高精度管道漏风量测试仪的设计及实验研究

High-precision pipeline air leakage tester design and experimental research

现有的国产漏风量测试仪普遍存在测量精度低、自动化水平低的问题,为此,基于漏风量测试仪的原理,开展了漏风量测试仪的结构设计、系统设计及整机实验研究。首先,对漏风量的测量过程、喷嘴流量测量原理进行了研究,推导了喷嘴流量测量公式,并根据相关标准设计了角接取压方式的喷嘴结构,基于仪器操作便捷性要求,对整机结构进行了设计;其次,采用空气密度补偿公式完成了高精度流量自适应测量,设计了基于自锁式电磁阀的换向调零电路,采用换向调零法对压差传感器零点漂移进行了补偿,使用小波阈值去噪算法消除了信号噪声,提高了流量的测量精度;采用抗积分饱和比例积分微分(PID)算法对流量进行了闭环控制;最后,研制了管道漏风量测试仪样机,开展了压差与流量测量精度与重复性实验。实验及研究结果表明:该高精度漏风量测试仪工作状态稳定,压差测量精度为±0.4%,流量测量精度为±2%;该漏风量测试仪的测量精度优于国内同类仪器,符合国家标准要求,具有良好的市场前景。

Aiming at the problems of low measurement accuracy and automation level air leakage tester,the principle research,structural design,system design and whole machine experiment research of the air leakage tester were carried out.First of all,the measurement process of air leakage and the flow measurement principle of nozzle were researched,the flow measurement formula of nozzle was deduced,the nozzle structure with angle joint differential pressure measurement was designed according to the relevant standards,and the structure of the whole machine was designed based on convenient operation.Then,the high precision flow adaptive measurement was realized by applying the air density compensation formula,a commutation zero adjustment circuit based on the self-locking solenoid valve was designed to compensate for zero drift of differential pressure sensors by applying changing-direction zero adjustment method,the flow measurement accuracy was improved and the noise of signal was eliminated by applying the wavelet threshold denoising algorithm,and the anti-windup proportional integral derivative(PID)algorithm was used to control the flow closed-loop.Finally,a prototype of the pipeline air leakage tester was developed,and the accuracy and repeatability experiments of pressure and flow measurement were carried out.The experimental results show that the designed high-precision air leakage tester works stably,with a pressure difference measurement accuracy of±0.4%and a flow measurement accuracy of±2%;the measurement accuracy of the designed air leakage tester is superior to similar domestic instruments and complies with requirements of national standard,with good market competitiveness.