JAXA Supercomputer System Annual Report February 2025-January 2026

Report Number: R25EACA60

Subject Category: JSS Inter-University Research

PDF (to be added)

• Responsible Representative: Koji Miyaji, Professor, Yokohma National University
• Contact Information: Koji Miyaji(miyaji@ynu.ac.jp)
• Members: Koji Miyaji, Kenichiro Takayanagi

Abstract

The static and dynamic attitude stability of high-speed flying objects are evaluated by numerical flow analysis. In particular, the High-Mach Integrated Control experiment (HIMICO), which is being researched and developed by JAXA and several universities, will be used as the analysis target, but verification will first be performed with a simplified geometry. Since wind-tunnel tests and theoretical values are hardly available for dynamic stability, the Newton flow approximation, a simplified method limited to hypersonic flows, will be extended to moving objects and treated as a theoretical solution to be compared with general-purpose CFD. In CFD, the accuracy and efficiency of the time evolution method for unsteady flows and the time spectral method for periodic steady flows will also be compared.

Reference URL

N/A

Reasons and benefits of using JAXA Supercomputer System

For steady and unsteady Computational Fluid Dynamics (CFD) aerodynamic analysis around high-speed flying objects, a supercomputer capable of high-speed calculations is necessary. In JSS3, not only self-developed codes but also execution of analysis tools provided by JAXA are possible.

Achievements of the Year

(Figure 1) shows the change in the stability derivative with respect to the center of gravity position, using a cone with a semi-apex angle of 10 degrees as a simplified shape, at a flight Mach number of 5 and an angle of attack a=0. The horizontal axis of the graph represents the center of gravity position relative to the total length, the left vertical axis is the vertical static stability derivative Cm_a, and the right vertical axis is the vertical dynamic stability derivative Cm_q with respect to the pitch angular velocity q. The Theory is an analytical solution using the Newtonian flow approximation, and the CFD is the result obtained by solving the flow around the aircraft undergoing forced oscillations over time. First, the agreement of Cm_a is good in both cases. In addition, in CFD, Cm_a'+Cm_q can be obtained from the pitch oscillation (where a' is the time derivative of a), and Cm_a' can be obtained from the heave oscillation, so it can be separated from Cm_q. The agreement of the calculation results for Cm_q is also good in both cases.

Next, (Figure 2) shows a simplified shape for lateral and directional motion analysis, for a cone with the main wing and vertical stabilizer added. (Figure 3) shows the lateral stability derivative for this shape. The directional stability derivative is similar to the longitudinal verification, so it is omitted here. In (Figure 3), the horizontal axis represents the dimensionless center of gravity position in the height direction from the central axis of the cone fuselage, and the vertical axis represents the rate of change of the rolling moment Cl and yawing moment Cn with respect to the roll angular velocity p. There are very few studies that discuss lateral and directional dynamic stability derivatives, but here too, the agreement between CFD and the Newtonian flow approximation is good, and we believe that this has provided verification for future analysis of complex aircraft shapes.

Fig.1: Comparison of CFD and Newtonian flow approximation for longitudinal stability derivatives of a simplified conical shape

Fig.2: Simplified shape of cone with the main wing and vertical stabilizer added

Fig.3: Comparison of CFD and Newtonian flow approximation for lateral stability derivatives for a simplified cone with the main wing and vertical stabilizer added.

Publications

N/A

Usage of JSS

Computational Information

• Process Parallelization Methods: MPI
• Thread Parallelization Methods: N/A
• Number of Processes: 72 - 576
• Elapsed Time per Case: 8 Hour(s)

JSS3 Resources Used

Fraction of Usage in Total Resources*1(%): 0.01

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