Faculty Profiles - FUCHIWAKI Masaki

Papers - FUCHIWAKI Masaki

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Mechanical Alloying Process Design by Using DEM Simulation and Experimental Validation Reviewed International journal

Boonthai Torsak, Nunthavarawong Peerawatt, Kowitwarangkul Pruet, Fuchiwaki Masaki

1st International Conference on Robotics, Engineering, Science, and Technology, RESTCON 2024Pattaya16 2024.02

Aerodynamic performances and efficiency of axial flow fan placed in cooling system Reviewed International journal

Kawano T., Fuchiwaki M.

Journal of Physics: Conference Series 2217 ( 1 ) 2022.05

Flow Patterns and Hysteresis Characteristic of a Poppet Valve Reviewed International journal

HIROSE Naoki, MASUDA Seiei, SHIMIZU Fumio, FUCHIWAKI Masaki, TANAKA Kazuhiro

JFPS International Journal of Fluid Power System ( The Japan Fluid Power System Society ) 15 ( 2 ) 53 - 61 2022.01

Language：English Publishing type：Research paper (international conference proceedings)

Previous studies on poppet valves have revealed that there are various flow patterns in the flow field around the valve body and that the flow pattern inside the poppet valve has various effects on the poppet valve. Recently, Masuda et al. have reproduced the hysteresis phenomenon on the pressure and flowrate characteristics of a poppet valve by CFD analysis coupled with an equation of motion. Unfortunately, their paper does not describe the detailed relationship between the hysteresis characteristics and the flow pattern. In this study, by succeeding and developing the work of Masuda et al. and including the results of previous studies, we have systematically organized the flow patterns of poppet valves into five types and clarified the relationship between the hysteresis characteristics and flow patterns. In addition, the flow force acting on the poppet valve connecting the hysteresis characteristic and the flow pattern has also been clarified.

DOI： 10.5739/jfpsij.15.53

CiNii Research

Growth Mechanism of a Vortex Structure Formed by a Sweeping Jet and a Main Flow Reviewed International journal

Kobayashi E., Fuchiwaki M., Raghu S.

American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM 2 2022.01

Pressure drop mechanisms in a cooling system enclosure Reviewed International journal

KAWANO Takashi, FUCHIWAKI Masaki

Journal of Fluid Science and Technology ( The Japan Society of Mechanical Engineers ) 17 ( 4 ) JFST0014 - JFST0014 2022.01

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

A potential way to reduce the noise generated by construction machinery cooling systems is to satisfy the flow rate required for cooling at lower fan speeds, and a promising approach to achieving this goal involves finding ways to reduce the pressure drop that occurs in the cooling system ventilation passages. Towards that end, approaches using computational fluid dynamics (CFD) have proven effective for estimating three-dimensional (3D) spatial pressure drops, but there have been few reports on actual loss mechanisms. In this study, the mechanisms of pressure drops that occur inside a cooling system enclosure and around exhaust port vents were investigated by capturing the flow discharged by the axial fan within the enclosure into the atmosphere via the exhaust port. We found that portions of the fan outlet flow divert significantly inside the enclosure and are exhausted at exhaust port outlets located some distance away from the fan. We also found that the pressure drops in such locations are larger than experienced by flow discharged via the shortest path. Since flows within the enclosure collide with each other and become unsettled around the exhaust port, turbulent kinetic energy increases, thus intensifying the pressure drop. Hence, by expelling the flow at the exhaust port via the shortest path without allowing it to mix chaotically inside the enclosure, the flow rate can be increased using the same fan speed.

DOI： 10.1299/JFST.2022JFST0014

Scopus

CiNii Research

Other Link： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85147710354&origin=inward

VORTEX STRUCTURE GENERATED BY A SWEEPING JET IN A CROSS FLOW AND ITS CREATION PROCESS Reviewed International journal

Fuchiwaki M., Raghu S.

