JAXA Supercomputer System Annual Report April 2017-March 2018

Report Number: R17ETET26

Subject Category: Skills Acquisition System

PDF available here

• Responsible Representative: Takashi Aoyama, Aeronautical Technology Directorate, Numerical Simulation Research Unit
• Contact Information: Masashi Kanamori kanamori.masashi@jaxa.jp
• Members: Masashi Kanamori, Takahiro Yoshikawa

Abstract

It is of a great importance to predict a so-called low-speed buffet phenomenon for realizing safer flight. During a flight with a high angle-of-attack condition in a low-speed regime, separated flow at a leading edge of main wing impinges on its tail, resulting in a hazardous vibration. Our research group works on a preliminary study on low-speed buffet by means of computational fluid dynamics (CFD) in order to grasp the essence of the phenomenon.

Reference URL

N/A

Reasons for using JSS2

It is absolutely necessary to prepare a computational grid with high-resolution near the separated zone in order to predict a low-speed buffet phenomenon accurately. The number of grid point is of the order of tens of millions, which is prohibitively large from a view point of a computation with a personal computer. The processing capability of JSS2 is therefore necessary for our research.

Achievements of the Year

Two models were considered in this study; NASA Common Research Model (NASA CRM) as model 1 and the same model without main wing as model 2 as shown in (Fig.1). Comparison of flowfield around each model were conducted by carefully calculating the effective angle of attack of the tail by subtracting a downwash from a flow velocity in the flowfield around model 1. (Fig. 2) presents a variation of lift coefficient of the tail against its effective angle of attack, clearly showing an apparent difference in lift coefficient at angle of attack of 8 degrees, at which model 1 began to stall. This indicates a clear correlation between a stall of main wing and a sharp drop of the lift of a tail.

Fig.1: model 1 and model 2

Fig.2: variation of lift coefficient of tail against effective angle of attack

Publications

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Usage of JSS2

Computational Information

• Process Parallelization Methods: MPI
• Thread Parallelization Methods: N/A
• Number of Processes: 512
• Elapsed Time per Case: 12.00 hours

Resources Used

Fraction of Usage in Total Resources*1(%): 0.20

Details

Please refer to System Configuration of JSS2 for the system configuration and major specifications of JSS2.

*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.

JAXA Supercomputer System Annual Report April 2017-March 2018