研究者詳細 - 河内　俊憲

Flowfield characteristics of a transverse jet into supersonic flow with pseudo-shock wave 査読

H. Yamauchi, B. Choi, K. Takae, T. Kouchi, G. Masuya

Shock Waves 22 ( 6 ) 533 - 545 2012年11月

記述言語：英語掲載種別：研究論文（学術雑誌）

We performed an experimental investigation of the flowfield of a transverse jet into supersonic flow with a pseudo-shock wave (PSW). In this study, we injected compressed air as the injectant, simulating hydrocarbon fuel. A back pressure control valve generated PSW into Mach 2. 5 supersonic flow and controlled its position. The positions of PSW were set at nondimensional distance from the injector by the duct height (x/H) of -1. 0, -2. 5, and -4. 0. Particle image velocimetry (PIV) gave us the velocity of the flowfield. Mie scattering of oil mist only with the jet was used to measure the spread of the injectant. Furthermore, gas sampling measurements at the exit of the test section were carried out to determine the injectant mole fraction distributions. Gas sampling data qualitatively matched the intensity of Mie scattering. PIV measurements indicated that far-upstream PSW decelerated the flow speed of the main stream and developed the boundary layer on the wall of the test section. The flow speed deceleration at the corner of the test section was remarkable. The PSW produced nonuniformity in the main stream and reduced the momentum flux of the main stream in front of the injector. The blowing ratio, defined as the square root of the momentum flux ratio, of the jet and the main stream considering the effect of the boundary layer thickness was shown to be a useful parameter to explain the jet behavior. © 2012 Springer-Verlag.

DOI： 10.1007/s00193-012-0384-9

Turbulent Characteristics for Jet Injected into Supersonic Flow with Pseudo Shock Wave 査読

Byugil Choi, Koichi Takae, Toshinori Kouchi, Goro Masuya

JOURNAL OF PROPULSION AND POWER 28 ( 5 ) 971 - 981 2012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：AMER INST AERONAUTICS ASTRONAUTICS

The mean and turbulent velocity field of a transverse jet in a supersonic flow with a pseudo shock wave by stereoscopic particle image velocimetry was measured. Both the mainstream and the injectant were unheated air. The pseudo shock wave was generated and controlled by means of a flow plug driven by a stepping motor. To study the influence of the generation and development of the pseudo shock wave, measurements are taken for four different cases of the pseudo shock wave location, including one without a pseudo shock wave. Sequences of up to 750 image pairs for each measurement plane were acquired. From these data, the mean and turbulent characteristics of the flowfield were examined, such as mean velocity and vorticity, turbulence intensities, Reynolds stresses, and turbulence kinetic energy. The mean velocity and vorticity indicate that the pseudo shock wave gradually lowered the flow speed of the mainstream and increased the size of the counter-rotating vortex pair. The pseudo shock wave strongly disturbed the flowfield, inducing complicated three-dimensional distortions. The pseudo shock wave disturbed the flowfields near the walls, and the turbulence kinetic energy in this area was kept at a high level over long streamwise distances. The streamwise fluctuation intensity was about 4 times stronger than that of the vertical and lateral components, and the streamwise velocity components fluctuated even more greatly than the cross-sectional velocity components. The transverse injection moderately affected not only turbulence around the jet, but also the turbulent characteristics caused by the pseudo shock wave. The injection not only produced turbulence around the jet, but also suppressed the velocity fluctuation caused by the pseudo shock wave.

DOI： 10.2514/1.B34371

Flowfield Characteristics of a Hypermixer Interacting with Transverse Injection in Supersonic Flow 査読

Chae-Hyoung Kim, In-Seuck Jeung, Byungil Choi, Toshinori Kouchi, Goro Masuya

AIAA JOURNAL 50 ( 8 ) 1742 - 1753 2012年8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：AMER INST AERONAUTICS ASTRONAUTICS

Nonreacting experiments were conducted at Mach 2 to understand the relationship between a wall-mounted alternating-ramp-wedge-type hypermixer and transverse injection compared with a step mixer. Experimental techniques such as schlieren visualization and stereoscopic particle image velocimetry were employed to study the three-dimensional flowfield with vortex structures induced by the interaction between the mixer and transverse injection. Without injection, the hypermixer creates a region that contains vortical motions. When a transverse jet is injected in the vortical region, flow parameters on mixing performance, such as the penetration height, vorticity, and turbulent stress, are improved. Three turbulent-stress components show relatively distinct distributions, and strong turbulent stresses are observed at the upper side of the jet plume. Turbulent-stress distributions are significantly associated with strain rate, which peaks along the sonic line of the jet plume.

