研究者詳細 - 杵淵　紀世志

その他リンク： https://link.springer.com/article/10.1007/s44205-025-00110-8/fulltext.html

Visualization of suppressed shock wave/turbulent boundary layer interaction using cryogenic wall cooling 査読有り

Miki Y., Ando L., Acuña M., Kinefuchi K.

Physics of Fluids 37 巻 ( 1 ) 2025年1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

To investigate the wall-cooling effects on shock wave/turbulent boundary layer interaction (SWTBLI) with limited experimental data, a supersonic wind tunnel wall was cooled using liquid nitrogen as the cryogenic coolant. Under the condition of the mainstream Mach number, in the range of 2.02-2.04, the wall temperature was cooled to 88-92 K, corresponding to a wall-to-recovery temperature ratio of 0.31-0.33. The flow structures with and without wall cooling were observed using the schlieren method. The reflected shock motion or interaction length in the schlieren image suggested that boundary layer separation was suppressed under the cooling condition in relation to that under the non-cooling condition, and the suppressed ratio of the cooling-to-uncooling interaction length was approximately 0.60-0.72. Additionally, while the mainstream state and wall temperature near the separation were constant, a gradual change in the separated flow field was observed under the wall-cooling condition. This was due to the slow wall temperature increase in the upstream wall of the separation region, where the incoming boundary layer developed. Each flow field of SWTBLI in the present experiment, using liquid nitrogen as the cryogenic coolant, was consistent with the classical Chaman's free interaction theory.

DOI： 10.1063/5.0250796

Characterization of heated volume generation by nanosecond pulsed plasma actuator with various pressure environments 査読有り

Matsunaga T., Iwamoto M., Miki Y., Kinefuchi K.

Journal of Physics D: Applied Physics 57 巻 ( 37 ) 2024年9月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Physics D: Applied Physics

Nanosecond dielectric barrier discharge (NS-DBD) has emerged as a promising technique for controlling high-speed flows, generating a heated volume that generates strong density and viscosity gradients, thereby perturbing flow dynamics. Since its potential application in low-pressure, high-speed flows, understanding how the size and growth of the heated volume correlate with surrounding pressure is crucial. In this study, we employed typical schlieren and background-oriented schlieren (BOS) techniques to investigate the heated volume’s sensitivity to surrounding pressure in quiescent air. The observed heated volume’s size variations with surrounding pressure likely stemmed from the increase in thermal diffusivity at lower pressures. BOS findings unveiled a nearly linear decrease in heated volume’s core density with energy input. Meanwhile, the heated volume’s size augmented with energy input but exhibited gradual saturation, attributable possibly to shear stresses impeding volume expansion as temperature and viscosity rose, or to consumption of energy in vibration excitation and other reactions. In the cases of 100 and 50 kPa, the sensitivity of the heated volume’s size to the reduced electric field appeared to be similar. However, at 10 kPa, where the reduced electric field is higher compared to that of the 100 and 50 kPa cases due to the lower air density, the size sensitivity drastically decreased. This suggested a transition in discharge mode from filamentary to diffusive behavior at lower pressures.

DOI： 10.1088/1361-6463/ad5699

Onboard Cryogenic Liquid-Propellant Subcooler Based on Thermodynamic Vent for Upper-Stage Propulsion System 査読有り

Banno Y., Kinefuchi K.

Journal of Spacecraft and Rockets 61 巻 ( 4 ) 頁： 919 - 929 2024年7月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Spacecraft and Rockets

Subcooling of cryogenic liquid propellants offers significant advantages for launch vehicles. Liquid subcooling can reduce the extent of cavitation generation in turbopumps, which provides advantages for upper-stage engine reignition in orbit. Additionally, liquid-propellant subcooling densifies the liquid, which can reduce the propellant tank volume and increase launch capability when it is applied during the propellant-filling phase on the ground. Here, a cryogenic propellant subcooling system derived from thermodynamic vent system (TVS) concepts is proposed. In contrast to prior approaches with TVS, the proposed method only focuses on the liquid subcooling and only requires the installation of a heat exchanger at the tank bottom, making it easily applicable to conventional upper stages and enhancing launch capability. First, ground tests were conducted using liquid nitrogen. We introduced energy efficiency to evaluate the subcooler performance, and an optimum point was found for the coolant supply pressure and Joule–Thomson orifice diameter. To investigate the advantages of the proposed method, a theoretical model for the subcooling process before engine reignition in orbit was developed based on experimental observation. The model assuming liquid hydrogen demonstrated an improved weight penalty in the proposed method compared to the conventional vent/pressurization method. A study that quantitatively addresses the enhancement of launch capability through TVS-induced liquid subcooling is unprecedented, paving the way for a new cryogenic propulsion system.

