列车交会空气压力波测量的影响因素

Influential Factors of Measuring Air Pressure Pulse Produced by Passing Trains

研究了连接动态压力传感器的信号线长度、放大器的滤波频率和数据采集系统的采样频率对空气压力波测量的影响。研究结果表明,当传感器信号线长度小于100m时,对传感器输出的动态信号影响不大于1%,满足列车交会空气压力波实车测量要求;放大器的滤波频率和数采系统采样频率对空气压力波的测试结果均有较大影响,应采用带低通的应变放大器,滤波频率以100Hz为宜;随着采样频率的增加,测量得到的空气压力波幅值增大,采样频率增加到1kHz后,测量结果趋于稳定。在列车交会空气压力波实车测试中,为保证测试的准确性,节省设备内存空间,采样频率取1kHz较合适。

The effects of the signal line length, the filter and the sampling frequencies on measuring air pressure pulse were studied in this paper. The results show that when the signal line length of sensor is less than 100 m, its influence on sensor dynamic signal will be less than 1%. It meets the real train test requirement of measuring crossing air pressure pulse. The filter and the sampling frequencies have evident influence on the results of measuring air pressure pulse, so the strain gauge magnifier with the low-pass, and whose filter frequency 100 Hz is supposed to be adopted for measuring crossing air pressure pulse of real train test. It also shows that the measured magnitude of air pressure pulse increases with increasing the sampling frequency until the sampling frequency reaches 1 kHz. In order to reach the factuality of the wave shape and save memory the sampling frequency should be set at 1 kHz.