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Article type: Cover
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Published: September 15, 2006
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Article type: Appendix
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Article type: Index
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A1-A6
Published: September 15, 2006
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Takayuki HAYASHIDA, Tatsuya SAKO, Koji INOUE, Yoshihiro MOTOMIYA, Kuni ...
Article type: Article
Session ID: 1312
Published: September 15, 2006
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A tire blowout would loose vehicle's stability suddenly, and it makes a driver upset and make him/her mistook steering operation or breaking operation. And there is a danger that a miserable accident would happen from a tire blowout of a vehicle running. However there are only a few reports about traffic accidents caused by a tire blowout. This study examined an accident caused by a tire blowout, which had all occupants (7 people) died. Authors report the process of the investigation for an accident which has no witness, and show an example the way of an investigation method.
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Takaaki NAKAMURA, Masayoshi TAKAKI
Article type: Article
Session ID: 1313
Published: September 15, 2006
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The petroleum refinery facilities have the emergency shutdown system in order to reduce a secondary seismic disaster which are a fire spread and a leak of combustible liquid and gas. However, many facilities decide about shutdown trigger level by an empirical judgment. It isn't considered quantitatively including loss by improper shutdown operation. In this study, the method for the estimation of suitable shutdown trigger level using the risk analysis is proposed.
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Gaku SHOJI, Yasunari UMESAKA
Article type: Article
Session ID: 1314
Published: September 15, 2006
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This paper describes the regulations related to the seismic-proof design of energy industrial facilities such as chemical plants. In Japan, the Building Standards Law, the High Pressure Gas Safety Law, the Fire Service Law, the Gas Utility Industry Law, the Electricity Utilities Industry Law, the Petroleum Pipeline Business Law regulate the design of hardware systems consisting of chemical plants. In addition to the Industrial Safety and Health Law, and the Law Relating to Prevention of Marine Pollution and Maritime Disaster, the Law on the Prevention of Disasters in Petroleum Industrial Complexes and Other Petroleum Facilities regulates the integrated design of software systems related to reduction of chemical-plant disasters
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Eiichi YAMASAKI
Article type: Article
Session ID: 1315
Published: September 15, 2006
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First, this report points out some problems of technical aids and equipments, for example, their unprofitability, unstandardization, and obscurity of needs ; and explains their legal bases. Second, the report explains what standardization means and what kind of technical aids and equipments are standardized by ISO and JIS. Finally, it discusses possibilities for Product Liability of technical aids and equipments: if their users modify them to meet their own needs, they may not be sufficiently compensated for their damages. A question remains regarding how to fit technical aids and equipments to their users, namely, the aged or disabled.
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Takashi KABE
Article type: Article
Session ID: 1316
Published: September 15, 2006
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There are principles and theories to attain safety technically. The basic of the law, is to protect people by good, justice, freedom and equality, etc. From there, the safety design technique and the social system related to safety are deduced. The guidelines ISO/IEC Guide 51 on safety and general design principles were verified, and it probed into the background of the way of thinking about the standard structure and category, and an international deductive technique was compared with conventional methods in Japan, and tried the considering what should be about the future safety regulation. The regulation in Japan about the machine is based on the Industrial Safety and Health Law as the control law. Safety is the matter of the fundamental human rights to have the proposition that the operator is protected. Originally, human rights are natural rights, and exist before the country which makes law at present are recognized.
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Kenjiro WATANABE, Tetsuyuki HIROE, Mitsuharu YAMAMOTO, Kazuhito FUJIWA ...
Article type: Article
Session ID: 1701
Published: September 15, 2006
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The knowledge of mechanical property changes for materials and structures after the transmission of strong shocks is of great importance in safety evaluation for accidental impact phenomena. In this study, explosively shocked plate specimens of aluminum A2017-T4 were successfully recovered without a large amount of damages due to the reflected expansion waves using momentum trap method. The transmitted shock waves were generated by the plane detonation waves in the high explosive PETN initiated using wire-explosion techniques. Two-dimensional hydro code, Autodyn-2D was applied to simulate the time-histories of stress waves in the specimens in order to determine the test conditions, thicknesses of explosive PETN, specimens and momentum traps and evaluate the experimental results. Micro Vickers hardness distributions in cross-sections were measured for recovered shocked specimens and compared with those of virgin specimen, showing significant increase of hardness for shocked specimens. Furthermore the recovered shocked specimens were machined to miniature tensile specimens of 2mm diameter and tensile tests are in progress, and a preliminary test result has indicated remarkable reduction of elongation and ductility for the shocked specimen.