DOI： 10.2514/1.A35888

Background-oriented schlieren and laser Rayleigh scattering complementary method for accurate density field visualization 査読有り

Iwamoto M., Miki Y., Kinefuchi K.

Experiments in Fluids 65 巻 ( 6 ) 2024年6月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Experiments in Fluids

Gas flow visualization is an essential technique for understanding the gas flow characteristics. Various quantitative distribution measurement methods have been proposed, each with its own advantages and disadvantages. For example, the background-oriented schlieren method provides the quantitative density distribution for wide areas with a simple optical setup, but it disadvantageously requires the appropriate boundary conditions need to be set when integrating the Poisson equation. The laser Rayleigh scattering method also provides quantitative density distribution, but it requires a high-power laser for wide-area measurements because laser intensity directly influences measurement accuracy. This study proposes a method that complements the weak points of the above two methods. First, a wide area is measured using the background-oriented schlieren method, and then, the laser Rayleigh scattering method is applied only for the boundary region to obtain the boundary condition. For a heated turbulent air jet with Reynolds number 3000, the results of the proposed method are compared with the numerical analysis and thermocouple temperature measurements. The results well match, indicating the applicability and usefulness of the proposed method. Furthermore, these results contribute to demonstrating the significance of boundary conditions in the background-oriented schlieren method and the establishment of setting guidelines.

DOI： 10.1007/s00348-024-03772-6

Operational demonstration and experimental characterisation of a central cathode electrostatic thruster equipped with a high temperature superconducting magnet 査読有り

Plume mode instability enhanced by emitter surface poisoning in hollow cathode 査読有り Open Access

Suzuki A., Cho S., Watanabe H., Kinefuchi K.

Journal of Applied Physics 135 巻 ( 10 ) 頁： 103301 2024年3月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Applied Physics

The unstable plume mode of hollow cathodes should be avoided in practical applications because it severely degrades the overall cathode lifetime. In this study, we investigate the spot-plume transition and plasma stability characteristics of an unused segmented lanthanum hexaboride emitter. The expansion of the unstable plume mode region is observed during a discharge experiment. Subsequently, the segmented emitter is retrieved, the inner surface of the emitter is observed, and the work function on the surface is measured at room temperature. The emitter surface exhibits color variations with oxygen and carbon detection. The downstream edge shows the original purple color and almost no degradation in the work function. The high temperature in this region promotes the desorption of carbon and oxygen. In the spot mode, this region mainly contributes to thermionic electron emission; therefore, the discharge voltage in the spot mode does not change during the discharge experiment. Carbon or carbide is detected in the middle of the axial direction on the emitter surface, where the surface temperature is not sufficiently high to desorb carbon during discharge. Based on the surface analysis results, the dominant substance in the region where carbon is detected was lanthanum carbide. An increase in the work function is indicated in the region, which appears to increase the plasma instability. According to previous studies, an increase in the work function results in a rise in the potential in the emitter, and an increase in the electron temperature in the outside plume region induces the plasma instability. Further investigation is needed to understand the mechanism connecting the rise in the work function and the rise in the electron temperature in the plume region.

