多声路超声流量计积分方法及其准确度分析

Integration method of multi-chord ultrasonic flowmeter and its accuracy analysis

超声流量计属于速度式流量计,多声路超声流量计需要进行复杂运算才能得到流量,其采用的数学模型对测量准确度有着非常重要的意义。分析了超声流量计的流量积算原理,介绍了2种Gauss型的声路布置方案,推算了各自的声路高度与权重系数。Gauss型积分方案之所以存在截断误差,是由于实际声路速度无法为相应阶数的代数多项式所精确表达。Gauss型积分方案的平均流速并非简单的面积加权平均值,而是提高了中间部分声路的权重系数,其积分准确度明显优于面积加权平均,且声路数越多,积分准确度越高。

Ultrasonic flowmeter is a velocity-type flowmeter.The mathematic model it adopts is very important to its measurement accuracy.Integration theory of the flowmeter is introduced in this paper;two sensor arrangement schemes are analyzed and the pairing sensor positions and their weight coefficients are calculated.The cause of the integration error is that the actual distribution of the measured velocity can not be expressed by algebraic polynomials with corresponding order.Gauss integration scheme does not just simply use area weighting average as the average flow rate,but increases the weights of the middle acoustic lines.Its integration accuracy is obviously better than the area weighting method;and the more the number of acoustic lines is,the better the accuracy is.