Japan Aerospace Exploration Agency Wind Tunnel Technology Center, Institute of Aerospace Technology
Japan Aerospace Exploration Agency Wind Tunnel Technology Center, Institute of Aerospace Technology
Japan Aerospace Exploration Agency Wind Tunnel Technology Center, Institute of Aerospace Technology
Cosmotec Co. Ltd.
Cosmotec Co. Ltd.
The JAXA 2 m x 2 m transonic wind tunnel utilizes total pressure and static pressure measured in the settling chamber and the plenum chamber respectively to compute Mach number. Very long period fluctuations of these pressures occur and it had been thought that such changes did not exert a significant influence on Mach number measurement. However, the pressure measurement systems employed very long tubes and it transpired that the phase difference between two measured pressures made the Mach numbers fluctuate. Consequently, the pipes having an optimal length and the inner diameter were designed and installed. To carry out this optimization, a computer program was developed that is capable of computing the response characteristics of pressure measurement systems without flow. The source code of the program is appended to the end of the report.