American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM 1 2022.01

Three-dimensional Vortex Structure Formed by an Interaction Between a Main Flow and a Sweeping Jet

TANAKA Shoma, FUCHIWAKI Masaki

The Proceedings of the Fluids engineering conference ( The Japan Society of Mechanical Engineers ) 2022 ( 0 ) OS03-31 2022.01

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

A jet in crossflow formed by the interaction between the jet and a main flow is a typical unsteady flow. Jet in crossflow have been studied using experimental and numerical approaches. In particular, a sweeping jet in crossflow has recently attracted attention from the viewpoint of active flow separation control. A sweeping jet, which is an oscillating jet with high frequency and large amplitude, energy can be injected widely into the flow separation area. However, the flow fields formed by the interaction between the sweeping jet and the main flow and their flow mechanisms are poorly understood, it has not been put to practical use. Furthermore, the flow structure produced by the interaction between a sweeping jet and a main flow with different behaviors is very complex and difficult to understand. Therefore, it is extremely important to elucidate the flow structure generated by the interaction between a sweeping jet and a main flow. In this study, the detailed vortex structure generated by the interaction between the sweeping jet and the main flow was quantitatively examined using stereo PIV. The vortex structure behaves differently depending on the velocity ratio. The larger velocity ratio, a sweeping jet extends to the wake and develops near the wall.

DOI： 10.1299/jsmefed.2022.os03-31

CiNii Research

Three-dimensional Vortex Structure Formed by a Sweeping jet and Main flow

TANAKA Shoma, Fuchiwaki Masaki

The Proceedings of Mechanical Engineering Congress, Japan ( The Japan Society of Mechanical Engineers ) 2022 ( 0 ) S055p-10 2022.01

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

A sweeping jet produced by a fluidic oscillator has recently been examined from the viewpoint of flow separation control. A sweeping jet, which is an oscillating jet with high frequency and large amplitude, is generated by the internal structure of the oscillator, which eliminates the need for a drive unit. Sweeping jets have attracted attention as an active flow control device. Studies have proposed active flow control techniques for an airfoil based on sweeping jets. Most of these studies focused on the characteristics of the dynamic forces acting on the airfoil. However, the flow fields formed by the interaction between the sweeping jet and the main flow and their flow mechanisms are poorly understood, especially for the case where a sweeping jet is ejected into a main flow when a flow field is used to control flow separation. In this study, the detailed vortex structure generated by the interaction between the sweeping jet and the main flow was quantitatively examined using stereo PIV. The stream tube generated by the interaction between the sweeping jet and the main flow consists of two vortex tubes near the outlet of the sweeping jet at a location of 2.0d to 6.0d. At the wake over 10.0d, a pair of vortex tubes gradually separates.

DOI： 10.1299/jsmemecj.2022.s055p-10

CiNii Research

Vortex structure and growth process formed by a sweeping jet and a main flow International journal

Kobayashi Eisei, Fuchiwaki Masaki

The Proceedings of Mechanical Engineering Congress, Japan ( The Japan Society of Mechanical Engineers ) 2022 ( 0 ) S055-13 2022.01

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

Sweeping jet is a jet that oscillates at high velocity and is known to have a higher mixing effect. Therefore, it is attracting attention especially from the viewpoint of flow control. In fact, although reports have been made that contribute to control, the flow characteristics that directly contribute to control have not been clarified, and optimization and practical application have not progressed. Moreover, it has been shown that the flow splits in the wake and that a vortex structure similar to a single Jet in cross flow is emitted to the left and right near the exit of the sweeping jet, but the formation and decay processes that link them have not yet been clarified. In this study, we focus on the temporal changes of the flow structure generated near the exit of the inclined sweeping jet and elucidate them. In addition, numerical simulations are used to capture changes in spatial and temporal phenomena in detail.

