研究者詳細 - 坪井　伸幸

論文 - 坪井　伸幸

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Numerical Analysis on Ammonia / Hydrogen / Air Detonation Using Detailed Chemical Reaction Model 査読有り国際誌

G. Inoue, N. Tsuboi, K. Ozawa, A.K. Hayashi

28th International Colloquium on the Dynamics of Explosions and Reactive systems Paper 94 2022年06月

Operation Characteristics of a Disk-Type Rotating Detonation Engine 査読有り国際誌

K. Ishii, K. Ohno, H. Kawana, K. Kawasaki, A.K. Hayashi, N. Tsuboi

28th International Colloquium on the Dynamics of Explosions and Reactive systems Paper 203 2022年06月

Numerical Analysis on Pressure Gain of Rotating Detonation Engine Using H2-O2 Gases: Influence of Number of Injector 査読有り国際誌

A.K. Hayashi, K. Yoshidomi, K. Ozawa, N. Tsuboi, H. Kawashima

28th International Colloquium on the Dynamics of Explosions and Reactive systems Paper 218 2022年06月

Experimental and Numerical Study on Disc-RDE: Relation between Number of Detonation Wave and Pressure 査読有り国際誌

Koichi Hayashi A., Ohno K., Ishii K., Shimomura K., Tsuboi N., Ozawa K., Jourdaine N.H., Dzieminska E., Obara T., Maeda S., Mizukaki T.

AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2022 2022年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Disc-RDE is studied experimentally and numerically to figure out how single-wave mode and double-wave mode appear. From the measurement, we can pick up the better condition for the better pressure gain result. The experimental results are obtained that rotating detonation waves mainly propagate near the outer circumference of the combustion chamber. A transition of the wave number from single to double is found to exist at the equivalence ratio of 0.67 to 0.84. However, the normal transition of wave number is from double to single transition at the equivalence ratio of 1.45 and higher. Numerical work starts with a single-wave system to turn to double-wave system, then single-wave system back due to the ignition, bifurcation, and so on. Depending on the condition, a single-wave becomes a double-wave, which is confirmed at both the experiment and numerical analysis. The reduction of detonation velocity is confirmed at both experiment and numerical calculation up to 7 % when a single detonation becomes double one.

DOI： 10.2514/6.2022-0837

Scopus

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Numerical Simulation on Rotating Detonation Engine: Effect of Number of Injection Ports in Non-Premixed H2-O2 Gases 査読有り国際誌

Yoshidomi K., Kurita N., Ozawa K., Tsuboi N., Hayashi A.K., Kawashima H.

AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2022 2022年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The effect of the number of injection ports in H2-O2 non-premixed gases on the performance of rotating detonation engine is estimated using two-dimensional numerical simulation with a detailed H2-O2 chemical reaction model. The differences in the instantaneous flow field, specific impulse, detonation velocity, and pressure gain are discussed among three configurations with the different numbers of injection ports. The detonation disappears for the 40-port configuration, while it continues to propagate stably for 60-and 80-port configurations. During the detonation propagation, the specific impulse has small, but significant difference depending on the number of injection ports. Detonation velocity is lower than the CJ velocity and its difference increases as the number of injection ports decreases. Pressure gain using oxygen has a maximum value of-0.084 at the 60-port configuration.

DOI： 10.2514/6.2022-1112

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85123582558&origin=inward

Numerical Simulation of Jet Mixing in Supersonic Crossflow: Effect of Jet Exit Geometry 査読有り国際誌

IWASA Toshihiro, TSUBOI Nobuyuki

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES ( 一般社団法人日本航空宇宙学会 ) 65 ( 4 ) 172 - 184 2022年01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）

