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Jet Screech Reduction with Perforated Flat Reflector

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Journal of Thermal Science 2008年第3期17卷 224-227页

作者： Md.Tawhidul Islam Khan Kenbu Teramoto Shigeru matsuo Toshiaki Setoguchi Department of Mechanical Engineering Saga University

In the present experimental study, investigations have been carded out to evaluate the performance of the new control technique of jet screech with different perforated flat reflectors. Mainly two types of porous flat reflectors had been used in the experiment. One reflector （reflector-V） designed for placing the reflector surface vertical to the jet axis, when, another type of reflector （reflector-H） designed for placing the reflecting surface horizontal to the jet axis. In both cases the reflectors had been placed at the nozzle （base tube with uniform cross-sectional area） exit. The diameter of the reflector-V was 15D when the diameter of the reflector-H was 10D. The porous area of the reflector-V was 6D and 4.5D for reflector-H where D indicated the diameter of the nozzle exit. The placement of the reflector at the exit of the nozzle reduces the sound pressure at the nozzle exit. Thus the muted sound can not excite the unstable disturbance at the nozzle exit and the loop of the feedback mechanism disappeared, finally, the generation of jet screech be cancelled. The suction space located at the back side of the porous surface of the reflector-V improves the efficiency of the screech control technique. However, in the case of reflector-H, the receptivity process of feedback loop had been controlled by reducing the disturbances at the effective shock fronts as well as at the nozzle exit. The performance of the proposed method was verified with a flat reflector concept and good performance in jet screech suppression has been confirmed in the case of porous reflector.

关键词： Supersonic jet noise screech tone feedback loop noise reduction porous reflector

Transonic Moist Air Flow around a Circular Arc Blade with Bump

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Journal of Thermal Science 2009年第4期18卷 325-331页

作者： A.B.M.Toufique HASAN Shigeru matsuo Toshiaki SETOGUCHI Heuy Dong KIM Department of Mechanical Engineering Bangladesh University of Engineering and Technology Department of Mechanical Engineering Saga University School of Mechanical Engineering Andong National University

The unsteady phenomena in the transonic flow around airfoils are observed in the flow field of fan, compressor blades 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 experimentally and as a result, it was observed that the bump wall is effective for the control of shock wave on the airfoil. In the transonic 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 wave oscillation around a circular arc blade with or without a bump on the blade was investigated numerically. The results showed that the non-equilibrium condensation significantly reduced the flow field unsteadiness such as root mean of pressure oscillation and frequency compared to the case without the non-equilibrium condensation.

关键词： transonic flow moist air shock wave oscillation non-equilibrium condensation

A Review of Non-operative Treatments for Hepatocellular Carcinoma with Advanced Portal Vein Tumor Thrombus

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Journal of Clinical and Translational Hepatology 2017年第2期5卷 177-183页

作者： Michihisa Moriguchi mitsuhiro Furuta Yoshito Itoh Department of Molecular Gastroenterology and Hepatology Kyoto Prefectural University of Medicine Graduate School of Medical Science Kyoto Japan

Portal vein tumor thrombus (PVTT) frequently occurs with the progression of hepatocellular carcinoma (HCC) and is an important factor in determining the prognosis of *** many cases of HCC with advanced PVTT,treatment is difficult because the tumor has considerable extension into the liver,and portal hypertension is a frequent *** standard therapy for unresectable HCC with advanced PVTT is sorafenib therapy in patients with good hepatic ***,the outcomes of sorafenib therapy are not completely satisfactory,making the development of another therapy an urgent ***,this review aims to summarize non-operative treatments for HCC with advanced PVTT and discuss future perspectives based on those therapies,including therapies still being developed.

关键词： Keywords Hepatocellular carcinoma Medical therapy management Portal vein Thrombus

Propagation of Weak Pressure Waves against Two Parallel Subsonic Streams

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Journal of Thermal Science 2006年第2期15卷 135-139页

作者： Makiko YONAMINE Takanori USHIJIMA Yoshiaki MIYAZATO Mitsuharu MASUDA Hiroshi KATANODA Kazuyasu matsuo Department of Energy and Environmental Engineering Kyushu University Kasuga 816-8580 Japan Faculty of Environmental Engineering The University of Kitakyushu Kitakyushu 808-0135 Japan

In this paper, the characteristics of a pressure wave propagating against two parallel subsonic streams in a constant-area straight duct are investigated by one-dimensional analysis, two-dimensional numerical simulation, and experiments. Computations have been carried out by the two-dimensional Euler Equations using the Chakravarthy-Osher-type TVD scheme. Optical observations by the schlieren method as well as wall pressure measurements have been performed to clarify both the structure and the propagation velocity of pressure waves. The results show that the pressure wave propagating against the streams changes into a bifurcated pressure wave and the bifurcation occurs in the low speed streams. It is also found that the propagation velocity of the pressure wave obtained by the analysis and computation agrees well with the present experimental data.

