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Shock Wave in Supersonic Moist Air Jet for a Low Pressure Ratio

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Journal of Thermal Science 2011年第4期20卷 289-293页

作者： Yumiko OTOBE Hideo KASHIMURA toshiaki setoguchi Kitakyushu National College of Technology Saga University

In the present study,a computational fluid dynamics work was performed to investigate the occurrence of the shock wave by condensation in supersonic moist air *** unsteady,compressible axisymmetric Navier-Stokes equation is solved by TVD(Total Variation Diminishing) scheme in this *** numerical simulations have been performed for low pressure ratio and various *** results show the occurrence of the shock wave in supersonic moist air jet for a low pressure ratio when Mach disk does not occur,depending on humidity of the air.

关键词： compressible flow axisymmetric flow shock wave condensation humidity

Effect of End Plates on the Performence of a Wells Turbine for Wave Energy Conversion

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Journal of Thermal Science 2006年第4期15卷 319-323页

作者： Manabu Takao toshiaki setoguchi YoichiKinoue KenjiKaneko Department of Mechanical Engineering Matsue National College of Technology 14-4 Nishiikuma-choMatsue-shiShimane 690-8518Japan Institute of Ocean Energy Saga University1 Honjo-machiSaga-shiSaga 840-8502Japan Department of Mechanical Engineering Saga University1 Honjo-machiSaga-shiSaga 840-8502Japan

In order to improve the performance of the Wells turbine for wave energy conversion, the effect of end plates on the turbine characteristics has been investigated experimentally by model testing under steady flow conditions. The end plate attached to the tip of the original rotor blade is slightly larger than the original blade profile. The characteristics of the Wells turbine with end plates have been compared with those of the original Wells turbine, i.e., the turbine without end plate. As a result, it has been concluded that the characteristics of the Wells turbine with end plates are superior to those of the original Wells turbine and the characteristics are dependent on the size and position of end plate. Furthermore, the effect of annular plate on the turbine performance, which encircles the turbine and is attached to the tip, was investigated as an additional experiment. However, its device was not effective in improving the turbine characteristics.

关键词： fluid machinery natural energy Wells turbine end plate wave energy conversion ocean energy.

Numerical Simulation of Flow Characteristics in Micro Shock Tubes

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Journal of Thermal Science 2015年第3期24卷 246-253页

作者： Guang Zhang toshiaki setoguchi Heuy Dong Kim Department of Mechanical Engineering Andong National University Department of Mechanical Engineering Saga University

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.

关键词： Micro shock tube Shock wave propagation Slip wall Unsteady flow CFD

Annular Supersonic Swirling Flows with Heterogeneous Condensation

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Journal of Thermal Science 2016年第6期25卷 518-525页

作者： Yusuke FUKUSHIMA Shigeru MATSUO Norimasa SHIOMI toshiaki setoguchi Graduate School of Science & Engineering Saga University Department of Advanced Technology Fusion Saga University Department of Mechanical Engineering Saga University Institute of Ocean Energy Saga University

In recent years,separating and extracting technologies of condensate gas have been developed by combining a swirl flow with non-equilibrium condensation phenomena of condensate gas generated in a supersonic *** technology can reduce the size of the device and does not use ***,there are many unresolved problems for performance of the separation,extraction and operating *** it is necessary to research further in order to improve the performance of the *** the present study,the numerical study was carried out to clarify the effect of the heterogeneous condensation on the characteristics of the swirling flow field in a supersonic annular nozzle,and the differences between homogeneous condensation and heterogeneous condensation in the flow *** the results,it is found that the condensation flow with a swirl affects the position of sonic line,the generating position of condensate and the radial distribution ratio of liquid phase.