DOI： 10.1063/5.0188080

Operation of a plasma thruster featuring a 1.1 T high temperature superconducting magnet 査読有り

Chris R. Acheson, Kiyoshi Kinefuchi, Daisuke Ichihara, Daiki Maeshima, Ryoyu Mori, Ryota Nakano, Ryohei Takagi, Konstantinos Bouloukakis, Jakub Glowacki, Max Goddard-Winchester, Nicholas J. Long, Jamal R. Olatunji, Betina Pavri, Randy Pollock, Cameron Shellard, Nick M. Strickland, Stuart C. Wimbush

Journal of Electric Propulsion 3 巻 ( 17 ) 2024年

Performance Evaluation of a Plasma Thruster Using a High-Temperature Superconducting Magnet 査読有り

Kiyoshi Kinefuchi, Stuart Wimbush, Daisuke Ichihara, Chris Acheson, Ryota Nakano, Daiki Maeshima, Ryohei Takagi, Ryoyu Mori, Jamal Olatunji, Max Goddard-Winchester, Randy Pollock, Nick Strickland, Jakub Glowacki, Betina Pavri

Transactions of the JSASS, Aerospace Technology Japan 22 巻 ( AJCPP-2023 ) 頁： aj1 - aj6 2024年

Investigation on the Hybrid NS-DSMC Simulation of a Nozzle Flow Ionization in a Rarefied Atmosphere using a Post-computation Approach 査読有り

Virgile CHARTON, Julien LABAUNE, Kiyoshi KINEFUCHI

Journal of Evolving Space Activities 2 巻 ( 0 ) 頁： 153 2024年

Chris R. Acheson, Jakub Glowacki, Ryota Nakano, Daiki Maeshima, Dominik Saile, Betina Pavri, Ryohei Takagi, Ryoyu Mori, Randy Pollock, Jamal R. Olatunji, Max Goddard-Winchester, Nicholas M. Strickland, Daisuke Ichihara, Stuart C. Wimbush, Kiyoshi Kinefuchi

Journal of Electric Propulsion 2 巻 ( 1 ) 2023年12月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Springer Science and Business Media LLC

Abstract

Interplanetary transport of payloads of unprecedented mass, as envisaged beyond the lunar gateway, will require thrusters with high specific impulse as well as high thrust. To achieve this, innovations in propulsion are critical. Many classes of electric thruster utilise a magnetic applied field module to accelerate charged particles. Magnetoplasmadynamic thrusters exhibit improved performance with increasing field, at least up to the limit of around 0.5 T able to be provided by permanent magnets or copper electromagnets. However, superconducting magnets can generate much stronger magnetic fields. In this study, we utilised a space-relevant cryocooled high temperature superconducting magnet as the applied field module for a central cathode electrostatic thruster (CC-EST). A convex anode enabled ignition at high magnetic fields, and in this configuration the thruster’s performance was characterised in the power range of 1 kW to 2.5 kW and at steady applied fields ranging from 0.6 T to 0.8 T, representing a significant advance in achievable field strength. In combination, these operating parameters enabled the achievement of a magnet-inclusive thruster efficiency of 19%, while the cryocooled magnet was demonstrated to be thermally stable in the presence of the kW-scale plasma, demonstrating the viability of such a design for space flight applications.

DOI： 10.1007/s44205-023-00060-z

その他リンク： https://link.springer.com/article/10.1007/s44205-023-00060-z/fulltext.html

Energetic ion and plasma oscillation measurements during plume mode operation of a hollow cathode 査読有り

Suzuki A., Kinefuchi K., Ichihara D., Cho S., Watanabe H., Kubota K.

Physics of Plasmas 30 巻 ( 7 ) 2023年7月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Physics of Plasmas

Hollow cathodes are important devices used for spacecraft electric propulsion. The hollow cathode has two operational modes. One mode is a stable mode called the spot mode, and the other is an unstable mode called the plume mode. Operation in plume mode should be avoided since the instability causes high-energy ions that sputter-erode the cathode parts. In this study, the relationship between discharge oscillations and ion energy distribution in plume mode was investigated using a triple Langmuir probe and retarding potential analyzer for a 40-A class xenon hollow cathode with a lanthanum hexaboride emitter. The triple probe can measure unsteady electron temperature and plasma density oscillations. The electron temperature was not so high, 1 to 2 eV. Some instabilities were observed in the plume mode. The ionization instability with a low frequency oscillation of 30 kHz was the dominant mode. A broad spectrum around 330 kHz due to ion acoustic turbulence was observed. In addition, in the downstream plume region, oscillations around 120 kHz were observed owing to temporal change in anomalous resistivity. The 95% ion population voltage found to be 20 and 30 eV in spot and plume modes, respectively. The magnitude of the low frequency ionization oscillation was found to be inversely proportional to ion energy in plume mode. This indicates that the resonant energy transfer from the oscillation to the ion energy through Landau damping probably plays an important role in high energy ion generation in plume mode. A clear correlation between discharge current and electron temperature waveforms was found. The larger the electron temperature fluctuation, the stronger the correlation between discharge current and electron temperature, and the larger the phase difference deviation from 180°.