关键词： compressible flow flow visualization internal flow compound waves compound choking

Optimization Study of a Coanda Ejector

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Journal of Thermal Science 2006年第4期15卷 331-336页

作者： H.D.Kim G.Rajesh T.Setoguchi S.matsuo School of Mechanical Engineering Andong National University388Songcheon-dongAndongGyeongbuk 760-749Korea Department of Mechanical Engineering Saga University1HonjoSaga 840-8502Japan

The Coanda effect has long been employed in the aerospace applications to improve the performances of various devices. This effect is the ability of a flow to follow a curved contour without separation and has well been utilized in ejectors where a high speed jet of fluid emerges from a nozzle in the ejector body, follows a curved surface and drags the secondary flow into the ejector. In Coanda ejectors, the secondary flow is dragged in the ejector due to the primary flow momentum. The transfer of momentum from the primary flow to the secondary flow takes place through turbulent mixing and viscous effects. The secondary flow is then dragged by turbulent shear force of the ejector while being mixed with the primary flow by the persistence of a large turbulent intensity throughout the ejector. The performance of a Coanda ejector is studied mainly based on how well it drags the secondary flow and the amount of mixing between the two flows at the ejector exit. The aim of the present study is to investigate the influence of various geometric parameters and pressure ratios on the Coanda ejector performance. The effect of various factors, such as, the pressure ratio, primary nozzle and ejector configurations on the system performance has been evaluated based on a performance parameter defined elsewhere. The performance of the Coanda ejector strongly depends on the primary nozzle configuration and the pressure ratio. The mixing layer growth plays a major role in optimizing the performance of the Coanda ejector as it decides the ratio of secondary mass flow rate to primary mass flow rate and the mixing length.

关键词： Coanda ejector compressible mixing layer flow dragging mixing length induced flow

Application of Optical Kerr Gate with SrTiO3 Crystal in Acquisition of Gated Spectra from a Supercontinuum

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Chinese Physics Letters 2012年第7期29卷 118-121页

作者： YAN Li-He JIA Sen SI Jin-Hai matsuo Shigeki CHEN Feng HOU Xun Key Laboratory for Physical Electronics and Devices of the Ministry of Education&Shaanxi Key Lab of Information Photonic Technique School of Electronics&Information EngineeringXi’an Jiaotong UniversityXi’an 710049 Department of Ecosystem Engineering The University of Tokushima2-1 MinamijosanjimachoTokushima 770-8506Japan

We investigate the optical Kerr effect of SrTiO3 (STO) crystal,of which the nonlinear response time was measured to be less than 200fs,while the nonlinear refractive index is estimated to be 2.16 × 10^(-15)cm^(2)/*** theoptical Kerr gate (OKG) technique with an STO crystal as the Kerr medium,we obtain narrow-bandwidth and symmetric gated spectra from a supercontinuum generated in distilled water by a femtosecond *** experimental results show superiority compared with the gated spectra obtained using OKG with CS2 as the Kerr medium,demonstrating that STO crystal is a promising OKG medium.

关键词： crystal SrTiO3 continuum

A Study of Under-expanded Moist Air Jet Impinging on a Flat Plate

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Journal of Thermal Science 2005年第4期14卷 334-340页

作者： Yumiko OTOBE Shigeru matsuo Masanori TANAKA Hideo KASHIMURA Heuy-Dong KIM Toshiaki SETOGUCHI Department of Control and Information Systems Engineering Kitakyushu National College of Technology5-20-1ShiiKokuraminami-kuKitakyushu-shiFukuoka 802-0985Japan Department of Mechanical Engineering Saga University1Honjo-machiSaga-shiSaga 840-8502Japan School of Mechanical Engineering College of Natural ScienceAndong National University388Song Cheon DongAndongKyung PookKorea

