影响流量管流量系数的因素分析

对某航空发动机整机试验装置的流量管三维流场进行数值模拟，通过布置虚拟测点，建立流量管虚拟试验校准和测量的仿真方法，研究流量管流量系数获取方法、校准试验测试布局，分析来流雷诺数、壁面粗糙度、流量管圆度对流量系数的影响。结果表明，附面层位移厚度法和校准试验法获取的流量系数接近。在同一流向布置测量截面，流量系数随流量管内雷诺数的减小而减小，随流量管壁面粗糙度的增大而减小；低雷诺数工况下，流量系数对粗糙度变化不敏感。对于低雷诺数工况或者在流量管壁面粗糙度较大时，应采用附面层位移厚度法或校准试验法获取流量系数。流量系数对流量管圆度的变化不敏感，建议采用校准试验方法获得有变形的流量管的流量系数。尽量采用校准试验法获取流量管宽雷诺数范围的流量系数，采用实际测量工况下的雷诺数对应的流量系数，修正流量管测量数据，才可保证流量管测量精度。

Analysis of Factors Affecting Flow Coefficient of a Flow Tube

The three-dimensional flow field in the flow tube of an aeroengine test device is numerically simulated.By arranging virtual measuring points,the simulation method for calibration and measurement of the flow tube virtual test is established,the method for obtaining the flow coefficient of the flow tube and the layout of calibration test are studied,the effects of Reynolds number,wall roughness and roundness of the flow tube on the flow coefficient are analyzed.The results show that the flow coefficients obtained by measuring boundary layer displacement thickness and calibration test are close.In the same flow direction layout measurement cross-section,the flow coefficient decreases with the decrease of Reynolds number and the increase of roughness of the flow tube wall.Flow coefficient is insensitive to roughness change at low Reynolds number.For the condition of low Reynolds number or large roughness of flow tube wall,the methods of measuring boundary layer displacement thickness or calibration test should be used to obtain the flow coefficient.The flow coefficient is insensitive to the change of the roundness of the flow tube.It is suggested to use the calibration test to obtain the flow coefficient of the deformed flow tube.As far as possible,the calibration test is used to obtain the flow coefficient of the wide Reynolds number range of the flow tube,and the flow coefficient corresponding to the Reynolds number under the actual measured condition is used to correct the measured data,so as to ensure the measurement accuracy of the flow tube.