DOI： 10.1299/jsmemecj.2022.s055-13

CiNii Research

Pressure Drop Caused by Diverting Flow in Cooling System and Its Optimization

KAWANO Takashi, FUCHIWAKI Masaki

The Proceedings of Mechanical Engineering Congress, Japan ( The Japan Society of Mechanical Engineers ) 2022 ( 0 ) S053-08 2022.01

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

One solution to reduce the cooling system noise generated by construction machinery is to drive the fan at low speed while ensuring the flow rate required for the cooling system. An approach to achieve this is to reduce the pressure drop that occurs in the flow path in the cooling system. Using CFD is effective for estimating the three-dimensional spatial pressure drop characteristics of the system, but the mechanism of pressure drop that occurs in the three-dimensional flow field has not been clarified. In this study, the flow field around the axial flow fan placed in the cooling system enclosure is visualized, and the mechanism of pressure drop that occurs in the three-dimensional flow field considering the actual configuration is clarified. With the default exhaust port, we found that portions of the fan outlet flow divert significantly inside the enclosure and are exhausted at exhaust port outlets located some distance away from the fan. With the optimized exhaust port, there are few diverting flow and the flow in the enclosure is discharged in a shorter route than the default exhaust port, so the pressure drop is reduced and the flow rate is increased. Hence, by expelling the flow at the exhaust port via the shortest path without allowing it to mix chaotically inside the enclosure, the flow rate can be increased using the same fan speed.

DOI： 10.1299/jsmemecj.2022.s053-08

CiNii Research

Pressure Fluctuation on the Blade of a Axial Fan Driven in a Cooling System Enclosure

KAWANO Takashi, FUCHIWAKI Masaki

The Proceedings of the Fluids engineering conference ( The Japan Society of Mechanical Engineers ) 2022 ( 0 ) OS07-15 2022.01

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

W Suppressing the pressure fluctuations distributed on the blade surface of an axial fan is applied as one of the means to reduce the noise generated in the cooling system of construction machinery. For that purpose, it is effective to use computational fluid dynamics (CFD) to capture the 3D vortex structure around a fan blade. However, while there have been many reports on the flow field formed around the blades of a fan alone or an axial fan with a duct-shaped shroud, the influence of the vortex structure formed at the actual operating point of the axial fan on the pressure fluctuation on the blade surface has not been sufficiently discussed. In this study, the three-dimensional vortex structure around the fan blade installed in the cooling system is investigated, and in particular, the influence of the wing tip leakage vortex on the pressure fluctuation on the fan blade surface is clarified. Wing tip leakage vortex that flow from forward in the direction of rotation of the fan interfere with a blade while oscillating periodically in the y-axis direction. The oscillation of the forward wing tip leakage vortex causes the separation position of the newly formed wing tip leakage vortex to change, and as a result, the pressure fluctuation increases at the tip of the blade suction surface near the separation position.

DOI： 10.1299/jsmefed.2022.os07-15

CiNii Research

Growth Process of Vortex Structure Formed by a Sweeping jet in Cross Flow near a Wall

KOBAYASHI Eisei, FUCHIWAKI Masaki

The Proceedings of the Fluids engineering conference ( The Japan Society of Mechanical Engineers ) 2022 ( 0 ) OS03-30 2022.01

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (bulletin of university, research institution)

The Fluidic Oscillator can permanently generate a high-velocity oscillating jet (Sweeping jet) and give a large fluctuation to the flow field without driving parts. Therefore, it is attracting attention as a new active flow control device. However, the flow characteristics that directly contribute to flow separation control have not been sufficiently clarified, and their optimization and practical application have not progressed. Therefore, in order to clarify the details of the flow characteristics that contribute to the flow separation control, it is necessary to clarify the flow structure generated by the sweeping jet that blows into the main flow from the wall surface．In this study, we clarify the growth process of the vortex structure generated by the interaction of the sweeping jet, which blows out from the wall at 30 degrees to the main flow, by numerical simulation. It is conducted to understand the complex and large-scale flow structure and its generation process generated by a sweeping jet in the main flow. The vortex structure forms one flow tube at z/d < 4.5 and splits into two at z/d > 4.5. Shear layer vortices with the same frequency as the oscillation frequency are generated in the stream tube, and after splitting into two, it is generated alternately to the left and right. After that, at z/d > 6.0, the shear layer vortex begins to collapse due to wall interference, and at z/d > 7.5 it transforms into discrete vortices.