When a gas expands through a convergent nozzle in which the ratio of the ambient to the stagnation pressures is higher than that of the critical one, the issuing jet from the nozzle is under-expanded. If a flat plate is placed normal to the jet at a certain distance from the nozzle, a detached shock wave is formed at a region between the nozzle exit and the plate. In general, supersonic moist air jet technologies with non-equilibrium condensation are very often applied to industrial manufacturing processes. In spite of the importance in major characteristics of the supersonic moist air jets impinging to a solid body, its qualitative characteristics are not known satisfactorily. In the present study, the effect of the non-equilibrium condensation on the under-expanded air jet impinging on a vertical flat plate is investigated numerically in the case with non-equilibrium condensation, frequency of oscillation for the flow field becomes larger than that without the non-equilibrium condensation, and amplitudes of static pressure become small compared with those of dry air. Furthermore, the numerical results are compared with experimental ones.

关键词： compressible flow non-equilibrium condensation impinging jet simulation.

Configuration of Shock Waves in Two-Dimensional Overexpanded Jets

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Journal of Thermal Science 2003年第4期12卷 294-298页

作者： Masashi Kashitani Yutaka Yamaguchi Yoshiaki Miyazato Mitsuharu Masuda Kazuyasu matsuo Department of Aerospace Engineering National Defense Academy 1-10-20 Hashirimizu Yokosuka Kanagawa 239-8686 JapanDepartment of Aerospace Engineering National Defense Academy 1-10-20 Hashirimizu Yokosuka Kanagawa 239-8686 JapanDepartment of Energy and Environmental Engineering Kyushu University 6-1 Kasuga-Kouen Kasuga Fukuoka 816-8580 JapanDepartment of Energy and Environmental Engineering Kyushu University 6-1 Kasuga-Kouen Kasuga Fukuoka 816-8580 JapanDepartment of Mechanical Systems and Environmental Engineering The University of Kitakyushu 1-1 Hibikino Wakamatsu-ku Kitakyushu Fukuoka 808-0315 Japan

An experimental and analytical study has been carried out to obtain the clear understanding of a shock wave transition associated with a steady two-dimensional overexpanded flow. Two-dimensional inviscid theory with respect to a shock wave reflection is used in the present study on the characteristic of shock waves. The results obtained from the flow analysis are compared with those obtained from flow visualizations. It is shown that in the region of regular reflection, the angle of an incident shock wave becomes lower than that calculated by two shock theory with an increment in the ratio PJPb of the nozzle exit pressure Pc to the back pressure Pb. It is indicated that the configuration of shock waves in overexpanded jets is influenced by the divergent angle at the nozzle exit. Also it is shown from the flow visualization that a series of shock waves move into the nozzle inside with a decrease in pressure ratio Pc/Pb, even if the Pc/Pb is under overexpanded conditions.

关键词：振动波超声喷管可压缩流体膨胀喷射空气动力学

Characteristics of Spherical Shock Wave and Circular Pulse Jet Generated by Discharge of Propagating Shock Wave at Open End of Tube

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Journal of Thermal Science 2003年第3期12卷 245-249页

作者： Tsukasa Irie Tsuyoshi Yasunobu Hideo Kashimura Toshiaki Setoguchi Kazuyasu matsuo Department of Mechanical Engineering Kitakyushu National College of Technology ShiiKokuraminami-ku Kitakyushu 802-0985 Japan Department of Control and Information Systems Engineering Kitakyushu National College of Technology Shii Kokuraminami-ku Kitakyushu 802-0985 Japan Department of Mechanical Engineering Saga University Honjo Saga 840-8502 Japan Department of Mechanical Systems and Environmental Engineering Univ. of Kitakyushu1-1 Hibikino Wakamatsu-ku Kitakyushu808-0135 Japan

When the shock wave propagating in the straight circular tube reaches at the open end, the impulsive wave is generated by the emission of a shock wave from an open end, and unsteady pulse jet is formed near the open end behind the impulsive wave under the specific condition. The pulse jet transits to spherical shock wave with the increase in the strength of shock wave. The strength is dependent on the Mach number of shock wave, which attenuates by propagation distance from the open end. In this study, the mechanism of generating the unsteady pulse jet, the characteristics of the pressure distribution in the flow field and the emission of shock wave from straight circular tube which has the infinite flange at open end are analyzed numerically by the TVD method. Strength of spherical shock wave, relation of shock wave Mach number,distance decay of spherical shock wave and directional characteristics are clarified.

关键词： shock wave impulsive wave numerical analysis spherical shock wave TVD method