DOI： 10.1063/5.0139089

Low power arcjet thruster using LaB<inf>6</inf> hollow cathode 査読有り

Takahashi T., Kinefuchi K.

Acta Astronautica 206 巻頁： 89 - 99 2023年5月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Acta Astronautica

A 100-W class low power arcjet thruster using a hollow cathode was proposed, with the goal of reducing cathode erosion. The hollow cathode's emitter was lanthanum hexaboride expecting its excellent thermionic emission performance. The experiment used argon as a propellant and compared two different emitter lengths. The estimated emitter temperature was almost the same regardless of the emitter length, however, due to of the efficient heat exchange with the longer arc plasma region, the longer emitter provided better performance with higher discharge voltage. Additionally, the hollow cathode was compared to the conventional rod cathode, and the hollow cathode was found to have some advantages. The specific impulse of the hollow cathodes was higher than that of the rod cathode at low flow rate. The results showed that the hollow cathode is best for high specific power and high specific impulse operation. The unstable transition between low- and high-voltage modes has been observed in the rod cathode, but not in the hollow cathode configurations. Helium was put to the test as a propellant and compared to argon for simulate the future use of hydrogen as a propellant. The thrust efficiency was lower due to the high discharge voltage and significant heat loss, but the specific impulse was higher as expected. No severe recession or erosion of the emitter was observed after the test campaign, but some surface color change was seen which may affect in the long-term operation.

DOI： 10.1016/j.actaastro.2023.02.015

Dry ice propellant for electric propulsion with triple-point storage 査読有り Open Access

Maki T., Kinefuchi K., Cho S., Watanabe H.

Acta Astronautica 202 巻頁： 283 - 291 2023年1月

担当区分：責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Acta Astronautica

Dry ice has been proposed as a propellant for electric propulsion, as its use may facilitate the realization of a low-cost propulsion system compared to that based on a xenon propellant. In addition, dry ice can be obtained from space (e.g., from the atmosphere of Mars) and human exhalation. This study thus conducted experiments with dry ice storage and carbon dioxide gas supply using triple-point storage. With this method, a constant tank pressure and flow rate was achieved without the application of regulators or control valves. However, the triple-point state was unexpectedly halted, even though solid dry ice remained in the tank. An internal visual observation revealed that the solid phase was surrounded by the liquid phase, which prevented the solid phase from melting. Therefore, heat conduction fins were installed in the tank to enhance the melting process, which successfully extended the triple-point duration. The supply system was applied successfully to the operation of a 1 kW Hall thruster. Furthermore, a mathematical model for estimating the phase characteristics in the tank was developed, with an in-orbit operation analyzed based on the experimental results. The heat input to the tank and the mass flow rate or enthalpy to the thruster determined the phase characteristics in the tank, which means that implementing a thermal design that considers the flow rate to the thruster is crucial. The simulation demonstrated that dry ice can be consumed by controlling the three phases in the tank using an electrical heater. A gas phase separator concept consisting of the heat conduction fins and capillary screen mesh was proposed for orbital microgravity operation.

