声学风洞流场低湍流度及频谱测量研究

采用热线风速仪对5.5m×4m 低湍流航空声学风洞闭口试验段低湍流度流场进行测量,根据对干扰信号的分析,提出了高通惯性衰减滤波方法,并与一般数据处理方法进行了比较,给出了流场测量方案、方法和结果。采用功率谱方法和斯特罗哈数方法分析脉动速度信号中的干扰噪声,发现40Hz~10kHz 频谱范围内同时存在电磁干扰噪声和支架干扰噪声。比较分析了0.5Hz~5kHz 带通滤波方法、电磁噪声解耦方法和0.5Hz 高通惯性衰减滤波方法对干扰信号的滤除效果,采用0.5Hz 高通惯性衰减滤波方法获得了流场低湍流度数据,流场速度30~100m/s 的湍流度平均值小于0.05%。实验结果表明,高通惯性衰减滤波方法可以有效控制干扰信号对测量结果的影响程度,为低湍流度流场信号处理提供了一种方法。

Low turbulence intensity and spectrum measurement research in aeroacoustic wind tunnel

The 5.5m×4m low turbulence aeroacoustic wind tunnel is a low speed single-re-turn wind tunnel,capable of performing aeroacoustic,low turbulence and general low speed tests.The flow of this tunnel presents the important quality of low turbulence intensity,which needs to be measured accurately.The band pass filter and signal noise separation are the two main methods to process the low turbulence intensity data.However,the parameters of the two methods are different,and thus there is no direct comparison between their results.In this paper the low turbulence intensity of the flow field is measured in the closed test section of the 5.5m× 4m low turbulence aeroacoustic wind tunnel with the hot wire anemometry.A 0.5Hz high pass inertia attenuation filter is adopted to process the data according to the noise analysis,and the re-sults are compared with other two methods,that the 0.5Hz~5kHz band pass filter and the sig-nal noise separation.Noises in the flow field fluctuation are analyzed based on the power spec-trum and the Strouhal numbers.The electromagnetic noise and support disturbing noise are found in spectrum domain of 40Hz~10kHz.Using a 0.5Hz high pass inertia attenuation filter, the flow field turbulence intensity is measured and found to be less than 0.05% at the speed of 30~100m/s.Experimental results show that,the high pass inertia attenuation filter method can be used to control the disturbance to the results induced by noises,which is a practical method for processing the low turbulence intensity digital signal.