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Satoshi OKAJIMA, Shinsuke SAKAI, Satoshi IZUMI
Article type: Article
Session ID: 1702
Published: September 15, 2006
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This study aims to develop a simplified method to update the failure probability of individual components using the evaluated residual life at inspections. The derivation of failure probability from evaluated residual life is based on Bayesian inference. In this formulation, we assume following situation: 1) A rough-classified database of the lifetime is available. 2) Target component was inspected one or more times. After the formulation is shown, effectiveness of this method is examined.
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Toshiaki WATANABE, Hironori MAEHARA, Shigeru ITOH
Article type: Article
Session ID: 1703
Published: September 15, 2006
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In recent years, a use for cryogenic fluids as a coolant has been increasing because of the industrial development of low temperature technology. Therefore, the use of the cryogenic pressure vessel and piping become general. LNG-tank, LN_2, O_2-tank at food factory and medical facilities are given for example. In the cryogenic pressure vessel and piping, reducing the thermal insulation of that by initial small damage, leads to an internal pressure rise and occurring of flashing, and causing secondary crush of pressure vessel and piping also. Then, we conducted the experiment, which imitates crush when the pressure vessel, which was filled with cryogenic temperature fluid, receives a shock loading. The inner pressure time history in such as this situation was measured.
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Satoshi KIMURA, Hidehiro HATA, Tetuyuki HIROE, Kazuhito FUJIWARA, Hide ...
Article type: Article
Session ID: 1704
Published: September 15, 2006
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In this study, an explosion combustion phenomenon of ammonium nitrate was used instead of a PETN explosive and a super-high-speed destruction phenomenon of metallic cylinder was analyzed. A powder of aluminum was added in ammonium nitrate, and an explosion combustion phenomenon was generated due to copper wire was ignited by high shock electric current. A metallic cylinder was destroyed by the phenomenon. The Photographs of the phenomenon was taken by a super-high-speed camera (IMACON468) and a high-speed video camera (HPV-1). The fragments of metallic cylinder were collected and were measured. Due to the result that ammonium nitrate was used was compared with the result that PETN explosive was used, a destruction phenomenon was analyzed. By this lecture, the result that examined a state of metallic cylinder destruction and destruction power of metallic cylinder by an explosion combustion phenomenon of ammonium nitrate was reported.
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Yosuke HEMUKI, Hideki HAMASHIMA, Shigeru ITOH
Article type: Article
Session ID: 1705
Published: September 15, 2006
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For the analysis of the shock wave of behavior and velocity, pressure propagating in PMMA, we performed 3 methods. To the first, we performed optical observation of the shock wave by the high-speed camera, captured the phenomenon of propagation of shock wave visually, and calculated the shock wave velocity simultaneously. To the second, the pressure measurement experiment with manganin gauge showed the force of the shock wave. To the third, numerical analysis by LS-DYNA complemented these data. In addition, pressure measurement experiment and numerical analysis data are in agreement comparatively.
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Masaharu FUJIWARA, Kazuhito FUJIWARA, Tetsuyuki HIROE, Hidehiro HATA
Article type: Article
Session ID: 1706
Published: September 15, 2006
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High explosives are useful material to generate great amount of energy in short time. Since controlling their releasing energy is hard, the use of explosive is limited to the breaking and crushing the tough structures and processing of bulk materials. However, the reduction of the explosive powder mass a shot and the pelets arranged at constant intervals make the handling safe, and that lead the new utility of the explosion. There are some difficulties to overcome when a small amount of explosive powder is used, such as the initiation regularity of explosives and the protection from gas damages. In this paper, the successive initiation of small explosive was tried by means of the wire explosion that is generated by the instant release of electric energy from capacitors, and the successful results were obtained under the controlled condition. The damages of surrounding devices were avoided with the initiating device which isolated the pressurized space from outside.
