进气道风洞试验气体流量计实况校准技术

Actual-Calibration Technique of Gas Flowmeters in Inlet Wind Tunnel Test

关键词:  风洞试验  进气道  实况校准  气体流量计  进气流量

Key words:  Wind tunnel test  Inlet  Actual-calibration  Gas flowmeter  Air intake flow

摘要:

为更精确地测量飞行器进气道风洞试验中流量参数，对进气道低速风洞试验中使用的小流量气体流量计开展实况校准方法研究，在FL-8风洞研制了一套工作压力小于0.1MPa，喷嘴Ma≤1，进气流量m≤2kg/s的基于音速喷嘴的可移动流量计校准系统。考虑到雷诺数与马赫数对流出系数的影响，采用依据实际风洞试验流量计工作状态参数的原则选取校准点；采取在流量计实际工作地点校准的方式以减小系统误差，校准后直接安装进气道模型进行风洞试验。试验结果表明：该校准方法重复性和装置稳定性良好，解决了现有流量计校准与实际试验中流动状态不一致，造成流出系数不准确的问题。有校准修正的流量要比无校准修正的流量相差2%~3%，由此引起进气道的性能参数差量达1%~2%。因此，该实况校准方法可有效减小测量误差，提升进气流量测量精准度。

Abstract:

In order to more accurately measure flow parameters in aircraft inlet wind tunnel tests， an actual-calibration method under test conditions of gas flowmeters for small flow was investigated. A movable flowmeter calibration system based on a sonic nozzle with working pressure less than 0.1MPa， whose nozzle Mach number was less than or equal to 1， and the inlet flow rate less than or equal to 2kg/s was developed in the FL-8 wind tunnel. Considering the influence of Reynolds number and Mach number on the discharge coefficient， the principle of selecting calibration points based on the actual working state of the flowmeter in wind tunnel tests was established. To reduce system errors， the method of calibration was adopted at the actual working site of the flowmeter. After calibration， the inlet model could be directly installed for tests. The experimental results indicate that the calibration system has good repeatability and stability， which solves the problem of inaccurate flow coefficients caused by inconsistent parameter settings between calibration and actual tests. The deviation of flow rate with calibration is 2%~3% compared with that without calibration， which causes the deviation of inlet parameters reach to 1%~2%. Therefore， this actual-calibration method can effectively reduce measurement errors and improve the accuracy of intake flow measurement.