during filling. | Md.Tawhidul Islam Khan Masanori Monde Toshiaki Setoguchi | 2009 | Journal of Thermal Science2009，18，3： | 2 |
| 15 | Influence of Coanda surface curvature on performance of bladeless fan显示文摘The unique Coanda surface has a great influence on the performance of bladeless fan.However,there is few studies to explain the relationship between the performance and Coanda surface curvature at present.In order to gain a qualitative understanding of effect of the curvature on the performance of bladeless fan,numerical studies are performed in this paper.Firstly,three-dimensional numerical simulation is done by Fluent software.For the purpose to obtain detailed information of the flow field around the Coanda surface,two-dimensional numerical simulation is also conducted.Five types of Coanda surfaces with different curvature are designed,and the flow behaviour and the performance of them are analyzed and compared with those of the prototype.The analysis indicates that the curvature of Coanda surface is strongly related to blowing performance,It is found that there is an optimal curvature of Coanda surfaces among the studied models.Simulation result shows that there is a special low pressure region.With increasing curvature in Y direction,several low pressure regions gradually enlarged,then begin to merge slowly,and finally form a large area of low pressure.From the analyses of streamlines and velocity angle,it is found that the magnitude of the curvature affects the flow direction and reasonable curvature can induce fluid flow close to the wall.Thus,it leads to that the curvature of the streamlines is consistent with that of Coanda surface.Meanwhile,it also causes the fluid movement towards the most suitable direction.This study will provide useful information to performance improvements of bladeless fans. | LI Guoqi HU Yongjun JIN Yingzi Toshiaki Setoguchi Heuy Dong Kim | 2014 | Journal of Thermal Science2014，23，5： | 2 |
| 16 | Numerical Simulation of Flow Characteristics in Micro Shock Tubes显示文摘Recently micro shock tubes have been widely used in many engineering and industrial fields, but the characteristics of unsteady flow are not well known to date in micro shock tubes. Compared to conventional shock tubes with macro scales, flows related to shock waves in micro shock tubes are highly complicated. Stronger viscous and dissipative interactions make shock wave dynamic behaviors significantly different from theoretical predictions. In the present study, a CFD work was applied to the unsteady compressible Navier-Stokes equations which were solved using a fully implicit finite volume scheme. The diaphragm pressure ratio and shock tube diameter were varied to investigate their effects on micro shock tube flows. Different wall boundary conditions were also performed to observe shock wave and contact surface propagation with no slip and slip walls. Detailed flow characteristics at the foot of shock wave and contact surface propagation were known from the present numerical simulations. | Guang Zhang Toshiaki Setoguchi Heuy Dong Kim | 2015 | Journal of Thermal Science2015，24，3： | 2 |
| 17 | Simulation and Experiment Research of Aerodynamic Performance of Small Axial Fans with Struts显示文摘Interaction between rotor and struts has great effect on the performance of small axial fan systems.The small axial fan systems are selected as the studied objects in this paper,and four square struts are downstream of the rotor.The cross section of the struts is changed to the cylindrical shapes for the investigation:one is in the same hydraulic diameter as the square struts and another one is in the same cross section as the square struts.Influence of the shape of the struts on the static pressure characteristics,the internal flow and the sound emission of the small axial fans are studied.Standard K-ε turbulence model and SIMPLE algorithm are applied in the calculation of the steady fluid field,and the curves of the pressure rising against the flow rate are obtained,which demonstrates that the simulation results are in nice consistence with the experimental data.The steady calculation results are set as the initial field in the unsteady calculation.Large eddy simulation and PISO algorithm are used in the transient calculation,and the Ffowcs Williams-Hawkings model is introduced to predict the sound level at the eight monitoring points.The research results show that:the static pressure coefficients of the fan with cylindrical struts increase by about 25%compared to the fan with square struts,and the efficiencies increase by about 28.6%.The research provides a theoretical guide for shape optimization and noise reduction of small axial fan with struts. | CHU Wei LIN Peifeng ZHANG Li JIN Yingzi WANG Yanping Heuy Dong Kim Toshiaki Setoguchi | 2016 | Journal of Thermal Science2016，25，3： | 2 |
| 18 | Effect of Nozzle Inlet Shape on Annular Swirling Flow with Non-Equilibrium Condensation显示文摘Recently,by combining a swirl flow with non-equilibrium condensation phenomena of condensate gas generated in a supersonic flow,a separating and extracting techniques of condensate gas have been developed.This technique can reduce the size of the device and don't use chemicals.In the present study,by using a non-equilibrium condensation phenomenon of moist air occurred in the supersonic flow in the annular nozzle composed of an inher body and an outer nozzle with a swirl,the possibility of separation of the condensable gas and the effect of shape of nozzle inlet on the flow field were examined numerically. | Yusuke FUKUSHIMA Shigeru MATSUO Toshiaki SETOGUCHI Norimasa SHIOMI Tokitada HASHIMOTO Heuy Dong KIM and Shen YU | 2015 | Journal of Thermal Science2015，24，4： | 1 |
| 19 | Passive Control of Condensation Shock Wave in Prandtl-Meyer Expansion Flow显示文摘In this paper,the effects of the passive technique by using the slotted wall on the characteristics of a condensation shock wave generated in a Prandtl-Meyer flow were investigated experimentally.Furthermore,in order to clarify the variation of condensation properties in the flow field.navier-Stoker equations were solved numerically using a 3rd-order MUSCL type TVD finite-difference scheme with a second-order fractional-step for time integration.Baldwin-Lomax odel was used as a turbulence model in the computations.From experimental results,it was found that the shock strength on the slotted wall became weak in compariosn with no passive case(solid wall),and the present passive technique was the most effective when a foot of the condensation shock wave was located at the middle of slotted wall.Furthermore.it was confirmed numerically that the passive technique was also effective for the unsteady condensation shock wave. | Shigeru Matsuo Masanori Tanaka Toshiaki Setoguchi Heuy-Dong Kim | 2003 | Journal of Thermal Science2003，12，1： | 1 |
| 20 | Development of two-way diffuser for fluid energy conversion system显示文摘 | Toshiaki Setoguchi Norimasa Shiomi | 2004 | Renewable Energy2004，29，10： | 1 |
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