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Kentarou HAJIME, Kazuhito FUJIWARA, Makio ASAKAWA, Tetsuyuki HIROE, Hi ...
Article type: Article
Session ID: 1707
Published: September 15, 2006
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The sterilization for fungi and bacteria in some kinds of dry powder foods is limited to use because of heat sensitivity of them. The sterilization method using Impulsive load or shock waves has the capability to sterilize without heating and has been developed in our laboratory. Higher shock pressure can achieve more assured extinction, but has some problems such as the degradation of foods or the hardness of the treatment. The choice of energy sources is one of points to make the method come up to the industrial level. Safety and easiness are also important factors to develop the practical system. In this paper, as an instance of the weaken limit of shock sterilization, the powder was impacted by mechanical hammers and the efficiency of sterilization was studied. It was found that the iterative impacts showed the effect although the efficiency was insensibly low at one hit.
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Hironori MAEHARA, Shigeru ITOH
Article type: Article
Session ID: 1708
Published: September 15, 2006
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This research is to inject nonflammable agent into wood pressurizing, and to develop the fireproofing technology of wood. The technology uses the underwater shock wave. The underwater shock wave destroy the bordered pit membrane of the organization in wood, and open the pass way of moisture, and improve the permeability of nonflammable agent. As a result, it succeeded to inject effectively the nonflammable agent into the wood. Then the wood injected the nonflammable agent was evaluated by using the cone calorimeter by the heat build-up examination (ISO5660-1) based on the Building Standard Law of Japan. We report on the evaluation.
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Ayumi TAKEMOTO, Youzou MIBUKA, Masayoshi IWAHARA, Shigeru ITOH
Article type: Article
Session ID: 1709
Published: September 15, 2006
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The heating is used for sterilization generally. On the other hand, there is a large demand for non-heating sterilization technology in the many fields. An underwater shock wave causes the high pressure that makes the bacteria inactivate under non-heating environment. In this research, Saccharomyces cerevisiae was used under three kinds of conditions. That is, the pressure level of the underwater shockwave and the causing of the fermentation by the glucose processing. After the underwater shock wave loading and incubating for 24 hours, the sterilization rate was calculated from the number of colonies. As a result, a high sterilization effect of S. cerevisiae in the comparatively low shock wave pressure level was obtained by the glucose processing.
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Yosuke MORITA, Atsuhiko SHINTANI, Tomohiro ITO
Article type: Article
Session ID: 3701
Published: September 15, 2006
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The overturning possibility for the vehicle running at very high speed subjected to the basic excitation is investigated. One-half of the whole vehicle is analytically modeled. The vehicle consists of the body and the truck. Each of them has 3 degrees of freedom (horizontal, vertical and rolling direction). Considering a swaying stopper, the horizontal spring between the body and the truck is treated by a nonlinear spring. The vehicle vibrational behavior is caluculated when the vehicle is subjected to the actual seismic input in horizontal and vertical directions simultaneously. The possibility of rollover of the vehicle is evaluated by "risk rate of rollover". The risk rate of rollover of the running vehicle is investigated both in a straight line and a curve.
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Koichi YANAGAWA, Hitoshi TSUNASHIMA, Yoshitaka MARUMO, Akira MATSUMOTO ...
Article type: Article
Session ID: 3702
Published: September 15, 2006
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Light Rail Vehicles (LRVs) adopt various technologies different from conventional trams, such as independent rotating wheels, oating car structure, resilient wheels, etc. The purpose of these technologies is to make low oored vehicles and to realize progressively barrier free. The vehicle structure is deeply related to the vehicle dynamics, so we started the measurement of vehicle dynamics and wheel/rail contact of LRVs. And the analysis of the dynamics of LRV is done by using Multi body dynamics program SIMPACK.