DOI： 10.1299/jsmefed.2022.os03-30

CiNii Research

Vortex Ring Formed by a Butterfly Wing and Dynamic Forces

HAISHI Sei, FUCHIWAKI Masaki

The Proceedings of the Fluids engineering conference ( The Japan Society of Mechanical Engineers ) 2022 ( 0 ) OS03-27 2022.01

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

Butterfly generates unsteady dynamic fluid force with a pair of vortex rings. In order to elucidate the flight mechanism of butterflies, it is necessary not only to clarify the vortex rings formed around the wings but also elucidate the characteristics of the unsteady fluid force generated by the flapping motion. By applying the momentum theory to the vortex rings formed during flapping motion, it is possible to estimate the force generated by flapping motion. In this study, we reconstruct a pair of vortex rings formed by flapping motion based on a small number of visualization results and elucidate dynamic fluid force characteristics. A part of estimation result of Lift estimated by the rough shape vortex rings generated by downstroke and upstroke do not match with the direct measurement result. But not only the peak value of estimation result of Lift is near with the direct measurement result quantitatively but also the value of estimation result between upstroke is a small negative as well as the direct measurement result. Although there is a phase difference between the estimation result and direct measurement result, there is a qualitative and quantitative agreement between estimation results and direct measurement result. From those results, butterfly generate the unsteady dynamic Lift between downstroke, especially at butterfly spread wing maximum (t/T = 0.40). After that, the unsteady dynamic Lift decrease and become 0 at upstroke.

DOI： 10.1299/jsmefed.2022.os03-27

CiNii Research

Vortical Flow around Blades of an Axial Flow Cooling Fan in Construction Machinery

KAWANO Takashi, FUCHIWAKI Masaki

The Proceedings of the Fluids engineering conference ( The Japan Society of Mechanical Engineers ) 2021 ( 0 ) OS07-16 2021.01

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

The energy loss of the airflow generated by forced convection in the cooling system included in heavy construction machinery is due to friction and turbulence in its ventilation path, and its behavior is three-dimensional. Therefore, computational fluid dynamics (CFD) is effective in clarifying the three-dimensional energy loss mechanism, but there are few reports that three-dimensionally capture the flow field in the cooling system of construction machinery, especially including some components around the axial fan. In this study, the flow field of the entire cooling system was visualized by numerical simulation using ANSYS-CFX17.0, and the effect of the three-dimensional flow field formed around the blades of the axial flow fan on the fan performance was investigated. From the results of CFD analysis, the fan performance is inferior in the case of the axial fan only than in the case of the entire cooling system, which is consistent with the blockage effect of the wing tip leakage vortex limiting the air flowing into the impeller. The wing tip leakage vortex is large-scale and has a high vorticity, and is divided into leading edge of adjacent blade because it flows in the tangential direction while maintaining the same height as the wing tip.

DOI： 10.1299/jsmefed.2021.os07-16

CiNii Research

Pressure Drop Distribution in Three-Dimensional Flow Field Generated inside Cooling System Enclosure

KAWANO Takashi, FUCHIWAKI Masaki

The Proceedings of Mechanical Engineering Congress, Japan ( The Japan Society of Mechanical Engineers ) 2021 ( 0 ) S055-16 2021.01

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

A potential way to reduce cooling system noises generated by heavy construction machinery is to generate the required cooling airflow with a low fan speed, and one way to accomplish this is to optimize the ventilation path through which the airflow generated by the cooling fan passes. The computational fluid dynamics (CFD) approach would be effective for modeling the three-dimensional pressure drop characteristic of such systems. However there have been few reports aimed at clarifying the loss generation mechanisms or suggesting minimization methods based on flow field viewpoints. Accordingly, in this study, we visualize the three-dimensional (3D) flow field characteristics of an electric cooling fan system installed within the cooling enclosure of a heavy construction machinery and investigate the details of the system’s pressure drop mechanisms. The total pressure drop that occurs in the exhaust side enclosure accounts for 26% of the total pressure drop that occurs in the entire enclosure. In the exhaust side enclosure, the pressure drop is increased because the shape of the exhaust port is not corresponded to annular flow of the cooling fan wake.