DOI： 10.1016/j.actaastro.2022.10.034

Comparison of vapor cooling characteristics of a triply periodic minimal surface and other channel geometries 査読有り

Fukuzaki, T; Kinefuchi, K; Umemura, Y; Okita, K; Sakai, H

Mechanical Engineering Journal 10 巻 ( 3 ) 頁： 23-00015 - 23-00015 2023年

基幹ロケット高度化推進系の開発査読有り

杵淵紀世志, 更江渉, 小林弘明, 梅村悠, 杉森大造, 藪崎大輔, 藤田猛, 沖田耕一, 西村真二, 石川佳太郎, 北山治, 姫野武洋, 佐藤哲也

日本航空宇宙学会誌 70 巻 ( 7 ) 頁： 145 - 152 2022年7月

記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人日本航空宇宙学会

<p>基幹ロケット高度化はH-IIAロケット第2段を改良することにより国際競争力や打上げの柔軟性向上を狙い，2009年度から概念設計を開始し2011年度に開発へ移行した．推進系に対してはロングコーストおよび再々着火実現のための技術開発が課せられ，2013年度に開発を完了した．第2段の性能は輸送能力に直結するため極限の高性能化が求められるが，微小重力や真空といった軌道上環境により地上検証が困難となる．開発では地上要素試験と解析技術を組み合わせ，重要な要素についてはH-IIAロケット上で衛星分離後の機会を利用した軌道上実験を行うなど日本の独自性を生かし産学官共同で開発を進めた．開発の成果は商用通信衛星の受注に繋がり，2機の地球観測衛星の異なる軌道への同時打上げ，惑星間軌道投入にも適用された．獲得した推進系技術はH3ロケットを始め，将来の月探査や再使用ロケットにも貢献する．</p>

DOI： 10.14822/kjsass.70.7_145

CiNii Research

Cooling system optimization of cryogenic propellant storage on lunar surface 査読有り Open Access

Kinefuchi K., Miyakita T., Umemura Y., Nakajima J., Koga M.

Cryogenics 124 巻 2022年6月

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Cryogenics

A cooling system using a cryocooler and boil-off gas was proposed for cryogenic propellant storage on the lunar surface. The cryogenic tank was covered with an advanced non-interlayer-contact multi-layer-insulation and coolant from the cryocooler and boil-off gas flow in the layers to remove the heat load. The proposed system included optimization factors for fluid tubes location, cryocooler temperature, and flow rate. A simple uniform-temperature thermal model was developed to optimize boil-off rates and system weights, and the results revealed a Pareto front. A three-dimensional model was developed to discuss the effect of temperature nonuniformity. Finally, the proposed concept was compared to other candidates. The results showed that the proposed system offered a well-balanced system in terms of boil-off rate, system mass, and electric power consumption, which drastically reduced the boil-off rate when compared to only multi-layer insulations, which reduced the weight and power consumptions as compared to zero-boil-off systems.

DOI： 10.1016/j.cryogenics.2022.103494

Numerical Study of Effect of Pressurant Gas Species on Thermal Behavior in Cryogenic Tank 査読有り

Kinefuchi K., Umemura Y.

Journal of Spacecraft and Rockets 59 巻 ( 4 ) 頁： 1262 - 1275 2022年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Journal of Spacecraft and Rockets

This study numerically reveals effect of pressurant gas species on thermal behavior in a cryogenic propellant tank for space propulsion systems. The simulation was conducted for a ground experiment using liquid nitrogen in which gaseous helium and the same species as the liquid, gaseous nitrogen, were used as prepressurants. The tank was sealed after prepressurization to observe self-pressurization (pressure rise with evaporation) and thermal stratification (high-temperature liquid near the surface). A higher evaporation rate and a thicker thermal layer were observed for helium prepressurization in the experiment. To clarify the underlying physics, a simulation considering phase change and conjugate heat transfer was developed. The simulated pressure and temperature closely matched the experimental results. Conjugate heat transfer played an important role; that is, the heat flow through the ullage part of the tank skin into the cryogenic liquid was a dominant heat transfer process, causing evaporation to occur mainly at the contact point of the wall and the gas–liquid interface. Afterward, nitrogen vapor rose along the tank wall due to buoyancy under nitrogen prepressurization. However, buoyancy in the ullage is lower under helium prepressurization since light helium stayed in the upper part of the ullage, and a radial vapor flow is produced from the contact point, leading to a higher heat flux from the tank wall to the liquid nitrogen. This mechanism shows that evaporation rate and heat flow into the liquid are higher for helium prepressurization than for nitrogen prepressurization.

DOI： 10.2514/1.A35061