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Takayoshi KAMADA, Maki Hosaka, Masao NAGAI
Article type: Article
Session ID: 3703
Published: September 15, 2006
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In recent years, buildings have become taller so the horizontal vibration of the elevator becomes a important problem. Many studies have been conducted for the vibration control of the cage or the main rope. Deformation and vibration of the travelling cables which supply the electric power and control signal through relay box also become a big problem. In this paper, dynamic characteristics of the travelling cables are investigated by FEM analysis using viscoelastic model. Parameter identification was conducted and deformation of the cable was simulated. Influences of the temperature and attached position were investigated and reasonable results were obtained.
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Hiroshi Sakuyama, Shigeyuki Kojima, Etsunori Fujita, Shigehiko Kaneko, ...
Article type: Article
Session ID: 3704
Published: September 15, 2006
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In this study, it is aimed to improve a vibration control performance by using lightweight and maintenance-free magnetic spring and magnetic damper.
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Makoto Komiyama, Yohei Michitsuji, Yoshihiro SUDA, Akira MATSUMOTO, Ya ...
Article type: Article
Session ID: 3705
Published: September 15, 2006
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Railway truck is necessary to have excellent curving performance as well as high speed hunting stability, but generally they are contrary to each other. "Active-bogie-steering (ABS) Bogie", is one of the methods to realize the compatibility between curving performance and hunting stability. ABS bogie has active steering mechanism only between car body and bogie frame, and bogie frame is steered by actuators toward "radial steering position", which realizes no "bogie angle shortage". In this paper, more detailed study and evaluation for ABS bogie will be presented. Bogie control strategies which minimize a certain cost function including contact lateral forces for leading-outside wheels of each bogie is proposed. According to the numerical simulation with multi-body dynamics software, the effectiveness of the proposed bogie mechanism and control are proved.
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Junya YAMAKAWA, Nobuhiro KURAHASHI, Keiji WATANABE
Article type: Article
Session ID: 3706
Published: September 15, 2006
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A method of optimal wheel torque allocation and steering angle determination for independent wheel drive vehicles is presented. Appropriate torque allocation to each wheel is an essential factor for efficient drive and better vehicle performance. Equations to determine optimal wheel torque and steering angles have been derived by minimizing the evaluation function which is defined by the friction loss due to the interaction between wheels and the ground. Solving the equations with the specifications of an eight-wheel vehicle, the combination of optimal wheel torque and steering angles on climbing slope and steady turn were obtained.
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Takumi HASEGAWA, Kimiyoshi TAKADA
Article type: Article
Session ID: 3707
Published: September 15, 2006
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It is known that the fuel pulsation caused by fuel pump or injectors is generated for vehicle fuel line. This fuel pulsation caused noise and deterioration of engine performance. Therefore, estimating this pulsation in an early stage of development is hoped. So, we are developing a fuel pulsation analysis method by using 1D fluid flow analysis software. This paper describes that fuel pulsation of vehicle fuel line models with and without a fuel damper was calculated by this method and effectiveness by using fuel damper was predicted. Comparing the calculation results with the experimental results, the effectiveness of this method was confirmed.
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Satoshi SOMEYA, Koji OKAMOTO
Article type: Article
Session ID: 3708
Published: September 15, 2006
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Any wind instrument can sound due to the vibration of the air, expiration flow inside of the wind instrument. In case of a trumpet or a clarinet, a mouth or a reed helps to sound variable tones. In case of a flute, there is no mechanical vibration. We would like to investigate more detail about the flow and the vibration with sound inside or outside of the flute, in order to understand the mechanism of the wind instrument and to aid in the manufacture of the good instrument. In this report, a Japanese traditional bamboo flute was used in the experiment. The dynamic PIV technique was applied to measure the vibration. 2 kinds of experiments were done. The Argon-gas flow with different tone inside/outside of the bamboo flute was measured using a high frequency pulse laser. Oil mist was used as the tracer particles. Then, we also tried to measure the flow in bamboo flute when a human player played, using a CW laser and the water-mist as the tracers. We successfully measured that the periodical flow near a hole of the bamboo flute went out from and came into the flute at 200-500Hz dependent on the tone.
