JAXA Supercomputer System Annual Report February 2025-January 2026

Report Number: R25EG3214

Subject Category: Research and Development

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• Responsible Representative: Taro Shimizu, Research and Development Directorate, Research Unit III
• Contact Information: Hideyo Negishi(negishi.hideyo@jaxa.jp)
• Members: Ashvin Hosangadi, Hiroaki Amakawa, Yu Daimon, Taroh Fukuda, Hironori Fujiwara, Osamu Fukasawa, Hiroyuki Ito, Hideyo Negishi, Takenori Nakajima, Shinji Ohno, Masashi Toyama, Himeko Yamamoto, Andrea Zambon

Abstract

Turbopumps are still one of key components in liquid rocket engine development in terms of cost, time, and risks. Furthermore, a turbopump itself is a complex system consisting of sub-components such as pump, turbine, bearing, balance piston, sealing and so on. From numerical simulation technology point of view, there is no technology able to evaluate performance of an entire turbopump system in the world. And also, accuracy and fidelity of numerical simulation technology for sub-components are still poor and cannot be used to reduce the number of experiments. Therefore, experiments are indispensable to evalute feasibility of considered design in engine development.

In this study, numerical simulation technology of an entire turbopump system able to be applicable in engine design phase has been developed enhancing accuracy and fedelity. We are aiming at reducing cost and time for future engine development by making full use of our numerical simulation to reduce the number of experiments. And also, innovative design methodology for higher performance rocket turbopumps has been investigated by using our numerical simulations.

Reference URL

Please refer to https://stage.tksc.jaxa.jp/jedi/simul/index.html .

Reasons and benefits of using JAXA Supercomputer System

In this study, JSS3 has been used because of the following reasons:

(1) To make it possible to perform large-scale numerical simulations with high accuracy and fidelity

(2) To produce a lot of computed results on time within limited short period of time under JAXA's rocket development

(3) To ensure information security about rocket-related technical information in JAXA's network only

Achievements of the Year

For turbine analysis technology, in relation to the turbine flutter identified as a development issue for the LE‑9 engine, we applied our fluid‑structure two-way coupling analysis method (in-house CFD solver UPACS‑turbo, open source FEM solver FrontISTR and open-source coupler preCICE) to the stationary cascade flutter test (an outcome of the Aerospace Division's aFJR project) and successfully identified the conditions under which flutter occurs (Figure 1).

As for pump analysis technology, we advanced the enhancement of prediction methods for inducer suction performance, which has traditionally been difficult to model accurately. This fiscal year, we conducted a large-scale Large Eddy Simulation (LES) of the detailed inducer flow field with cavitation effects included, and demonstrated that the simulation reproduced the suction performance observed in the inducer cavitation tests conducted at the Kakuda Space Center more accurately than the conventional RANS-based method (Figure 2).

Fig.1: Comuted FSI simulation result for stationary cascade.

Fig.2: Computed result of inducer suction performance by LES simulation

Publications

- Oral Presentations

1) Hiroaki Amakawa, Hideyo Negishi, Hironori Fujiahra, Shinji Ohno, Junichi Kazawa, "Flutter Prediction in a Low-Pressure Turbine Stationary Cascade Using Fluid-Structure Interaction Analysis: Two-Way Coupling Study," The 39th symposium on computational fluid dynamics, 18th December, 2025.

2) Hideyo Negishi, Hiroaki Amakawa, Shinji Ohno, Hironori Fujiahra, , Junichi Kazawa, "Flutter Prediction in a Low-Pressure Turbine Stationary Cascade Using Fluid-Structure Interaction Analysis: One-way Coupling Study," The 39th symposium on computational fluid dynamics, 18th December, 2025.

3) Hideyo Negishi, Keita Yamamoto, Taroh Fukuda, Mitsuru Shimagaki, Satoshi Kawasaki, "Unsteady PIV Measurements and LES Analysis of Backflow Vortex Structures Upstream of a Rocket Engine Inducer," The 92nd academic meeting of Turbomachinery Society of Japan, 23rd May, 2025.

4) Keita Yamamoto, Mitsuru Shimagaki, Satoshi Kawasaki, Hideyo Negishi, "Evaluation of the Dynamic Behavior of a Rocket Engine Inducer," The 92nd academic meeting of Turbomachinery Society of Japan, 23rd May, 2025.

5) Hideyo Negishi, Keita Yamamoto, Taroh Fukuda, Mitsuru Shimagaki, Satoshi Kawasaki, "A Fundamental Study of Cavitation LES for a Rocket Engine Inducer," The 93rd academic meeting of Turbomachinery Society of Japan, 1st December, 2025.

Usage of JSS

Computational Information

• Process Parallelization Methods: MPI
• Thread Parallelization Methods: FLAT
• Number of Processes: 4992
• Elapsed Time per Case: 288 Hour(s)

JSS3 Resources Used

Fraction of Usage in Total Resources*1(%): 2.19

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