DOI： 10.2514/1.J051588

Mechanism and Control of Combustion-Mode Transition in a Scramjet Engine 査読

Kouchi, Toshinori, Masuya, Goro, Mitani, Tohru, Tomioka, Sadatake

Journal of Propulsion and Power 28 ( 1 ) 106 - 112 2012年1月

Quantification of convection velocity and dominant scale of large-scale structures by high-speed schlieren imaging

Toshinori Kouchi, Goro Masuya

48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 2012 AIAA 2012-4148 2012年

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）出版者・発行元：American Institute of Aeronautics and Astronautics

We proposed a new method to evaluate simultaneously both convective velocity and scale of dominant turbulent structures captured in a high speed framing schlieren movie. We took 90 time-series schlieren images of a transverse jet into a Mach 2 supersonic flow with 1 MHz sampling. We focused on periodical image gradations due to the turbulent structures within the jet and boundary layer. We remapped the image intensities on the structures along their trajectory as a time-space map. The time-space map showed swept stripe patterns. The presence of the stripe patterns indicates stable structures were periodically generated and convected downstream. Slope of the stripes corresponds to the convective velocities of the structures. Cycles in the space- and time-directions of the stripes correspond to the scale and formation cycle of the dominant structure. Two-dimensional Fourier transform efficiently extracted the dominant ones from the time-space map. We demonstrated this newlyproposed method using two-dimensional Fourier transform accurately evaluated the convective velocity and scale of the dominant turbulent structures within the jet and boundary layer. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

DOI： 10.2514/6.2012-4148

Focusing-schlieren visualization in direct-connect dual-mode scramjet

Toshinori Kouchi, Christopher P. Goyne, Robert D. Rockwell, Roger Reynolds, Roland Krauss, James C. McDaniel

18th AIAA/3AF International Space Planes and Hypersonic Systems and Technologies Conference 2012 2012年

掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：American Institute of Aeronautics and Astronautics

Schlieren imaging has high sensitivity for density gradient in a flow field, and easily captures not only shock and expansion waves but also turbulent structures in the flow field. The conventional schlieren imaging, however, cannot capture clearly them in directconnect supersonic combustor tests with long duration, because the severe temperature condition in the combustor locally changes the refractive index of the window glasses for optical access. The conventional schlieren technique is essentially sensitive to the entire region of the light path including the glasses. On the other hand, focusing-schlieren technique has narrow depth of focus. Therefore, the imaging is expected to avoid the thermal distortion of the glasses. In this work, we applied focusing-schlieren imaging to the supersonic combustion tests, and tried to clearly capture the flow features inside a dualmode scramjet. The present system had about ± 5 mm depth of focus, and successfully visualized the flow field in the combustor, though the system sensitivity declined with the tunnel heating up. Combustion drastically changed the flow field inside the combustor, and induced volumetric expansion of fuel jet, resulting in pressure rise. Combustiongenerated pressure rise pushed up the shock train up to the trilling edge of the ramp fuel injector. The system recorded two image pairs by using PIV system. These image pairs yielded the convection velocity of turbulent structures in the combustor. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

DOI： 10.2514/6.2012-5834

Large-eddy /reynolds-averaged navier-stokes simulations of a dual-mode scramjet combustor

Jesse A. Fulton, Jack R. Edwards, Hassan A. Hassan, Robert Rockwell, Christopher Goyne, Jim McDaniel, Chad Smith, Andrew Cutler, Craig Johansen, Paul M. Danehy, Toshinori Kouchi