DOI： 10.1299/jsmemecj.2021.s055-16

CiNii Research

Three-dimensional vorticial structure and generation process formed by the Sweeping jet in Cross flow

KOBAYASHI Eisei, FUCHIWAKI Masaki

The Proceedings of the Fluids engineering conference ( The Japan Society of Mechanical Engineers ) 2021 ( 0 ) OS03-01 2021.01

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

The sweeping jet has been attracted attention as active flow control and mixing acceleration devices. Especially, the studies of the flow separation control techniques using the sweeping jet have been reported recently. However, most of these results are mainly contribution of the dynamic forces and the study on the flow mechanism produced by a sweeping jet has not been understood sufficiently. Especially, the vortex structure and flow mechanism formed by the interaction between the sweeping jet and the main flow have not been understood sufficiently. The purpose of the present study is to investigate the detailed vortex structure produced by the interaction between the sweeping jet from the Fluidic Oscillator and the main flow by a numerical simulation.

DOI： 10.1299/jsmefed.2021.os03-01

CiNii Research

Internal Flow and Hysteresis Characteristic of the Poppet Type Pressure Control Valve

MASUDA Seiei, SHIMIZU Fumio, FUCHIWAKI Masaki, TANAKA Kazuhiro

TRANSACTIONS OF THE JAPAN FLUID POWER SYSTEM SOCIETY ( The Japan Fluid Power System Society ) 52 ( 1 ) 8 - 15 2021.01

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

Poppet valves are often used as a pressure / flow rate control valve for a hydraulic system. Much research has been conducted on the characteristics of poppet valves. Hysteresis characteristics have emerged in pressure-flow characteristic experiments of poppet valves designed and prototyped by the author. In order to clarify the mechanism of this hysteresis characteristic, we firconfirmed the reproduction of hysteresis and confirmed the validity of the research policy. Specifically, we investigated the internal flow by CFD analysis and examined the reproduction of hysteresis characteristics by CFD. The CFD software used is Simerics MP +, which allows CFD analysis to be combined with the valve's equation of motion. First, the precision of CFD analysis was verified by confirming that the experimental values of in the reference and calculated values were in good agreement. Furthermore, CFD steady flow analysis of the internal flow was performed, and the validity of the calculation results such as the flow patterns, flow coefficient, and flow force was examined. As a result, it was clarified that there is a flow pattern that can be roughly divided into two types of internal flow with different flow rates. Then, by changing the flow rate in a time-dependent manner using CFD, we were able to reproduce the hysteresis characteristics that are in good agreement with the experimental results.

DOI： 10.5739/jfps.52.8

CiNii Article

CiNii Research

Other Link： https://www.jstage.jst.go.jp/article/jfps/52/1/52_8/_pdf

Vortex structure near the wall surface formed by Sweeping jet

KOBAYASHI Eisei, FUCHIWAKI Masaki

The Proceedings of Mechanical Engineering Congress, Japan ( The Japan Society of Mechanical Engineers ) 2021 ( 0 ) S051-25 2021.01

Authorship：Corresponding author Language：Japanese Publishing type：Research paper (conference, symposium, etc.)

The Sweeping jet from the Fluidic Oscillator has been attracted attention as an active flow control device. The studies of the flow separation control techniques using the Fluidic Oscillator have been reported. However, most of these results area mainly contribution of the dynamic forces and the study of the flow mechanism produced by a Sweeping jet has not been understood sufficiently. Especially, it is not known the interaction between the Sweeping jet from the Fluidic Oscillator and the main flow and the detailed flow structure due to the interaction. The purpose of the present study is to investigate the detailed vortex structure produced by the interaction between the Sweeping jet from the Fluidic Oscillator and the main flow by a numerical simulation using ANSYS CFX.

DOI： 10.1299/jsmemecj.2021.s051-25

CiNii Research

Vorticity growth formed in vicinity of a wall on a moving elastic airfoil Reviewed International journal

Fuchiwaki M.

American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM 3 2021.01

Study on material removal mechanism for Cu-CMP on a patterned silicon wafer Reviewed International journal

Bakier M.A.Y.A., Matsumoto R., Fuchiwaki M., Khajornrungruang P., Suzuki K.

10th International Conference on Leading Edge Manufacturing Technologies in 21st Century, LEM 2021 243 - 245 2021.01

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Papers - FUCHIWAKI Masaki