研究者詳細 - 内山　知実

Collection of oil mist using a baffle plate-type mist trap

Takamure, K; Uchiyama, T; Ando, S; Kato, H; Nakayama, H

APPLICATIONS IN ENGINEERING SCIENCE 15 巻 2023年9月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Applications in Engineering Science

In the field of metal cutting, the cutting oil scatters in air as a microscale oil mist, which adversely affects the work environment. A baffle plate-type mist trap was manufactured as simple equipment for collecting oil mist floating in air. The oil mist collection rate and pressure loss were determined using experiments and numerical simulations while varying the number of baffle plates and inflow velocity of air. The experimental results showed that the pressure drop increased with the number of baffle plates, whereas the oil mist collection rate improved. It was also clarified that larger particles can be collected as the number of baffle plates increased. Numerical simulations showed that a high amount of oil mist was trapped upstream of the second baffle plate, and the baffle plate placed further downstream had minimal contribution to oil mist collection. In both the experiments and numerical simulations, the oil mist collection efficiency was the highest when six baffle plates were arranged. This is because the pressure drop increases depending on the number of baffle plates, whereas the mist collection rate is almost constant when many baffle plates are placed.

DOI： 10.1016/j.apples.2023.100137

Inactivation characteristics of a 280 nm Deep-UV irradiation dose on aerosolized SARS-CoV-2

Takamure, K; Iwatani, Y; Amano, H; Yagi, T; Uchiyama, T

ENVIRONMENT INTERNATIONAL 177 巻 2023年7月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Environment International

A non-filter virus inactivation unit was developed that can control the irradiation dose of aerosolized viruses by controlling the lighting pattern of a 280 nm deep-UV (DUV)-LED and the air flowrate. In this study, the inactivation properties of aerosolized SARS-CoV-2 were quantitatively evaluated by controlling the irradiation dose to the virus inside the inactivation unit. The RNA concentration of SARS-CoV-2 remained constant when the total irradiation dose of DUV irradiation to the virus exceeded 16.5 mJ/cm2. This observation suggests that RNA damage may occur in regions below the detection threshold of RT-qPCR assay. However, when the total irradiation dose was less than 16.5 mJ/cm2, the RNA concentration monotonically increased with a decreasing LED irradiation dose. However, the nucleocapsid protein concentration of SARS-CoV-2 was not predominantly dependent on the LED irradiation dose. The plaque assay showed that 99.16% of the virus was inactivated at 8.1 mJ/cm2 of irradiation, and no virus was detected at 12.2 mJ/cm2 of irradiation, resulting in a 99.89% virus inactivation rate. Thus, an irradiation dose of 23% of the maximal irradiation capacity of the virus inactivation unit can activate more than 99% of SARS-CoV-2. These findings are expected to enhance versatility in various applications. The downsizing achieved in our study renders the technology apt for installation in narrow spaces, while the enhanced flowrates establish its viability for implementation in larger facilities.

DOI： 10.1016/j.envint.2023.108022

Simultaneous Measurement of Volumetric Flowrates of Gas-Liquid Bubbly Flow Using a Turbine Flowmeter

Uchiyama, T; Miyamoto, S; Horie, K; Takamure, K

SENSORS 23 巻 ( 9 ) 2023年4月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Sensors

The flowrate measurement of the gas–liquid two-phase flow frequently observed in industrial equipment, such as in heat exchangers and reactors, is critical to enable the precise monitoring and operation of the equipment. Furthermore, certain applications, such as oil and natural gas processing plants, require the accurate measurements of the flowrates of each phase simultaneously. This study presents a method that can simultaneously measure the volumetric flowrates of each phase of gas and liquid two-phase mixtures, Qg and Ql, respectively, without separating the phases. The method employs a turbine flowmeter and two pressure sensors connected to the pipes upstream and downstream of the turbine flowmeter. By measuring the rotational speed of the rotor and the pressure loss across the flowmeter, the flowrate of the two-phase mixtures Qtp = (Qg + Ql) and the gas volumetric flowrate ratio β = (Qg/Qtp) are determined. The values of Qg and Ql are calculated as βQtp and (1 − β)Qtp. This study also investigates the measurement accuracies for air–water two-phase flows at 0.67 × 10−3 ≤ Qtp ≤ 1.67 × 10−3 m3/s and β ≤ 0.1, concluding that the full-scale accuracies of Qtp, β, Qg, and Ql are 3.1%, 4.8%, 3.9%, and 3%, respectively. These accuracies either match or improve the accuracies of similar methods reported in the literature, indicating that the proposed method is a viable solution for the determination of phase-specific flowrates in gas–liquid two-phase mixtures.