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition 2012年

掲載種別：研究論文（国際会議プロシーディングス）

Numerical simulations of reacting and non-reacting flows within a scramjet combustor configuration experimentally mapped at the University of Virginia's Scramjet Combustion Facility (operating with Configuration "A") are described in this paper. Reynolds-Averaged Navier-Stokes (RANS) and hybrid Large Eddy Simulation /Reynolds-Averaged Navier-Stokes (LES /RANS) methods are utilized, with the intent of comparing essentially 'blind' predictions with results from non-intrusive flow-field measurement methods including coherent anti-Stokes Raman spectroscopy (CARS), hydroxyl radical planar laser-induced fluorescence (OH-PLIF), stereoscopic particle image velocimetry (SPIV), wavelength modulation spectroscopy (WMS), and focusing Schlieren. NC State's REACTMB solver was used both for RANS and LES /RANS, along with a 9-species, 19-reaction H2-air kinetics mechanism by Jachimowski. Inviscid fluxes were evaluated using Edwards' LDFSS flux-splitting scheme, and the Menter BSL turbulence model was utilized in both full-domain RANS simulations and as the unsteady RANS portion of the LES /RANS closure. Simulations were executed and compared with experiment at two equivalence ratios, pdbl= 0.17 and pdbl= 0.34. Results show that the pdbl = 0.17 flame is hotter near the injector while the pdbl = 0.34 flame is displaced further downstream in the combustor, though it is still anchored to the injector. Reactant mixing was predicted to be much better at the lower equivalence ratio. The LES /RANS model appears to predict lower overall heat release compared to RANS (at least for pdbl = 0.17), and its capability to capture the direct effects of larger turbulent eddies leads to much better predictions of reactant mixing and combustion in the flame stabilization region downstream of the fuel injector. Numerical results from the LES/RANS model also show very good agreement with OH-PLIF and SPIV measurements. An un-damped long-wave oscillation of the pre-combustion shock train, which caused convergence problems in some RANS simulations, was also captured in LES /RANS simulations, which were able to accommodate its effects accurately. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Effect of vent mixer to mixing characteristics in supersonic flow

Chae Hyoung Kim, In Seuck Jeung, Byungil Choi, Toshinori Kouchi, Goro Masuya

28th Congress of the International Council of the Aeronautical Sciences 2012, ICAS 2012 4 2864 - 2872 2012年

掲載種別：研究論文（国際会議プロシーディングス）

A Mach 2 hydrogen - air supersonic combustor model with no diffuser was designed and operated in atmospheric inflow condition. A new supersonic mixer, which was vent slot mixer (VSM), was developed and fabricated to use as the device of the fuel-air mixing. At low enthalpy inflow condition, a plasma jet torch was used as the igniter and the flame-holder. An isolator was located between the nozzle and the combustor. In supersonic combustion, the VSM had an effect to increase the mixing efficiency compared with the step mixer. While the combustion pressure was increased, the combustion mode was changed from unstable supersonic combustion to dual-mode transition. When the unstable flow of shock train affected the combustor inlet, the VSM was showed that the combustion stability was slightly sustained when compared with the case ofthe step mixer.

Large-eddy simulation of pseudo-shock wave in a square duct

S. Lee, J. Watanabe, T. Kouchi, K. Takita, G. Masuya

18th AIAA/3AF International Space Planes and Hypersonic Systems and Technologies Conference 2012 2012年

掲載種別：研究論文（国際会議プロシーディングス）

Large-eddy simulation (LES) of Pseudo-Shock Wave (PSW) in a square duct was perfomed to study the three-dimensional turbulent structure. A flow with the PSW in the square section duct produced by the high back pressure was reproduced using LES. The inflow Mach number was 2.5 and the inflow boundary layer of 4.2mm thick. The incoming boundary layer for a square duct was established using the multi rescaling method. The Mach number distribution, schlieren image, wall pressure, and velocity data obtained from the LES were compared with the past experimental data. The shock train structure observed in the experiment was well reproduced by the LES. The averaged wall pressure and streamwise velocity distributions agreed well between the LES and the experiments. Also, the distributions of intensity and spatial correlation of velocity fluctuation reasonably agreed between the LES and the experiment, although some differences were observed in the velocity fluctuation intensity distribution at the position of front shock wave. © 2012 by the American Institute of Aeronautics and Astronautics, Inc.

Velocity field in secondary combustor of ejector-jet

Kiyoshi Nojima, Toshinori Kouchi, Goro Masuya, Sadatake Tomioka

18th AIAA/3AF International Space Planes and Hypersonic Systems and Technologies Conference 2012 ( 2012-5838 ) 2012年

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）出版者・発行元：American Institute of Aeronautics and Astronautics

Three-component velocity distributions in a rocket-ramjet combined cycle engine model operating under a sea-level static condition were measured with a stereoscopic particle image velocimetry. The engine model had two rocket nozzles on top wall side of a flow-path and fuel injectors for the secondary combustion. The rocket exhaust was simulated by the cold compressed air injected at operation condition of 2.4 MPa in chamber pressure. The secondary fuel was simulated by the helium gas. The pressure rise due to combustion was simulated by contracting the exit area of flow path by using a flow plug. The separation region appeared in the cowl side in the ensemble-averaged velocity distribution in the case of combustion simulation. The flow around the separation region was strongly disturbed. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