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Taiki Korematsu, Hideki Narahashi, Toshiyuki Hayase, Ryuhei Yamaguchi
Article type: Article
Session ID: 3709
Published: September 15, 2006
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The flow structure in the right-angled branch with double side branch has been experimentally studied in laminar steady flow with laser doppler anemometer and particle image velocimetry. In the study of the right-angled branch with single side branch, it was clarified that the velocity periodically oscillates in the side branch, and the Strouhal number is independent of cross-sectional area ratio, the flow division ratio of main branch to side branch, and the Reynolds number. Periodical oscillation appears in the separation shearing layer, and a factor of oscillation is high shear rate. In this study, the factor of oscillation phenomena was examined in right-angled branch with double side branch.
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Ryo MORITA, Fumio INADA
Article type: Article
Session ID: 3710
Published: September 15, 2006
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A steam control valve causes vibration of the piping when the opening is in the middle condition. For the rationalization of maintenance and management in the plant, the cause of vibrations should be clarified and the valve should be improved. In previous researches, we have cralified a distinctive pressure fluctuations that may cause the vibrations and suppressed that fluctuations to improve the valve body. But, as we have adopted the air, not steam, as fluids in our previous researches, the effects of condensation and differences of fluids are not considered. In this report, we conducted the steam experiments and CFD calculations around the valve flow, and clarified the effects of the condensation and the differences of the fluids. As a result, the pressure fluctuations that is observed in the air experiment and CFD occurred in steam experiments and CFD calculations, and did not find much differences about the occurrence region of pressure fluctuations.
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Masahiro WATANABE, Makoto OHYAMA, Hideaki TANAKA
Article type: Article
Session ID: 3711
Published: September 15, 2006
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This paper deals with an experimental study on flow-induced vibrations of flexible bellows structures. The vibration characteristics of bellows structures are examined experimentally with changing pitch, number of convolution and damping ratio. The fluid flow around the vibrating convolutions is visualized, and the dynamic behavior and structure of the vortex street are examined. As a result, it is found that flow-induced vibration occurs when the reduced velocity based on the pitch is over 2.0, and mean Strohal number based on pitch is about 0.48. Two types of lock-in vibration modes, in-phase and out-of-phase vibration modes, with different flow (vortex street) patterns were observed in the experiments.
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Tomomichi NAKAMURA
Article type: Article
Session ID: 3712
Published: September 15, 2006
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An estimated damping ratio is used to evaluate the occurrence of the fluid-elastic instability. However, many structures contain some nonlinearity, especially in their damping ratios. Then, it is a great problem which value is used for the estimation of the critical flow velocity. As the nonlinear damping usually shows the increasing trend to the vibration amplitude of tubes, vibrations of a tube with the negative damping due to the fluid flow are calculated for some parametric cases, where the structural damping component has a linear relation to the tube-amplitude. The results show the tube plays as a kind of limit cycle in a few seconds, and the final amplitude depends on the nonlinear trend of the structural damping. It is suggested that this nonlinear damping trend is used for the design estimation of the fluid-elastic instability.
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Dong-Yeul SONG, Kensaku MATSUMOTO, Haruo TAMAKI
Article type: Article
Session ID: 3713
Published: September 15, 2006
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In this study, a new approach for estimation of river flow state such as water level, flow velocity and flow as well as stability of bridge is proposed using time series analysis of vibration signal measured using accelerometer mounted on the bridge during flood. In detail, a simple vibration model consisting of river flow and bridge pier is prepared, and a discrete model is developed, and then the correlation between mechanical parameters and time series model parameters is discussed. Next, the actually measured vibrations signal during usual time and flood are investigated in time region, and are analyzed using the corresponding discrete time series model. It is therefore revealed that the river flow state and the stability of bridge can be estimated by monitoring the change in AR parameters of the measured time series vibration signal.
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Mikael A. LANGTHJEM, Niels OLHOFF
Article type: Article
Session ID: 3714
Published: September 15, 2006
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A simply supported beam of circular cross sections is assumed to be set into resonant oscillations by the action of a distributed external force. The oscillations generate sound. The aim of the present work is to determine the optimal radius distribution of the beam, which minimizes the emitted acoustic power, under constraints on the resonance frequency and beam volume. This optimization problem is solved numerically.
