JAXA Supercomputer System Annual Report February 2025-January 2026

Report Number: R25EDA201J04

Subject Category: Aeronautical Technology

PDF (to be added)

• Responsible Representative: Kazuyuki Nakakita, Aviation Technology Directorate, Fundamental Aeronautics Research Unit
• Contact Information: Shingo Matsuyama(matsuyama.shingo@jaxa.jp)
• Members: Kosei Goto, Shingo Matsuyama

Abstract

It is known that aerodynamic heating rate, real gas aerodynamic characteristics, and static and dynamic instabilities, which are important prerequisites for the design of atmospheric entry systems, change significantly with changes in capsule shape, but they also change with different representative lengths (scales), even for similar shapes. However, there is no quantitative correlation known to what extent changes in scale affect these properties, so it is necessary to predict them at each design stage. The objective of this study is to develop a method for predicting scale effects for a 3/5 scale capsule and a wind tunnel model of HTV Small Re-entry Capsule (HSRC), and to validate the developed method by comparing it with flight data.

Reference URL

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Reasons and benefits of using JAXA Supercomputer System

In this study, three-dimensional analyses are performed for an atmospheric entry capsule flying at an angle of attack, so a large computational cost is inevitable. In addition, since turbulence analysis by Large Eddy Simulation (LES) is the main method for evaluating dynamic instability in transonic speeds, a large-scale three-dimensional unsteady analysis is inevitably required. In addition, for flight conditions exceeding Mach 10, the governing equations for a large number of chemical species and internal energies must be solved because chemical reactions and excitation of internal energy modes occur behind the shock wave. These analyses are computationally very expensive and require the use of a supercomputer.

Achievements of the Year

- LES analysis was performed on a capsule-shaped model scaled down to a three-fifths scale of the HSRC (Fig. 1). The LES analysis was used to evaluate whether capsule oscillations would be amplified due to dynamic instability when flying at angles of attack outside the trim range.

- The oscillation motion of the capsule model was simulated by LES for a pitch free-to-rotate wind-tunnel test with one degree of freedom (Fig. 2), and the results were compared with the wind-tunnel test data.

Fig.1: LES analysis of a capsule flying at an attitude away from trim angle. Instantaneous pressure field around the capsule is shown.

Fig.2: Results of LES analysis for a pitch free-to-rotate wind-tunnel test conducted in a transonic wind tunnel. The effect of grid resolution on capsule oscillation was evaluated.

Publications

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Usage of JSS

Computational Information

• Process Parallelization Methods: MPI
• Thread Parallelization Methods: OpenMP
• Number of Processes: 59 - 175
• Elapsed Time per Case: 480 Hour(s)

JSS3 Resources Used

Fraction of Usage in Total Resources*1(%): 0.45

Details

Please refer to System Configuration of JSS3 for the system configuration and major specifications of JSS3.

*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.

ISV Software Licenses Used

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

JAXA Supercomputer System Annual Report February 2025-January 2026