<p>Implicit large-eddy simulation/Reynolds-averaged Navier-Stokes hybrid simulation of sheet-like hydrogen jets in a supersonic crossflow are performed to investigate jet mixing, focusing on the difference in flow structures between sheet-like jets and round jets. The simulation is validated with a helium jet experiment in terms of the mean concentration. The numerical results showed good agreement with the experimental results. A characteristic of injection from the sheet-like jet exit is the spread of the windward jet toward the spanwise direction owing to the strong interaction with the freestream, while the leeward jet highly penetrated the freestream. In the investigation on jet mixing using different jet exit geometries, it was found that the sheet-like jet has a lower mixing efficiency compared with the round jet. The two mixing characteristics of the sheet-like jet are (i) a large jet cross-sectional area, and (ii) a weak turbulent mixing in the windward shear layer. As the effect of the momentum flux ratio on the jet mixing with sheet-like jet port, the mixing is enhanced with increasing the momentum flux ratio.</p>

DOI： 10.2322/tjsass.65.172

CiNii Research

Attempts of Time-Resolved Fuel Regression Measurements of an Altering-Swirling-Oxidizer-Flow-Type Hybrid Rocket Motor 査読有り国際誌

Ozawa K., Omiya K., Tsuboi N., Ishii K.

AIAA AVIATION 2022 Forum 2022年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

This paper presents efforts to acquire the time-resolved fuel regression data of an Altering-Swirling-Oxidizer-Flow-Type (A-SOFT) hybrid rocket motor using polylactic acid (PLA)-based segmented solid fuels as well as the steady-state fuel regression behavior of the A-SOFT with PLA-based solid fuel. The sensing segments are manufactured by the multi-material Fused Filament Fabrication. They have a ladder-shaped resistor structure to detect the fuel regression in the form of rapid voltage changes caused by its rung destruction. Despite the successful firings of the motor, the verification of the temporally resolved fuel regression was imperfect. The destructions of the first and final rungs provided rapid voltage change, but the other rungs did not provide a rapid voltage change when they were expected to be broken according to the time-averaged regression rate of the segment. The major factors causing the unexpected sensor voltages can include chamber pressure and thermal environments in the motor because the sensor structure had not been tested under these conditions. The spatiotemporal-averaged fuel regression behavior was approximated by a fuel-mass-flux-based linear regression, reflecting the variety of filling rates in additive-manufactured solid fuels. The approximation agreed with the resultant fuel regression behavior, with the residual standard deviation of 2.97×10-2 mm/s. The segmentation of the solid fuels provided the ease of post-experimental measurements of axial distribution of regression rates.

DOI： 10.2514/6.2022-3565

Scopus

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Numerical Simulation of the Deflagration to Detonation Transition in a Tube with Repeated Obstacles: Experimental Scale Simulation Using the Artificial Thickened Flame Method 査読有り国際誌

N. Tsuboi, A.K. Hayashi, Y. Tamauchi, T. Kodama

Transactions on Aerospace Research 4 ( 265 ) 41 - 53 2021年12月

Numerical investigation of three deflagration-to-detonation transition conditions related to the velocity of the spontaneous reaction wave 査読有り

Tang X., Dziemińska E., Hayashi A.K., Tsuboi N.

International Journal of Hydrogen Energy 46 ( 75 ) 37487 - 37501 2021年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