DOI： 10.2514/6.2012-5838

Turbulent Structure of Supersonic Flowfield 査読

Shohei Uramoto, Toshinori Kouchi, Goro Masuya

Journal of Fluid Science and Technology 7 ( 2 ) 231 - 241 2012年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：The Japan Society of Mechanical Engineers

We investigated a supersonic flowfield with transverse injection of air or helium by stereoscopic particle image velocimetry and calculated single-time two-point spatial correlations of velocity fluctuations. For both injection gases, the bow shock wave formed by the injection and its reflection from the upper wall could be seen in the mean velocity distribution. In the velocity fluctuation intensity distribution, we observed vibrating counter-rotating vortex pair and the Reynolds stress was formed along the track of the maximum mean velocity gradient. Correlations showed the scale structure of turbulence and the shapes of the correlation region changed with the selected velocity component. Differences were observed between the results obtained for the two injectant species.

DOI： 10.1299/jfst.7.231

CiNii Article

Quasi-one dimensional modeling on vitiation effects for a dual-mode combustor

Junji Noda, Masaki Ohkoshi, Toshinori Kouchi, Goro Masuya, Sadatake Tomioka, Robert D. Rockwell, Christopher P. Goyne

18th AIAA/3AF International Space Planes and Hypersonic Systems and Technologies Conference 2012 ( 2012-5862 ) 2012年

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）出版者・発行元：American Institute of Aeronautics and Astronautics

A three-flow-tube, quasi-one dimentional calculation was carried out to estimate modetransition fuel equivalence ratios under clean and vitiated inflow conditions. A simple flame holding model was used in the calculation. In cases of vitiated inflows, both total temperature and total enthalpy matched conditions to that of clean air were tested. Calculated wall pressure distributions were well matched to those of experimental values, qualitatively. Additionally, the ratio of mode-transition equivalence ratio of clean inflow divided by that of vitiated inflow was well matched to that of experimental value. Matched total enthalpy was effective to eliminate the inflow vitiation effects on mode-transition equivalence ratios in a case that thermal choking was attained at constant area exit. However, in a case that thermal choking was attained in the diverging region, matched total enthalpy was not effective. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

DOI： 10.2514/6.2012-5862

Characteristic Study on Effect of the Vent Mixer to Supersonic Fuel-Air Mixing with Stereoscopic-PIV Method

Kim, Chae-Hyoung, SEUCK, JEUNG IN, Kouchi, Toshinori, Masuya, Goro

2012年

Turbulence Induced by Transverse Injection and Pseudo-Shock Wave in Supersonic Flow

Goro Masuya, Byung-Il Choi, Koichi Takae, Toshinori Kouchi

20th International Symposium on Air Breathing Engines ( ISABE Paper 2011-1525 ) 2011年9月

Numerical Study on the Turbulent Structure of Transverse Jet into Supersonic Flow 査読

Junya Watanabe, Toshinori Kouchi, Kenichi Takita, Goro Masuya

AIAA JOURNAL 49 ( 9 ) 2057 - 2067 2011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：AMER INST AERONAUT ASTRONAUT

The three-dimensional turbulent structure and mixing state of a transverse air jet injected into a Mach 1.9 supersonic crossflow were investigated using a large-eddy simulation. Both a grid sensitivity study and detailed comparisons with acetone planar laser-induced fluorescence data were conducted. The large-eddy simulation results well reproduced both the distribution of averaged injectant concentration and the large-scale turbulent features in the windward region of the jet plume. Large-scale vortices on the windward side of the jet plume caused large protrusions of injectant and were the main cause of the turbulent diffusion of injectant toward the crossflow in the near field. The windward large-scale vortex structure consisted of a string of hairpinlike vortices meandering along the jet trajectory. The head of these hairpin vortices tilted toward the upstream and upward directions. The instantaneous combustible injectant mass flux was evaluated by assuming the injectant air to be ethylene. A large amount of combustible injectant existed inside the large-scale protrusions induced by the windward large-scale vortex structure. The combustible injectant mass flow rate passing through the cross section bad substantial fluctuations over time, mainly due to the intermittent appearance of the windward large-scale vortices.

DOI： 10.2514/1.J051067