两相流中固体散料对器壁压力的测量

MEASUREMENT OF PRESSURE EXERTED ON THE WALL BY PARTICLES IN A TWO-PHASE FLOW

测量两相流中固体散料对器壁的压力时,必须设法消除散料空隙中的气体或液体之压力对测量的影响。本文研制的一种高灵敏度应力——应变型传感器不仅可以测量常压下散料对器壁的压力,而且可以准确测量加压下散料对器壁的压力。实验表明该传感器反应迅速、线性度好、灵敏度高。

The pressure exerted by fluid-particle flow on the wall of the pipe is composed of two parts: fluid pressure and particle pressure. In general, the fluid pressure is several hundred times higher than the particle pressure, therefore the accurate measurement of the particle pressure is more difficult. In this work a stress-strain type wall pressure transducer has been developed and used for measuring the particle pressure exerted on the wall of the trapezoidal pipe for pneumatic moving bed uptransport. In this trapezoidal pipe the gas pressure was as high as 200000 N/m^2, the particle pressure was lower than 2500 N/m^2. The wall pressure transducer consists of a diaphragm, a strain beam, a free beam, a force-transfer glass ball, two micro-screen electric resistance type strain gauges The diaphragm, strain beam, and free beam are made from 0.15mm thickness Be-Bronze plate. This transducer was mounted in the wall of the pipe and combined with a electric resistance type strain instrument to output the millivolt signal as long as the pressure was exerted on the diaphragm. A fluid pressure balance tube connects the pipe with the cavity of the transducer in order to balance the fluid pressure exerted on the two sides of the diaphragm and to measure the particle pressure. However, the experiments found that the wall of the pipe strains under a higher fluid pressure, which causes the additional strain of the diaphragm, so that extra millivolt output is produced. This extra millivolt output should be subtracted from the total millivolt output and the extra millivolt value can be obtained by calibrating the transducer under different fluid pressure without particles at the same position of the pipe. The experimental results shown that this wall pressure transducer possesses the advantage of high sensitivity, high accuracy, quick response and good linearity.