DOI： 10.3390/s23094270

Wake characteristics of sphere with circular uniaxial through-hole arranged perpendicularly to streamwise direction

Takamure, K; Kato, H; Uchiyama, T

POWDER TECHNOLOGY 415 巻 2023年2月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Powder Technology

In this study, the wake characteristics of a sphere with a uniaxial through-hole (that is, vented sphere) and that of a sphere without a through-hole (that is, basic sphere) are investigated to clarify the effect of the uniaxial through-hole on the vortex shedding in the wake. A sphere with a diameter of 25.4 mm having a 6 mm circular uniaxial through-hole was fixed to the test section of the wind tunnel and arranged perpendicularly to the streamwise direction. Results show that the vented sphere stabilizes the vortex shedding. A dominant peak at f=55Hz is observed in the wake of the vented sphere, whereas a convex peak over a wide range of 40<f<70Hz is observed in the wake of the basic sphere. In addition, the Reynolds stress in the wake of the vented sphere takes a constant value, whereas it attenuates as the flow moves toward the downstream direction for the basic sphere. The cause of these differences in the Reynolds stress is explained using the co-spectrum of the streamwise and spanwise velocity fluctuations. In the wake of the basic sphere, the negative co-spectrum peak over a wide range of 40<f<70Hz attenuates as the flow moves toward the downstream direction. In contrast, a clear negative peak appears in the wake of the vented sphere at f=55Hz, indicating the persistence of the periodic structure of the vortex shedding as the flow moves toward the downstream direction.

DOI： 10.1016/j.powtec.2022.118175

Calculation model for water mass entrained by the water exit of a particle using two projected images captured from orthogonal directions

Takamure, K; Uchiyama, T

OCEAN ENGINEERING 266 巻 2022年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Ocean Engineering

Water exit is an extremely important phenomenon because it contributes to the development of physics and biology and its application in engineering. In particular, it is necessary to consider the spatiotemporal change in the water mass entrained around an object to correctly understand the scenario of water mass. In this study, a solid particle is launched vertically upward in water toward the surface. The volume of the water mass is estimated using images captured from two orthogonal directions while considering the spatiotemporal development of the water mass. In this study, two water mass estimation methods (Models 1 and 2) are constructed and applied to experimental results of the water exit reported in a previous study by the authors Takamure and Uchiyama (2020a). Model 1 considers the spatiotemporal development of the water mass and estimates the vertical motion of the particle under the influence of water mass with high accuracy when the water mass barely develops around the particle (i.e., submergence depth is small). However, when a large water mass entrains around the particle with an increase in the submergence depth, the estimation accuracy of the volume of the water mass decreases owing to the multilayer structure of the water mass. Model 2 improves the estimation accuracy of the volume of the water mass when the particle covers a large amount of water mass by considering the existence of the multilayer structure of the water mass. For the largest submergence depth in the experiment in this study on the water exit of the particle, the estimation accuracy of the volume of the water mass for Model 1 was approximately 50%, while that for Model 2 was over 80%. Further, the motion of the particle can be estimated with high accuracy even if the water mass is relatively complex and has a multilayer structure by incorporating the effects of the multilayer structure of the water mass into Model 1. This method enables us to estimate the water mass quantity easily and accurately by photographing an object from two orthogonal directions using two synchronized high-speed cameras. This water mass estimation technique is useful for understanding physical phenomena and for engineering applications.

DOI： 10.1016/j.oceaneng.2022.112848

Characteristics of collection and inactivation of virus in air flowing inside a winding conduit equipped with 280 nm deep UV-LEDs

Takamure, K; Sakamoto, Y; Iwatani, Y; Amano, H; Yagi, T; Uchiyama, T

ENVIRONMENT INTERNATIONAL 170 巻 2022年12月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Environment International

A general-purpose virus inactivation unit that can inactivate viruses was developed using deep ultraviolet (DUV) LEDs that emit DUV rays with a wavelength of 280 nm. The inside of the virus inactivation unit is a rectangular conduit with a sharp turn of 180° (sharp-turned rectangular conduit). Virus inactivation is attempted by directly irradiating the air passing through the conduit with DUV rays. The flow characteristics of air and virus particles inside the virus inactivation unit were investigated using numerical simulations. The air was locally accelerated at the sharp turn parts and flowed along the partition plate in the sharp-turned rectangular conduit. The aerosol particles moving in the sharp-turned rectangular conduit were greatly bent in orbit at the sharp turn parts, and then rapidly approached the partition plate at the lower part of the conduit. Consequently, many particles collided with the partition plates behind the sharp-turn parts. SARS-CoV-2 virus was nebulized in the virus inactivation unit, and the RNA concentration and virus inactivation rate with and without the emission of DUV-LEDs were measured in the experiment. The concentration of SARS-CoV-2 RNA was reduced to 60% through DUV-LED irradiation. In addition, SARS-CoV-2 passing through the virus inactivation unit was inactivated below the detection limit by the emission of DUV-LEDs. The virus inactivation rate and the value of the detection limit corresponded to 99.38% and 35.36 TCID50/mL, respectively.