In this work, the deflagration-to-detonation transition (DDT) process in a tube filled with quiescent and stoichiometric hydrogen/oxygen mixture is numerically simulated by a detailed chemical reaction model together with a high-resolution adaptive mesh refinement (AMR) mesh system. Then the flow field is analyzed in detail. It is found that for the onset of detonation in a DDT process there are three essential conditions related to the velocity of the spontaneous reaction wave DSpRW. The first condition is that on a hot spot the DSpRW should be slower than the speed of the Chapman–Jouguet (CJ) detonation wave DCJ to make sure that a spontaneous shock wave could arise originating from the spontaneous reaction wave. The spontaneous shock wave and the spontaneous reaction wave have conspicuous positive correlation to accelerate the spontaneous reaction wave to be faster than the local sound speed, which is the second DDT condition. With this condition the spontaneous reaction wave could catch up with its associated spontaneous shock wave and implement a coupling of the gasdynamics and the chemical energy release. This process is in line with Lee's SWACER idea, while throughout the process the spontaneous reaction wave propagates mainly through the Zel'dovich's reactivity gradients mechanism. Meanwhile, the gas velocity Vg is also essential to maintain the above two conditions and the resultant velocity meets the relation ∥DSpRW+Vg∥≥DCJ, which is the third condition. Distinctly this settles the wave speed gap between deflagration and detonation. More importantly, gas velocity plays an important role especially for the pressure build-up. The most important expressive differences between CJ deflagration and CJ detonation are the gas velocities of both the reactants and products as well as the pressure build-up. When these three relations successfully trigger a DDT and get a detonation wave, they still hold in the resulting detonation wave. They are delicately inherited as the inherent characters of the (detonation) wave. Formerly they are preconditioning-sustaining in the DDT process, and now they become self-sustaining in the detonation wave. Besides, the important role of the progress ratio of the induction period ε is emphasized for a spontaneous propagation.

DOI： 10.1016/j.ijhydene.2021.09.055

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85116006904&origin=inward

Time-resolved fuel regression measurement function of a hybrid rocket solid fuel integrated by multi-material additive manufacturing 査読有り

Ozawa K., Wang H.w., Yoshino T., Tsuboi N.

Acta Astronautica 187 89 - 100 2021年10月

記述言語：英語掲載種別：研究論文（学術雑誌）

The function of time-resolved fuel regression measurement is integrated into additively manufactured hybrid rocket fuels and conceptually demonstrated through the comparison with time-resolved optical fuel regression measurements during burns. This function is enabled by multi-material additive manufacturing of mainly thermoplastic solid fuels with a ladder-shaped resistor made of a conductive thermoplastic. This functionalization has many advantages, as indicated by its wide range of applicability, including solid fuel grains with emerging complex geometries, cost-effectiveness, ease of implementation, and minimal influence on the original propulsive performance and fuel regression behavior. Fuel regression is detected by a step change in the voltage applied to the ladder-shaped resistor, indicating the breakage of its top fuel surface rung during a burn. For ignited cases, all the rung breaks were detected, while the fuel regression was also optically measured using high-speed video. Errors were observed between the fuel regression time-histories measured using the two methods; however, most of these errors could be explained by the distribution of the fuel regression in the camera direction and the camera resolution and the melted fuel layer thickness. Considering these uncertainties, the remaining errors that could not be explained by these factors were less than ±0.15 mm, corresponding to ±1 layer of additive manufacturing applied to the prototyping of the solid fuels.

DOI： 10.1016/j.actaastro.2021.06.031

Scopus

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Experimental and numerical study on disc-rde: Flow structure and its performances 査読有り

Hayashi A.K., Ishii K., Watanabe T., Tsuboi N., Ozawa K., Jourdaine N.H., Dzieminska E., Tang X., Obara T., Maeda S., Mizukaki T.

AIAA Scitech 2021 Forum 1 PartF 1 - 12 2021年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

The present study discusses disc-type rotating detonation engine (DRDE) experimentally and numerically. The experimental work shows that the detonation propagates in three different modes; single, dual, and hybrid. The operating frequency of dual-wave mode is 1.8-2.1 times faster than that of single wave mode. The number of detonation wave can be predicted based on the pressure history and the operating frequency signal. The numerical work shows the performance of 3D numerical analysis of DRDE with uniform injection case and multiport injection case. By increasing the wave number from one to two, the detonation propagation velocity decreases by 18.7 %. The one-detonation head case gives some better performance to the flow than the two-detonation head case. The inlet flow angle to the radial turbine becomes about 50 degrees to the radial direction no matter how large the plenum chamber is.

