JAXA Supercomputer System Annual Report (April 2018-March 2019)

Fundamental Study on Fluid and Combustion for Hypersonic Flight(Evaluation of Influence of Turbulence Intensity)
Report Number: R18EG3207
Subject Category: Research and Development
URL: https://www.jss.jaxa.jp/en/ar/e2018/9140/
Responsible Representative
Kouichi Okita, Director, Research Unit IV, Research and Development Directorate
Contact Information
Yasunori Nagata (Okayama University) (ynagata@okayama-u.ac.jp)
Members
Masahiro Takahashi, Yasunori Nagata
Abstract
In the engine combustion test using the hypersonic wind tunnel facility, high temperature, high pressure, andhigh velocity flow is generated by combustion heating upstream of the nozzle. However, in this process, theturbulence of the flow and the contamination by the combustion gas are occurred unavoidably. Therefore, it isconcern that the different situation is observed between ground test and actual flight because of these unavoidablefactors. In this study, we focus on the mixing process of the injected fuel and the free-stream, and aim to evaluate
the influence of the free-stream turbulence on the jet mixing. Thus, we develop a CFD analysis method for thisevaluation by introduction of the free-stream turbulence model and validation through comparison with windtunnel experiment result.
Reasons for using JSS2
Because of the unsteady phenomenon of jet mixing, we need to compare about statistical values between thenumerical and experimental results. To do this, wide enough time range of numerical data should be obtained,
which takes a lot of computational time. In addition, although it is possible to handle the shear layer which isimportant in the jet mixing phenomenon appropriately in LES calculation, a fine calculation grid is required, andthe calculation time per time step becomes longer. Furthermore, since it is necessary to carry out the several casesof the different flow condition, the whole computational cost becomes large. Therefore, we need to use JSS2 withhigh computing performance.
Achievements of the YearAs a preliminary step of the free-stream turbulence case, LES calculation of the no turbulence case is carried out
and compared with the jet mixing experiment performed in the supersonic wind tunnel of Okayama University. It
compared with the distribution of the mean jet mole fraction obtained by the experiment using plane laser induced
fluorescence (PLIF) technique, and confirmed that it is able to simulate well by LES calculation about the mixing－251－

This document is provided by JAXA.

JAXA Special Publication JAXA-SP-19-003E

condition of the jet (Fig. 1, 2). We also tried to introduce the free-stream turbulence using Random Flow
Generation (RFG) method. In addition, because our LES calculation code was only compatible with thread parallelby OpenMP, it is modified to be also compatible with process parallel by MPI, which is suitable to obtain highcomputational efficiency on JSS2.

Fig. 1: Mean jet mole fraction distribution of supersonic jet mixing field (nitrogengas for free-stream and jet, 0.8 mm in jet hole diameter)

Fig. 2: Mean Mach number distribution of supersonic jet mixing field (nitrogen gasfor free-stream and jet, 0.8 mm in jet hole diameter)

Publications
N/A－252－

This document is provided by JAXA.

JAXA Supercomputer System Annual Report (April 2018-March 2019)

Usage of JSS2

Computational Information
Process Parallelization Methods

MPIThread Parallelization Methods

OpenMP

Number of Processes

1 - 64

Elapsed Time per Case

100 Hour (s)Resources Used
Fraction of Usage in Total Resources*1 (%): 0.01
Details
Computational Resources
System Name

Amount of Core Time(core x hours)

Fraction of Usage*2 (%)

SORA-MA

86,464.31

0.01

SORA-PP

0.00

0.00

SORA-LM

0.00

0.00

SORA-TPP

0.00

0.00

File System Resources
File System Name

Storage Assigned (GiB)

Fraction of Usage*2 (%)

/home

10.73

0.01

/data

1,316.07

0.02

/ltmp

2,197.27

0.19

Archiver Resources
Archiver Name

Storage Used (TiB)

J-SPACE

Fraction of Usage*2 (%)
0.18

0.01

*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.

－253－

This document is provided by JAXA.