JAXA Supercomputer System Annual Report February 2025-January 2026

Report Number: R25EACA63

Subject Category: JSS Inter-University Research

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• Responsible Representative: Ko Ogasawara, Tokyo Univercity of Science
• Contact Information: Atsuki Yoshida(7525570@ed.tus.ac.jp)
• Members: Kohei Koyama, Ko Ogasawara, Jinto Suzuki, Kento Tashiro, Atsuki Yoshida

Abstract

The aim of this study is to simulate aerodynamic heating around a vehicle flying at hypersonic speeds in the atmosphere and to identify flight conditions and vehicle designs that help reduce heat flux to the surface.

The expected outcome is a reduction in convective heat flux during hypersonic flight for fully reusable launch vehicles and hypersonic air crafts. As a result, this would reduce the weight of thermal protection systems for high-speed vehicles, ultimately improving the feasibility in terms of overall system's weight.

Reference URL

N/A

Reasons and benefits of using JAXA Supercomputer System

Currently, for obtaining analytical values of the aerodynamic performance and thermal protection of upper-stage rockets and lifting bodies, extensive meshes for boundary layer resolution and high-precision calculation methods are computationally feasible using JAXA supercomputer.

Achievements of the Year

We are investigating the use of strakes to improve the low-speed lift performance of a lifting-body reentry vehicle. However, sharp leading-edge geometries such as strakes are expected to cause severe aerodynamic heating in the hypersonic flight regime.

To address this trade-off, we focused on the possibility of a leading-edge geometry that can both withstand aerodynamic heating during hypersonic flight at high angles of attack and improve low-speed lift characteristics through a sharp leading edge. As a first step toward assessing the feasibility of such a geometry, we conducted hypersonic CFD simulations using OpenFOAM on an asymmetric cylinder model with a compound-radius leading edge composed of two different radii. A schematic of the asymmetric cylinder is shown in Fig. 1.

Figure 2 shows the heating-rate distribution around the cylinder leading edge for the case combining radii of 4 mm and 8 mm. A notable feature is the inflection point that appears around theta = -10 deg.

Figure 3 shows the circumferential velocity field around the cylinder leading edge. As seen in Fig. 3, the stagnation point is located on the larger-radius side. In contrast, Fig. 2 indicates that the maximum heat flux occurs on the smaller-radius side. This reveals a distinctive phenomenon that differs from that of a conventional circular cylinder: the location of maximum heat flux is shifted away from the stagnation point.

Future work will include evaluating the improvement in low-speed lift performance and investigating shock-wave interactions in greater detail.

Fig.1: Schematic of the asymmetric cylinder

Fig.2: Heat-flux distributions for Case 3 (R1 = 4 mm, R2 = 8 mm, sweep angle = 0 deg) and Case 9 (R1 = 4 mm, R2 = 8 mm, sweep angle = 70 deg)

Fig.3: Circumferential velocity distributions for Case 3 (R1 = 4 mm, R2 = 8 mm, sweep angle = 0 deg) and Case 9 (R1 = 4 mm, R2 = 8 mm, sweep angle = 70 deg)

Publications

- Oral Presentations

Kohei Koyama, and Ko Ogasawara,"Study on Relationship Between Local Geometry of Strake Leading Edge and Peak Aerodynamic Heating",The 2025 Asia-Pacific Symposium on Aerospace Technology:APISAT-2025

Usage of JSS

Computational Information

• Process Parallelization Methods: MPI
• Thread Parallelization Methods: Automatic Parallelization
• Number of Processes: 100 - 240
• Elapsed Time per Case: 48 Hour(s)

JSS3 Resources Used

Fraction of Usage in Total Resources*1(%): 0.34

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