关键词： condensation supersonic heterogeneous condensate viscosity chemicals generating annular nozzle regardless

Corner Separations around a NACA65 Blade in a Decelerating Flow (Experimental Investigations by Five-Hole Probe and PIV)

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Journal of Thermal Science 2013年第1期22卷 23-28页

作者： Yoichi Kinoue Ryutaro Ohhira Norimasa Shiomi toshiaki setoguchi Department of Mechanical Engineering Saga University Institute of Ocean Energy Saga University

In order to examine the fundamental characteristics of corner separation in a decelerating cascade flow,the experimental apparatus was made and separations around a NACA65 blade in a decelerating channel flow were ***-dimensional calculations show that the NACA65 cascade flow that has 45 *** turning,1.24 of solidity and 17 *** stagger angle is equivalent to the channel flow that has 14 *** stagger angle in terms of pitchwise blade *** investigation by five-hole probe shows that the accumulations of low energy fluid can be seen around the corner part and the overturning flow due to the secondary flow ***,as the periodicity of the blade wake in a pitchwise direction is comparably good,the wake of this channel flow is similar to the wake of the cascade flow for two pitch *** measurement results shows that a vortex pattern can be seen in the momentary streamline on the suction surface of the blade and in the averaged streamline on the perpendicular to both the suction surface and the endwall.

关键词： corner separation NACA65 blade decelerating channel flow five-hole probe PIV

The Effect of Diffuser Angle on the Discharge Coefficient of a Miniature Critical Nozzle

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Journal of Thermal Science 2010年第3期19卷 222-227页

作者： Jae Hyung Kim Heuy Dong Kim toshiaki setoguchi School of Mechanical Engineering Andong National UniversityAndong760-749Korea Department of Mechanical Engineering Saga University1HonjoSagaJapan

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 ***,much interest is being paid on the measurement of very small mass flow rate in industry fields such as MEMS ***,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 *** 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 *** 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 *** computational results are validated with some experimental data *** results show that the present computational results predict appropriately the discharge coefficient of the gas flows through miniature critical *** is known that the discharge coefficient is considerably influenced by the diffuser angle,as the throat diameter of nozzle becomes small below a certain *** implies that the miniature critical nozzles should be carefully designed.

关键词： Compressible Flow Critical Nozzle Compressible Flow Discharge Coefficient Diffuser Configuration Reynolds Number

Supersonic Moist Air Jet Impingements on Flat Surface

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Journal of Thermal Science 2010年第1期19卷 51-59页

作者： ALAM Miah Md.Ashraful MATSUO Shigeru setoguchi toshiaki Graduate School of Science & Engineering Saga University1Honjo-machiSaga-shiSaga 840-8502Japan Department of Mechanical Engineering Saga University1Honjo-machiSaga-shiSaga 840-8502Japan Institute of Ocean Energy Saga University1Honjo-machiSaga-shiSaga 840-8502Japan

Pronounced aeroacoustic resonances are exhibited in the flow field where a jet emerges from an orifice or a nozzle and impinges on a solid surface. One instance where such resonances are produced is in a high speed jet impingement, such as in the space launch vehicle systems, jet-engine exhaust impingement, and in the short take-off and vertical landing （STOVE） aircraft, etc. A highly unsteady flowfield leading to a drastic increase of noise level with very high dynamic pressure and thermal loads are noticed on nearby surfaces results dramatic lift loss, severe ground erosion and hot gas ingestion to the inlet in the jet engines. This highly unsteady behavior of the im- pinging jets is due to a feedback loop between the fluid and acoustic fields. In actual jet flow, the working gas may contain condensable gas such as steam or moist air. In these cases, the non-equilibrium condensation may occur at the region between nozzle exit and an object. The jet flow with non-equilibrium condensation may be quite different from that without condensation. Therefore, in this study, the effect of the non-equilibrium condensation of moist air on the axisymmetric under-expanded supersonic impinging jet on a vertical flat plate was investigated numerically.

关键词： compressible flow supersonic impinging non-equilibrium condensation oscillation

Hydrogen Gas Filling into an Actual Tank at High Pressure and Optimization of Its Thermal Characteristics

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Journal of Thermal Science 2009年第3期18卷 235-240页

作者： Md.Tawhidul Islam Khan Masanori Monde toshiaki setoguchi Department of Mechanical Engineering Saga University

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.

关键词： Hydrogen filling thermal characteristics of hydrogen storage CFRP storage tank

A Twin Unidirectional Impulse Turbine for Wave Energy Conversion

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Journal of Thermal Science 2011年第5期20卷 394-397页

作者： Manabu Takao Akiyasu Takami Shinya Okuhara toshiaki setoguchi Matsue College of Technology 14-4 NishiikumaMatsueShimane 690-8518Japan Saga University 1 HonjoSagaSaga 840-8502Japan

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 experimentaUy 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.

关键词： Fluid machinery impulse turbine wave energy conversion ocean energy.