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ACTA AERONAUTICAET ASTRONAUTICA SINICA ›› 2017, Vol. 38 ›› Issue (11): 121236-121236.doi: 10.7527/S1000-6893.2017.121236

• Fluid Mechanics and Flight Mechanics • Previous Articles     Next Articles

Measurement technique for turbulence level in compressible fluid by changing overheat ratio of hot-wire

DU Yufeng, LIN Jun, MA Husheng, XIONG Neng   

  1. China Aerodynamics Research and Development Center, Mianyang 621000, China
  • Received:2017-03-13 Revised:2017-06-13 Online:2017-11-15 Published:2017-06-12

Abstract:

Turbulence level is important in high speed wind tunnel experiments. Research on measurement techniques for turbulence level in compressible fluid is carried out to satisfy the need of tests with high accuracy in high speed wind tunnel. Based on the law of heat convection, response function of constant temperature hot-wire anemometer is derived in detail. Sensitivities of mass flux and total temperature are obtained, and the algorithm for the turbulence level in compressible fluid is built. Turbulence level measurement tests are carried out with Mach number varying from 0.3 to 0.6. Using the response function proposed above as a mathematical model, the data are fitted based on the hyperbola fitting method. The turbulence level is around 0.3%-0.6% when the Mach number varies from 0.3 to 0.6. The frequency spectrum of the hot-wire output voltage is analyzed. According to the characteristics of the frequency spectrum, the signal is processed using low-pass filtering, and the effect of voltage spike in the time domain on the solution for turbulence level is reduced effectively. The turbulence level is around 0.1%-0.3% after filtering with Mach number ranging from 0.3 to 0.6, and the results are almost the same with results obtained previously. The results validate correctness of the solution for turbulence level and feasibility of application of the technique of changing the overheat ratio of the constant temperature hot-wire anemometer for turbulence level in compressible fluid.

Key words: compressible fluid, turbulence level, constant temperature hot-wire anemometer, overheat ratio, response function, hyperbola fitting, low pass filtering

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