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开展了可压缩流中湍流度测量技术的研究,以满足高速风洞高精度试验能力的需求。以对流换热规律为基础,从理论上对可压缩流中热线金属丝热平衡关系式进行了推导,以此为基础,详细推导了恒温热线风速仪的响应关系式,得到了质量流量和总温灵敏度系数的显式表达式,建立了可压缩流中湍流度的求解方法。在马赫数为0.3~0.6范围内进行了湍流度测量试验,以响应关系式为数学模型,利用双曲线拟合方法对试验数据进行了拟合分析,求解得到了马赫数在0.3~0.6范围内流场湍流度约为0.3%~0.6%。对热线输出电压进行了频谱分析,根据频谱特性,利用低通滤波对频域信号进行了处理,有效降低了时域信号脉冲尖峰对湍流度求解的影响,滤波后求解得到马赫数在0.3~0.6范围内流场湍流度约为0.1%~0.3%,与前期测量结果相符。试验结果证明了所建立理论方法的正确性及利用恒温热线风速仪变过热比方法测量可压缩流湍流度的可行性。
The study of turbulence measurement technology in compressible flow was carried out to meet the needs of high-speed wind tunnel high-precision test capability. Based on the law of convection heat transfer, the heat balance relationship of hot wire in compressible flow was deduced theoretically. Based on this, the response equation of constant temperature hot wire anemometer was deduced in detail. The mass flow rate and total temperature The explicit expression of the sensitivity coefficient establishes the method of solving turbulence in compressible flow. Turbulence measurements were carried out in Mach number range from 0.3 to 0.6. In response to the mathematical model, the test data were fit and analyzed by hyperbolic fitting method. The Mach number was found in the range of 0.3 ~ 0.6 Flow turbulence is about 0.3% ~ 0.6%. According to the spectrum characteristics, the low-pass filter is used to process the frequency domain signal, which effectively reduces the influence of the signal spike in the time domain on the solution of the turbulence degree. After filtering, the Mach number is found to be between 0.3 and 0.6 Within the range of turbulence flow rate of about 0.1% to 0.3%, consistent with the previous measurement results. The test result proves the correctness of the established theoretical method and the feasibility of measuring the turbulent flow of compressible flow by the method of changing the overheat ratio of the thermostatic hot wire anemometer.