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Keiko ANAMI, Noriaki ISHII, Tatsuya OKU, Satoshi SASAKI, Naoto TERAKAW ...
Article type: Article
Session ID: 3715
Published: September 15, 2006
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In order to evaluate the Coulomb frictional effects experimentally, a simple experiment was conducted with the 1/13-scale 3-dimensional model of Folsom dam Tainter-gate. With a small Coulomb friction added to each side of the skinplate, the model gate was initially forced to vibrate and its dynamic response was carefully observed. In the present experiment a rubber sheet was attached to the two sides of the skinplate and in contact with the channel walls, thereby providing a small frictional resistance. The bottom end of the skin plate was fixed to the channel floor with a thin string, and the gate was raised to the point where the string suddenly broke. Thus the gate was impulsively forced to vibrate, where the initial displacement could be adjusted by changing the strength of string.
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Keiko ANAMI, Tatsuya OKU, Noriaki ISHII, Shingo TANINO, Yoshihiro KONY ...
Article type: Article
Session ID: 3716
Published: September 15, 2006
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This study presents a semi-empirical evaluation procedure for determining the hydrodynamic flow-rate-variation pressure induced by an inclined circular-arc skinplate undergoing rotational vibration around the trunnion pin while positioned above a curved dam crest. First, the hydrodynamic flow-rate-variation pressures acting on the inclined circular-arc skinplate above the curved dam crest due to the rotational vibration around the trunnion pin were measured in detail. Then, the resulting experimental values were carefully compared with the calculated hydrodynamic pressure for a vertical flat weir plate above a flat channel floor. Then, the measured hydrodynamic flow-rate-variation pressure on a circular-arc skinplate above a curved dam crest can be evaluated by empirically adjusting the flow-rate variation coefficient and the gate submergence to reservoir depth ratio in the previously developed calculation procedure for the hydrodynamic pressure induced by a vertical flat weir plate above a flat channel floor.
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Keiko ANAMI, Noriaki ISHII, Tatsuya OKU, Satoshi Sasaki
Article type: Article
Session ID: 3717
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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The flow-induced coupled-mode self-excited vibration of huge Tainter gates were theoretically analyzed, and it was confirmed the validity by the model experiments. However, the experimental results have suggested that the instantaneous flow-rate coefficient does not correspond to 1:1 to vibration of a gate. Therefore, in order to clarify the characteristic of the instantaneous discharge flow from the gate bottom, we had many experiments. However, there was a problem on measurement accuracy in response to the influence of the contraction flow. This paper present the test results for variations in flow rate from the gate bottom. The instantaneous discharge velocity caused by the gate vibration was measured at the down-stream rather than the gate bottom, by LDV. The characteristics of instantaneous discharge flow were examined in detail, and the dependability of gate opening was also examined.
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Keiko ANAMI, Noriaki ISHII, Charles W. KNISELY, Tatsuya OKU
Article type: Article
Session ID: 3718
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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Tainter gates are frequently used for water-level regulation in impoundment dams. One of the massive Tainter gates at the Folsom Dam failed during operation on July 17, 1995 in California. After the gate failure, the 4 remaining Folsom Tainter gates were reinforced. However, it is not clear whether the gates have the complete dynamic stability by the reinforcement. In order to prevent another gate failure, it is necessary to surely examine the dynamic stability of the reinforced Folsom Tainter gate. For this purpose, first, the natural vibration characteristics of the reinforced Folsom Tainter gate were revealed by the experimental modal analysis. Next, the essential dynamic instability of reinforced gate was calculated by using the measured natural vibration characteristics. Furthermore, based on the calculated results, the basic concepts for the completely stable long-term operation of the reinforced Folsom Tainter gate was examined.
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Ryu ONUMA, Masahiro WATANABE, Hideaki TANAKA
Article type: Article
Session ID: 3719
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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This paper deals with suppression of sloshing in a vessel by a flexible bulkhead which divides the container vertically into two sections. The sloshing mode is separated into two modes by the bulkhead ; the one is the sloshing mode of liquid column in a U-tube, and the other is the sloshing mode in the each separated container. The effect of flexible bulkhead on the suppression of sloshing is examined with changing the thickness of the bulkhead plate experimentally. The flow pattern in the container is visualized.