Scopus

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ワックス燃料後退速度の加速度環境下における可視化システム研究開発

長坂春花, 小澤晃平, 坪井伸幸, 中田大将

日本機械学会九州支部講演論文集 ( 一般社団法人日本機械学会 ) 2021 ( 0 ) 2021年01月

Regression behavior of polylactic acid manufactured by fused filament fabrication for hybrid rocket propulsion 査読有り国際誌

Ozawa Kohei, Wang Han-wei, Inenaga Takefumi, Tsuboi Nobuyuki

Science and Technology of Energetic Materials ( 一般社団法人火薬学会 ) 82 ( 6 ) 170 - 177 2021年01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）

Advanced closed-loop control of thrust and mixture ratio of hybrid rockets is planned by combing a fuel mass flow rate control technique with a real-time fuel regression measurement. The latter technique is enabled by a multi-materialadditive-manufactured solid fuel with an integrated sensor probe structure. This work investigated the fuel regression behavior of polylactic acid (PLA) fuel used for the main material of this type of solid fuels. Rectangular slab fuels and cylindrical fuel grains were manufactured by Fused Filament Fabrication (FFF) and fired in an optically accessible slab burner and a lab-scale motor, respectively. The cylindrical fuel grains had more than 2 times larger regression rates than rectangular slab fuels even with the same PLA filament. One of the main factors causing this large difference can be an anisotropy in the fuel regression rate behavior of the solid fuels manufactured by FFF.

DOI： 10.34571/stem.82.6_170

CiNii Article

CiNii Research

その他リンク： http://hdl.handle.net/10228/00008705

3D numerical study on flow field in disc-RDE 査読有り国際誌

Hayashi A.K., Shimomura K., Tsuboi N., Ozawa K., Jourdaine N.H., Ishii K., Dzieminska E., Obara T., Maeda S., Mizukaki T.

AIAA Propulsion and Energy Forum, 2021 2021年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Disc-type rotating detonation engine is studied numerically using the threedimensional compressible Navier-Stokes equations with 9 species and 21 reactions and with an multi-port injection system. Especially the grid resolution using two-detonation case and the process of stabilization for one and two-detonation cases are studied. As the results of grid resolution, the case of larger grid number provides higher pressure due to capturing the pressure oscilation better and that their rotating speed becomes faster. And the detonation velocity becomes faster when the number of grid becomes larger. As the results of the process of stabilization for one and two-detonation cases, two detonation wave propagate by changing back and forth their distance and no matter what the number of detonation wave is given, one or two, the final detonation wave number becomes two.

DOI： 10.2514/6.2021-3665

Scopus

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Numerical simulations on propane/oxygen detonation in a narrow channel using a detailed chemical mechanism: formation and detailed structure of irregular cells 査読有り国際誌

Takeshima N., Ozawa K., Tsuboi N., Hayashi A.K., Morii Y.

Shock Waves 30 ( 7-8 ) 809 - 824 2020年11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）

Numerical simulations of two-dimensional inviscid detonations for a stoichiometric propane/oxygen gas mixture are performed using a detailed chemical reaction model. The UC San Diego model which includes 57 chemical species and 268 elementary reactions is mainly used in the present study. It is shown that a grid size of 3 µm can capture important features such as the unburned gas pocket behind the detonation when compared to larger grid sizes. The effects of channel width show that the detonation propagates with the CJ (Chapman–Jouguet) velocity for all cases and for more than 100 times the channel width of 4.5 mm. Increasing the channel width results in an irregular detonation cell structure. A transverse detonation forms with cross-hatching marks on the maximum pressure history. The irregular detonation cell structure forms because both the reduced activation energy and the stability parameter have a value of approximately 10; however, the maximum thermicity in the detonation is one. The free radicals C3H7 and H2O2 play an important role in the propane oxidation under the high temperature in the detonation. The maximum concentration exists at a temperature of 2000–3000 K. The fifth-order WCNS (weighted compact nonlinear scheme) scheme can resolve the contact surface and complicated flow structure behind the detonation front compared to the second-order MUSCL (Monotonic Upstream-centered Scheme for Conservation Laws).

