音速喷嘴式气体流量标准装置试验分析

Experimental Analysis of Sonic Nozzle-type Gas Flow Standard Device

基于音速喷嘴式气体流量标准装置校准原理,对标准装置的测量精度、密封性和背压比等计量特性进行了试验分析研究。通过固定音速喷嘴螺母不同拧紧力矩对比试验,验证了音速喷嘴安装不到位所导致的内部泄漏会给测量结果造成较大误差。背压比试验得出,实际临界背压比可由音速喷嘴所在具体装置通过试验比较后获得,通过调整抽风机压力,适当降低实际背压比,可保证标准装置的测量精度,使标准装置的稳定性达到0.09%;同时评定的标准装置的扩展不确定度为0.38%(k=2)。试验分析对标准装置的检测及量值溯源具有一定的借鉴意义。

Based on the calibration principle of the sonic nozzle-type gas flow standard device, the measurement characteristics of the standard device, such as measurement accuracy, sealing performance and back pressure ratio, were experimentally analyzed and studied. The comparison test of the different tightening torque of fixed sonic nozzle nut verified that the internal leakage caused by improper installation of sonic nozzle would cause a significant error to the measurement result. The actual critical back pressure ratio can be obtained by comparing the specific device where the sonic nozzle is located. By adjusting the suction fan pressure and appropriately reducing the actual back pressure ratio, the measuring accuracy of the standard device can be guaranteed, and the stability of the standard device can reach 0.09%. The extended uncertainty of the standard device is 0.38%(k=2). The experimental analysis above has a particular reference significance for the detection and value traceability of the standard device.