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Hiromitsu HAMAKAWA, Kouji Komatsu, Eiichi NISHIDA, Tohru FUKANO
Article type: Article
Session ID: 3720
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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In the present paper the attention is focused on effect of the fin pitch on vortex shedding from the tube banks with serrated fin. The tube banks were installed rigidly in the test section of the wind tunnel. We measured the spectrum of velocity fluctuation and the freestream velocity in the simulated tube banks which has same pitch ratio as that of a boiler heat exchanger. The vortex of high frequency component mainly formed within the fin-tube banks and the other vortex of low frequency component was in the wake of the fin-tube banks. As the fin pitch became small, the Strouhal number of vortex in the wake of fin-tube banks decreased. The applicability of the equivalent diameter obtained by a single fin-tube to the fin-tube banks was examined. The measured Strouhal number of vortex within the fin-tube banks agreed well with Strouhal number obtained from Fitz-hugh's map for bare-tube banks.
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Masaya KONDO
Article type: Article
Session ID: 3721
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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A model on amplitude of the lock-in oscillation of a cylinder is proposed. The model is based on one-dimensional equations of motion and the empirical relationship between cylinder trajectory and reduced velocity. The model qualitatively predicts the effects of the reduced velocity and the damping on the amplitude.
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Masaki TAGAWA, Souichi SASAKI, Hidechito HAYASHI, Yoshio KODAMA
Article type: Article
Session ID: 3722
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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Relation between the wake characteristics and the aerodynamic noise of a flat blade with serrate leading edge was analyzed based on a prediction theory. The effect on decreasing of the noise level of the serrate flat blade was quantitatively estimated by measuring a width and a diameter of wake vortex. When angle of attack was 30 degrees, the discrete frequency noise level of a serrate flat blade became 1.4dB smaller than that of the flat plate blade. It clarified experimentally that when the diameter of wake vortex became small by the serrated blade, the noise level generated from serrate flat plate blade became small.
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Sadao AKISHITA
Article type: Article
Session ID: 3723
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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This paper describes optimal distribution of surface impedance for aerodynamic noise from a thin wing. Incidence turbulence noise generated by flow-wing interaction and its reduction by utilizing finite impedance are discussed in this paper. Green's function is introduced to formulate the dipole sound field of wing with perforated surface. After the effect of finite impedance is formulated for the wing noise generated by incident turbulence flow, numerical examples of the effect are shown finally, which prove the effectiveness of the optimization of impedance distribution for reducing the wing noise.
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Ryosuke OHYA, Yoshihiro IMURA, Munetake HIRAO, Mizue MUNEKATA, Hiroyuk ...
Article type: Article
Session ID: 3724
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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The purpose of this study is to elucidate the aerodynamic sound generated from the symmetric airfoils of six types and airfoil of NACA0010 and the flow structures around the airfoils with the attack angle in uniform flow. The sound pressure level was measured with the low noise wind tunnel. The flow visualization around the airfoils was also performed with the wind tunnel. From the investigation on the attack angle with various symmetric airfoils, it is found that overall SPL is larger when the Karman's vortex street in the wake is more stable in a low angle of attack.
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Kaoru KAWAHARA, Takamasa UDOH, Mizue MUNEKATA, Hiroyuki YOSHIKAWA, Hid ...
Article type: Article
Session ID: 3725
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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The purpose of this study is to investigate the characteristics of aerodynamic sound generated from wake interference of circular cylinder and airfoil vane located in tandem and to clear the generation mechanism of the sound source with discrete frequency. The effects of the interval between the cylinder and the airfoil on the characteristics of aerodynamic sound are investigated by acoustic measurement, flow visualization and exploration test of sound source. The relation between the flow field and the sound field with discrete frequency noise (DFN) is shown, and then it is found that the downstream airfoil works as the sound source of DFN, which has the frequency of vortex shedding from the upstream cylinder, when the interval of two bodies is longer than a critical distance.
