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

Research for Future Transportation System (Research for Scramjet Engine Flow Path)
Report Number: R18EG3104
Subject Category: Research and Development
URL: https://www.jss.jaxa.jp/en/ar/e2018/9135/
Responsible Representative
Shigeru Sato, Researcher, Research Unit 4, Research and Development Directorate
Contact Information
Shigeru Sato, Researcher, Research Unit 4, Research and Development Directorate (sato.shigeru@jaxa.jp)
Members
Shigeru Sato, Toshihiko Munakata, Masaaki Fukui, Masaharu Takahashi
Abstract
The purpose is to investigate the influence of the internal flow path on the engine performance by help of CFD
in the viewpoint of aerodynamics about a scramjet engine as a reusable space propulsion engine, and to contributeto designing a scramjet engine.
In other words it is to compare the engine results with CFD in order to extract effective factors on improvementof the engine performance from a lot of experimental results of engine tests stored in Kakuda Space Center, andto make CFD simulation about a trial engine configuration which is proposed for engine performance
improvement.
Ref. URL: https://repository.exst.jaxa.jp/dspace/handle/a-is/877173
Reasons for using JSS2
In Kakuda Space Center, scramjet engine is being investigated, and a lot of engine performance tests have been
made by using Ramjet Engine Test Facility (RJTF). It has been found in the tests that the difference of engine
inner configuration produces large difference of thrust performance in the flight condition of Mach 6. CFD
simulations are being carried out based on the plenty of engine test data stored in Kakuda Space Center about how
the difference of engine inner configuration of main elements of the engine, inlet, isolator, strut and others influent
on the engine performance, and CFD simulations on trial engine configuration not yet tested are also carried out.
Aerodynamic effects of engine inner configuration are investigated by using CFD, compared with the engine
tests, and systematized to prepare basis for decision for designing of scramjet engines.
Achievements of the Year
In order to compare to the result of engine configuration already tested in RJTF (Ramjet Engine Test Facility)
located in Kakuda Space Center, a virtual engine test is being carried out about an improved engine configuration.
The configuration has a boat-tail strut of which the tail is shortened and narrowed in order to improve the engine－265－

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thrust performance, though it has the same basic dimension to the tested engine. Figure 1 shows the tested engine
outline. Figure 2 shows the difference of engine inner quantity in the both engine configurations.
A commercial code ANSYS Fluent is applied to this calculation, and structured grid system is used. Theminimum grid size is set by 0.1mm near the cowl leading edge. The calculation is done in the half of the engine
model assuming mirror condition in the engine symmetric center plane. The number of grids at the maximum is5.03x106. The limiter is the second order accuracy, space integral is AUSM+, time integral is explicit method, andturbulence model is k-omega model. For the combustion calculation, a model used here is the model of Fluent
including Hydrogen-Oxygen reaction equation based on the Petersen and Hanson.*) This time Finite RateChemistry Model is employed for the combustion calculation, and the reaction consists of 9 species and 20
elementary reactions.
Engine air flow condition for calculation is set at Mach 5.3 in the engine entrance, and total temperature is set at1500K. RJTF nozzle exit boundary layer (57.9mm thickness / 99.9% of main stream velocity) is also set in theflows into the engine, which corresponds to the boundary layer on the air frame bottom surface.
The calculation is performed mainly on JAXA’s present Supercomputer System the 2nd Generation, JSS2. It is
used remotely from Kakuda Space Center.
Figure 3 gives the equivalence rato distributions in combustion flow. Fig. 3a shows the 5/5-Height strut
configuration, and Fig. 3b shows the Boat-tail strut configuration. The both are the equvalence ratio contours inthe engine exit. In the 5/5-Height strut configuration the equivalence ratio distribution is almost simulated, butprotrusions are left in the both corners close to the tap wall along the both side walls showing higher value thanthe expeimental value. On the other hand, in the boat-tail strut configuration the equivalence ratio much more
spreads, and the equivalence ratio more than 1.0 is hardly seen. In the comparison, it is confirmed that the boat
tail strut configuration relatively has an effect of spreading the fuel in the engine cross section.
Figure 4 gives the combustion efficiency distributions oppositely to the above. Fig. 4a shows the 5/5-Heightstrut configuration, and Fig. 4b shows the Boat-tail strut configuration. The both are the combustion efficiency
distribution at the engine exit. The efficiency less than 0.8 is seen in the middle of the engine cross section, which
is not seen in the RJTF experimant result. On the other hand, in the boat-tail strut configuration the highcombusiton efficiency is seen allover the engine cross section due to the equivalence ratio spread. In the CFD
comparison the boat tail strut configuraton will show better performance.
It is needed to research the engine inner flow by increasing the CFD accuracy and to find origins of thrust product.
Finding the origins will make it possible to build methods to create the engine performance.
*) Petersen, E.L. and Hanson, R.K., Journal of Propulsion & Power, Vol. 15, No. 4, July-August 1999.

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

Fig. 1: Outline of scramjet engine tested. The engine is set upside-down on the test bed,
and 5/5-hieght strut is equipped.

Fig. 2: Two types of strut for CFD comparison. a) 5/5H-Strut configuration is used in engine test,and b) the Boat-tail Strut configuration is an improved one designed as a virtual configuration. (unit: mm)－267－

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JAXA Special Publication JAXA-SP-19-003E

Fig. 3: Calculated equivalence ratio phi distribution at the engine exit in the combustion flow.

Fig. 4: Calculated combustion efficiency eta distribution at the engine exit in the combustion flow.

Publications- Non peer-reviewed papers
1) Shigeru SATO, Masaaki FUKUI, Takahiro Watanabe, Masaharu Takahashi and Toshihiko MUNAKATA,
Shock Wave in Combustion in a Scramjet Engine, AIAA2019-0678, AIAA Science and Technology Forum andExposition (AIAA SciTech 2019), January, 2019, San Diego.

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

Usage of JSS2

Computational Information
Process Parallelization Methods

It depends on FLUENT

Thread Parallelization Methods

It depends on FLUENT

Number of Processes

4-8

Elapsed Time per Case

720 Hour (s)Resources Used
Fraction of Usage in Total Resources*1 (%): 0.00
Details
Computational Resources
System Name

Amount of Core Time(core x hours)

Fraction of Usage*2 (%)

SORA-MA

0.00

0.00

SORA-PP

0.00

0.00

SORA-LM

7.38

0.00

SORA-TPP

0.00

0.00

File System Resources
File System Name

Storage Assigned (GiB)

Fraction of Usage*2 (%)

/home

24.25

0.03/data

246.180.00/ltmp

1,432.29

0.12

Archiver Resources
Archiver Name

Storage Used (TiB)

J-SPACE

Fraction of Usage*2 (%)
0.36

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.

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