高精度液压系统压力波传递速度在线测量试验

管内流体压力波传递速度是分析研究液压系统稳定性和动态品质的基础物理参数。从传输管路波动方程出发，推导三传感器测量原理，引入Foster等价剪切系数模型，对液压管路中各种影响因子进行高精度估计，采用Newton-Raphson迭代法减小数据处理误差，精确计算压力波传递速度。基于理论推导，搭建液压管路压力波传递速度在线测量试验平台，用MATLAB软件编程，实现了液压系统多种工况下压力波传递速度的精准测量与计算。试验结果表明：系统在典型的工作压力20 bar、50 bar、75 bar和100 bar下，压力波传递速度大约分别为1 320 m/s、1 338 m/s、1 363 m/s、1 380 m/s,所测结果在置信水平为95%的波速区间内误差在±1%范围内；管路压力波传递速度大小随工作压力的升高而增大，并依据试验结果给出了二者之间的函数关系；精确计算压力波传递速度需考虑管路材料对系统柔性的影响。试验和分析结果对液压系统管路压力波传递速度在线测量和预估具有重要指导意义和参考价值。

On-line measurement test of pressure wavespeed in hydraulic system with high precision

The pressure wavespeed of pipe flow is the basic physical parameter to analyze and study the stability and dynamic quality of hydraulic system. The three-sensor measurement theory was deduced based on the wave equation of the transmission pipeline, the Foster equivalent shear coefficient model was introduced for high-precision estimation of various influence factors in the hydraulic line, and the Newton-Raphson iterative method was adopted to reduce the data processing error and accurately calculate the pressure wavespeed. An on-line test platform for measuring pressure wavespeed of hydraulic pipeline was built based on theoretical derivation, realizing accurate measurement and calculation of pressure wavespeed of hydraulic system under various working conditions by MATLAB software programming. The test results show that: when the system is under the typical working pressure of 20 bar,50 bar,75 bar and 100 bar, the pressure wavespeed is about 1 320 m/s, 1 338 m/s, 1 363 m/s, 1 380 m/s respectively, and the measurement error is within ±1% in the wave speed interval with a confidence level of 95%; the pressure wavespeed of pipeline increases with the rise of the working pressure, and the function relationship between the two variables was given according to the test results; the effect of pipe material on system flexibility should be considered in the precise calculation of pressure wavespeed. The results of test and analysis have important guiding significance and reference value for the on-line measurement and estimation of pressure wavespeed in hydraulic system.