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Masafumi MIYATA, Yoshinari HAYASHI
Article type: Article
Session ID: 3726
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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A two-dimensional rectangular bar having roundness at a corner can generate a considerable level of high frequency sounds for a relatively narrow region of angle of attack. The frequency is one order higher than that generated by the usual Karman vortex and basically proportional to the free stream velocity, but the proportional coefficient changes stepwise into the higher mode with increase of the velocity. The generation of the sound is directly related to the reattachment of the separated boundary layer from the rounded corner. The characteristics of the emitted sound and the behavior of the reattaching boundary layer on the bar surface are investigated experimentally under the free stream velocity from 7m/s to 21m/s.
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Taku HONDA, Yuichi TSUKAMOTO, Hiroshi YOKOYAMA, Akiyoshi IIDA, Chisach ...
Article type: Article
Session ID: 3727
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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The aim of this investigation is to clarify effect of edge shape on aerodynamic noise radiated from backward-facing step. To understand relationship between edge shape and tonal noise, wind tunnel experiments were carried out with a backward-facing step and small bump. In order to understand the effect of edge shape of backward-facing step, acoustic field around the edge of step was calculated. The acoustics filed depended on the edge shape of the back-step. The result of wind tunnel experiments showed the tonal-noise was not observed in the case of the back-step with large round-edge.
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Akihiro KIMURA, Masaharu NISHIMURA, Tomonobu GOTO, Masahiro SUGESAWA, ...
Article type: Article
Session ID: 3728
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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Characteristics of aerodynamics random noise generated from a cavity were studied in this report, by wind tunnel experiments and CFD simulations. It was found out that there were two types of noise generated from a cavity. One is a broadband random noise mainly generated at the downstream edge, and another is a narrow band noise caused by the pressure pulse feedback mechanism. Voltex generators set at the upstream edge was found to be effective to reduse the narrow band noise. and a filter set at the downstream edge was effective to reduse both types of noises.
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Shouta MAEHARA, Masaya SHIGETA, Seiichiro IZAWA, Yu FUKUNISHI
Article type: Article
Session ID: 3729
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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An active flow control to reduce the aerodynamic noise generated by a flow over a cavity is attempted, using a device which consists of a loudspeaker and a resonator. Only the phases of operating signals for the speakers are changed when the fluctuations from the leading edge of the cavity, which are 180 degrees out-of-phase in the spanwise direction. As a result, the maximum noise reduction 20dB is achieved.
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Eri Fukuyama, Yuichi Tsukamoto, Taku Honda, Akiyoshi IIDA, Chisachi Ka ...
Article type: Article
Session ID: 3730
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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The aim of this investigation is to develop a low noise wind tunnel with low temperature drift. The pressure sensitive paint (PSP) is the most suitable method for measurement of surface pressure. However, an accuracy of PSP strongly depends on the temperature of the circumstance. Since the temperature drift of conventional low-noise wind tunnel, it is difficult to utilize PSP in low-noise wind tunnel. The suction typed low-noise wind tunnel was developed, which had a high air-tightness chamber. An un-uniformity of the velocity distribution was 0.1% in the cross section. An aerodynamic sound can be measured in the open test section of the suction typed wind tunnel with a high air-tightness chamber. The temperature drift was only 0.1 degree. As a result, the suction typed low-noise wind tunnel can be applied to correlation measurement of surface pressure and aerodynamic sound with PSP.
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Yoshihiro KATO, Igor MEN'SHOV, Yoshiaki NAKAMURA
Article type: Article
Session ID: 3731
Published: September 15, 2006
Released on J-STAGE: August 01, 2017
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A method for performing aeroacoustic simulation, where the acoustic field is computed by the equations split from the flow field, is applied to the acoustic field of an object on the large flat surface. The acoustic field is obtained by the equations defined by the difference between the compressible and the incompressible flow equations. The acoustic equations are solved by the finite volume method with the fourth order WENO scheme. A rectangular cylinder with the limited width and an automobile rear-view mirror are calculated and the acoustic fields are investigated. The aspects in the near fields are different, while the emission patterns in the far fields are similar. The result of the rear-view mirror shows that the fluctuations of the regions with low acoustic density located downstream both outside and inside the mirror cause the acoustic emission.
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