DOI： 10.1016/j.envint.2022.107580

Development of an undershot cross-flow hydraulic turbine resistant to snow and ice masses flowing in an installation canal

Satou, E; Ikeda, T; Uchiyama, T; Okayama, T; Miyazawa, T; Takamure, K; Tsunashima, D

RENEWABLE ENERGY 200 巻頁： 146 - 153 2022年11月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Renewable Energy

This study developed a microhydraulic turbine that can stably and efficiently generate electricity even in canals where snow and ice masses frequently flow down. An undershot cross-flow hydraulic turbine was selected as the development target, and experiments were conducted in an irrigation canal in a heavy snowfall area. Spherical snowballs were made to flow down to the turbine from the upstream direction. The behavior of the snowballs and the power generation performance were investigated as these snowballs passed through the rotor. When the diameter of the snowball is smaller than the blade interval of the rotor, the snowball passing through the rotor causes a small decrease in power output. In contrast, when the diameter of the snowball is larger than the blade interval, the snowball is entrained between the rotor and canal bottom, temporarily stopping the rotor, and resulting in a large decrease in power generation. These results suggest that an undershot cross-flow hydraulic turbine can reduce power generation performance due to snow and ice masses when its blade interval is larger than the expected size of the snow and ice masses. This study developed some design guidelines for this turbine that are highly adaptable to snow- and ice-flowing irrigation canals.

DOI： 10.1016/j.renene.2022.09.062

Characteristics of vortex shedding in the wake of a sphere with a uniaxial through-hole

Kato Hayato, Takamure Kotaro, Uchiyama Tomomi

AIP ADVANCES 12 巻 ( 10 ) 2022年10月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AIP Advances

Wake flows have significant effects on vehicles, buildings, and other objects encountered in daily life. Thus, wake control techniques are of practical importance and have been extensively investigated. One passive wake-control technique is to create a vent on a bluff body, which has been determined to be effective for wake control on a circular cylinder but has not been sufficiently studied for wake control on a sphere. Therefore, this study examined the effect of the vent angle on the characteristics of the wake of a sphere. A sphere with a uniaxial through-hole (vent) was placed in a uniform flow, and the vent angle was varied in the streamwise direction. The Strouhal number in the high-frequency and low-frequency modes was examined. The flow field in the sphere wake varied with respect to the vent angle. Three frequency modes (high, low, and very low), the occurrence of a switching phenomenon, wherein the velocity fluctuated between positive and negative values, and high-frequency energy injection by the vent were observed. In addition, a high dominant frequency was observed only in the positive velocity fluctuation region.

DOI： 10.1063/5.0098762

Effect of cone on efficiency improvement of a self-powered IoT-based hydro turbine

Takamure, K; Uchiyama, T; Horie, K; Nakayama, H

ADVANCES IN MECHANICAL ENGINEERING 14 巻 ( 7 ) 2022年7月

Blocking effect of desktop air curtain on aerosols in exhaled breath

Takamure, K; Sakamoto, Y; Yagi, T; Iwatani, Y; Amano, H; Uchiyama, T

AIP ADVANCES 12 巻 ( 5 ) 2022年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：AIP Advances

A desktop-type air curtain system (DACS) capable of being installed on a desk to protect healthcare workers from infectious diseases was developed. Pseudo-exhaled air containing aerosol particles emitted from a mannequin was blown toward the air curtain generated by the DACS. The aerosol blocking effect of the DACS was investigated using particle image velocimetry measurements. A scenario in which the arm of a patient in the blood collection room is placed on the gate of the DACS was also investigated. Air curtain flow was maintained inside the gate of the DACS. The aerosol particles approaching the DACS were observed to bend abruptly toward the suction port without passing through the gate, signifying that the aerosol particles were blocked by the air curtain flow. When the arm of the patient was placed on the gate of the DACS during blood collection, the airflow above the arm was disrupted. However, the aerosol blocking performance remained unaffected. We envisage that this system will be useful as an indirect barrier not only in the medical field but also in situations where sufficient physical distance cannot be maintained, such as at the reception counter.

DOI： 10.1063/5.0086659

Numerical analysis of effect of Reynolds number on interaction of density-stratified fluid with a vortex ring

Cao, LL; Takamure, K; Uchiyama, T

PHYSICS OF FLUIDS 34 巻 ( 5 ) 2022年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physics of Fluids

In this study, the effect of Reynolds number (Re) on the mixing process of a two-layer density-stratified fluid, caused by the interaction between a vortex ring and the density interface, was numerically investigated using an improved vortex-in-cell method. The density-stratified fluid consisted of water (upper layer) and an aqueous sodium chloride solution (lower layer). Re of the simulated vortex ring was varied from 644 to 1932. We numerically investigated the behavior of the vortex ring and density-stratified fluid, and compared the same with that from a previously conducted experimental study from the literature. The vortex structure generated during the interaction was visualized in three dimensions. Furthermore, the mixing process was evaluated in terms of the stirring index, gradient of concentration, and stirring efficiency. The mixing behavior of the vortex ring was a function of the interaction pattern. For example, for a large Re, with the penetrative pattern, the stirring efficiency reached a constant value that was smaller than that from the partially penetrative pattern. The results showed that a strong stirring caused by an increase in Re of the vortex ring would not always lead to effective mixing.

DOI： 10.1063/5.0086096