DOI： 10.1007/s00193-020-00978-5

Scopus

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Recent Experimental and Numerical Study on Disc-Type RDEs 査読有り国際誌

A. K. Hayashi, N. Tsuboi, K. Ozawa, T. Watanabe, N.H. Jordaine, K. Ishii, H. Kawana, W. Kuwata, K. Ohno, T. Obara, S. Maeda, E. Dzieminska, X. Tang, T. Mizukaki

2020 AIAA SciTech AIAA-2020-1169 2020年01月

Numerical Simulation on Disk Rotating Detonation Engine: Influence of Internal Flow Field Structure on Performance 査読有り国際誌

Tomohiro Watanabe, Kodai Shimomura, Nicolas H. Jourdaine, Kohei Ozawa, Nobuyuki Tsuboi, Takayuki Kojima, Kazuhiro Ishii, A. Koichi Hayashi

AIAA Scitech 2020 Forum AIAA-2020-2160 2020年01月

Three-Dimensional Numerical Simulation on Hydrogen/Air Rotating Detonation Engine with Aerospike Nozzle: Effects of Nozzle Geometries 査読有り国際誌

Nobuhiro Kurita, Nicolas Jourdaine, Nobuyuki Tsuboi, Kohei Ozawa, A. Koichi Hayashi

2020 AIAA SciTech AIAA-2020-0688 2020年01月

多素材3Dプリンタ製燃料後退計測機能付き固体燃料の研究

小澤晃平, 王瀚緯, 坪井伸幸

スペース・エンジニアリング・コンファレンス講演論文集 ( 一般社団法人日本機械学会 ) 2020 ( 0 ) 2020年01月

記述言語：英語掲載種別：研究論文（研究会，シンポジウム資料等）

<p>Prototype solid fuels for a hybrid rocket were fabricated by using a multi-material 3D printer and conductive thermoplastic composite to construct a ladder-shaped resistance inside the electrically-insulated thermoplastic solid fuel and to measure the time-resolved fuel regression. In this type of fuels, the remaining fuel thickness is monitored by the voltage applied to the resistance that changes according to the number of rungs of the ladder-shaped resistor. For comparison with the proposed measurement, the time-resolved fuel regression was optically measured by using a high-speed video visualization. The solid fuel regression history with the proposed technique agreed well with that with the optical measurement considering the uncertainties in the measurement methods. Errors that cannot be explained by these uncertainties were found to be ±0.15 [mm], corresponding to ±1 layer of the stacking pitch of the 3D printer applied in this study. This paper also shows a preliminary firing test result using a post-processed 3D-printed cylindrical solid fuel grain as a preparation for the application of the proposed technique to the cylindrical solid fuel.</p>

DOI： 10.1299/jsmesec.2020.29.C1

CiNii Article

その他リンク： https://ci.nii.ac.jp/naid/130008064623

Three-dimensional numerical simulation on hydrogen/air rotating detonation engine with aerospike nozzle: Effects of nozzle geometries 査読有り

Kurita N., Jourdaine N., Tsuboi N., Ozawa K., Hayashi A.K., Kojima T.

AIAA Scitech 2020 Forum 1 PartF 2020年01月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）

Three-dimensional simulations with a detailed chemical reaction model were performed to evaluate the propulsive performance of rotating detonation engines (RDEs) for H2/Air with conic aerospike nozzles. The simulations aimed to clarify the propulsive performance for various configurations of aerospike nozzle: open/choked or complete/truncated configurations. The governing equations were the Euler equations, and the chemical model was for 9 species and 21 element chemical reactions. Various equivalent ratios from 0.9 to 1.4 were simulated. The results show that the specific impulse (Isp) and the efficiency of the choked nozzle were 4-6% higher than those for the open nozzle. The higher pressure in the chamber due to the decreasing in the throat area resulted in a gain of pressure thrust by the nozzle and consequently, an addition in Isp and the efficiency. The difference in thrust performance between the complete and the truncated nozzle was smaller than 2% because the pressure component on the base surface compensated for the thrust drop.

DOI： 10.2514/6.2020-0688

Scopus

その他リンク： https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85091953963&origin=inward

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