亚声速可压缩流场叶片边界层热线测速方法研究

Velocity measurement of blade boundary layer in subsonic compressible flow field with hot wire

为了能够开发一种简单有效的亚声速可压缩流场叶片边界层速度测量方法,从而为叶型设计和相关数值研究工作提供支撑,本文围绕热线风速测量技术,针对可压缩流场密度变化对热线标定结果的影响,以及实际测量中速度、密度耦合而无法直接获取的问题,通过理论分析,提出了适用于边界层测量的恒定压力热线标定方法和引入叶表稳态静压进行速度解耦的方法,并对所提出方法的主要误差进行了分析评估。在此基础上进行了热线标定和边界层速度测量试验验证,明确了恒定压力热线标定数学模型系数随压力的线性变化规律,同时针对温度非线性影响提出了一种基于过热比调整的修正方法,该方法能够将约13℃的温度偏差对热线电压的影响降低到1%以内,进一步简化了恒定压力热线标定流程,结合基于叶表稳态静压的速度解耦方法,为亚声速可压缩流场叶片边界层瞬态速度测量提供了一种简单可行的高频响测速方法。

In order to develop a simple and effective method for measuring the blade boundary layer velocity in subsonic compressible flow field,then providing useful information for the blade design and numerical simulation,the measurement technology of hot-wire anemometer is focused on in this paper.In view of the influence of density change on the calibration results of hot-wire in compressible flow field,the hot wire calibration method based on the constant pressure control which is suitable for boundary layer velocity measurement was proposed.While for the velocity and density coupling problems that cannot be directly obtained by the hot wire measurement in the compressible flow field,the velocity decoupling method by introducing the steady static pressure on blade surface was also introduced,and the main errors of the proposed methods were analyzed and evaluated.On this basis,the hot wire calibration and boundary layer velocity measurement verification tests were carried out,and the results show that the coefficients of the hot wire calibration mathematical model based on the constant pressure control change linearly with the pressure.At the same time,a correction method based on overheat ratio adjustment was proposed to solve the nonlinear effect of temperature,which can reduce the effect of temperature deviation of about 13℃on the hot wire voltage to less than 1%.So the hot wire calibration processes based on the constant pressure control are simplified furtherly.Combining with the velocity decoupling method based on the steady static pressure on the blade surface,a simple and feasible velocity measurement method with high-frequency response characteristic for the blade boundary layer in the subsonic compressible flow field is provided.