Investigation of ultrasonic system for measurement of slow gas flow velocity

Abstract

It is shown that for measurement of slow rate gas flow velocity (v£0.2-0.3m/s) one of the most perspectives is the multichannel ultrasonic measuring system. On the basis of experimental investigation it is revealed that one of the most important reason limiting the accuracy of slow flow velocity measurement is the zero drift of ultrasonic measuring system. It is determined that the most significant influence on the zero drift produces the instability of spoolpiece temperature and possible gradients of temperature in the measuring section. For diminishing of the influence of zero drift it is proposed to investigate the dependence of zero drift on the spoolpiece temperature in the whole region of possible temperatures. The values of sound velocity, which are obtained by measuring process, are proposed to use for determination of measuring gas temperature. When determining the flow velocity it is suggested from the values of flow velocity obtained by the measuring process to subtract the values of zero drift which where determined under the same sound velocity. After such correction of measuring results the influence of the zero drift of ultrasonic system on the results of gas flow velocity measurement may be decreased to the value 1-2mm/s.