JAXA Supercomputer System Annual Report April 2019-March 2020

Report Number: R19EG3205

Subject Category: Research and Development

PDF available here

• Responsible Representative: Kouichi Okita, Director, Research Unit IV, Research and Development Directorate
• Contact Information: Masatoshi Kodera(kodera.masatoshi@jaxa.jp)
• Members: Masahiro Takahashi, Masatoshi Kodera, Masaaki Fukui, Toshihiko Munakata, Masaharu Takahashi, Sadatake Tomioka, Takuya Arakawa, Hironobu Nishiguchi, Ko Kurihara, Kazunari Hayashi, Hidemi Takahashi

Abstract

Reusable rockets have been being studied to reduce the cost of space transportation systems significantly in recent years. However, in order to extend the structural lifetime, it is necessary to operate them with relatively low engine power, leading to a decrease in launch capability. Therefore, air-breathing engines such as scramjets and rocket/scram combined cycle engines are promising to compensate the drawback. By using oxygen in the atmosphere as an oxidizer, it becomes highly efficient, and it can be expected to maintain and improve the launch capability even if it is reused. In this project, we will research and develop key technology for practical application of the engine.

Reference URL

N/A

Reasons and benefits of using JAXA Supercomputer System

The following points are raised as problems of engine design by ground experiments. 1) There are limits to reproducing various airflow conditions from takeoff to hypervelocity range. 2) Measured data is limited and complicated three-dimensional flow structure inside the engine can not be well identified. 3) Since the time and cost are limited, it is not easy to change the engine flow path configuration. Therefore, it is indispensable to utilize 3D CFD as a design tool, and a supercomputer is required for performing numerous CFD works efficiently.

Achievements of the Year

(1) 3D RANS CFD was conducted for a supersonic combustor with a cavity fueled by a methane/ethylene mixed fuel, and sensitivity analyses on boundary conditions and physical models were performed and the effect of the mixture ratio for the fuel was examined.

(2) In order to verify the prediction accuracy of a simple reaction mechanism for ethylene/air combustion, 2D CFD was performed for supersonic combustor flows and the results were compared with the ones using a detailed mechanism.

(3) Numerical analyses on non-reacting flows in a scramjet combustor were carried out using hybrid LES/RANS. It was observed that the fuel distribution changed unsteadily. In particular, the fluctuation was large near the cavity attached to the combustor, and periodic fluctuation was obseved. (Fig. 1)

(4) Thrust performance of airframe-integrated external nozzles of hypersonic aircraft under various environmental conditions in external flows and pressures was evaluated based on numerical simulation. The simulation tool was developed based on OpenFOAM. Results showed that the external-nozzle configuration with the boattail equiped upstream of the primary thruster and with the external nozzle designed by the method of characteristics had significant benefits in thrust performance under any conditions compared to that by the baseline (simple divergent nozzle) configuration. (Fig. 2)

(5) Since a total temperature loss may occur due to heat loss to water-cooled walls of a supersonic wind tunnel with vitiation air heater, which is used for direct-connect style combustion test of scramjet combustor models, 3D combustion CFD was applied to an internal flow of the facility to evaluate the total temperature loss. (Fig. 3)

(6) A ramjet mode flow field in a scramjet combustor with large scale separation was predicted with a RANS method. For finer prediction, modification of turbulent St number through the Scalar Fluctuation Model and/or the compressibility correction was applied. Prediction of a flow field through Pseudo-shock system for pressure recovery remained inadequate. (Fig. 4)

Fig.1(video): Periodic fluctuation of equivalence raito distributions

Fig.2: (a) Pressure distribution around the airframe and nozzle under stable cruise condition at flight Mach number 5.0 for the configuration with the boattail, (b) Influence of the angle of attack on the thrust performance

Fig.3: Numerical grid for simulation to evaluate heat loss of test flow into water-cooled walls of supersonic wind tunnel with vitiation air heater: Unstructured grid, 1/4 space, about 16M elements

Fig.4: Comparison of experimental and numerical pressure distributions under ramjet-mode operation with SFM application for RANS CFD

Publications

– Non peer-reviewed papers

[1] Hayashi, K., Matsuo, A., Kodera, M., Takahshi, M., and Tomioka, S., “Numerical Investigation of Turbulent Model on Shockwave/Boundary Layer Interaction,”, Proceedings of Symposium on Shock Waves 2019 in Japan, 2020.

[2] Takahashi, H., Munakata, T., and Sato, S., “Effects of Flight Conditions and Attitudes on Thrust Performance of Hypersonic Aircraft Equipped with Airframe-Integrated Linear-Spike Nozzles,” Proceedings of 51st Fluid Dynamics Conference and 37th Aerospace Numerical Simulation Technology Symposium 2019, JSASS-2019-2052-A, 2019.

[3] Nishiguchi, H., Kodera, M., and Tomioka, S., “Optimization of Mode Transition of a Dual-Mode Scramjet Combustor,” Proceedings of 32nd International Symposium on Space Technology and Science and 9th Nano-Satellite Symposium, 2019-a-36, 2019.

[4] Nishiguchi, H., “Study on the Improvement of Numerical Analysis Accuracy of a Dual-Mode Combustor Considering Two Combustion Modes,” Master’s thesis, 2020.

– Oral Presentations

[1] Takahashi, H., Munakata, T., and Sato, S., “Effects of Flight Conditions and Attitudes on Thrust Performance of Hypersonic Aircraft Equipped with Airframe-Integrated Linear-Spike Nozzles,” 51st Fluid Dynamics Conference and 37th Aerospace Numerical Simulation Technology Symposium 2019, 2019.

[2] Nishiguchi, H., Kodera, M., and Tomioka, S., “Optimization of Mode Transition of a Dual-Mode Scramjet Combustor,” 32nd International Symposium on Space Technology and Science and 9th Nano-Satellite Symposium, 2019.

Usage of JSS2

Computational Information

• Process Parallelization Methods: MPI
• Thread Parallelization Methods: N/A
• Number of Processes: 1000 – 2224
• Elapsed Time per Case: 144 Hour(s)

Resources Used

Fraction of Usage in Total Resources*1(%): 2.21

Details

Please refer to System Configuration of JSS2 for the system configuration and major specifications of JSS2.

*1: Fraction of Usage in Total Resources: Weighted average of three resource types (Computing, File System, and Archiver).

*2: Fraction of Usage：Percentage of usage relative to each resource used in one year.

JAXA Supercomputer System Annual Report April 2019-March 2020