极低风速标定系统密闭室洞壁影响研究

Research on Sealed Chamber Wall Effects in an Extremely Low Wind Speed Calibration Facility

探头运动式极低风速标定系统密闭室洞壁干扰及前端壁扰动反射都可能对密闭室流场产生影响,从而影响标定精度。采用运动重叠网格技术,用URANS方程数值模拟密闭室流场,考察密闭室侧壁干扰、前端壁反射对流场和标定的影响。选择有洞壁和无洞壁情形计算密闭室流场,比较两种情形下的速度场;对于密闭室前端壁扰动反射问题,选择有前端壁和无前端壁两种边界条件,计算密闭室流场,比较不同时刻两种情形下的速度场。结果表明:洞壁干扰和前端壁反射引起的速度场偏差对标定的影响都在可接受范围内。

The side wall interference and disturbance reflection from the front end wall of a sealed chamber in an extremely low wind speed calibration facility operated by driving the probe in motion might have influence on the flow field inside the chamber,thus affecting the calibration accuracy.The moving overlapping grid technique is used in solving the URANS equations simulating the flow field in the chamber to investigate the effects of side-wall interference and the disturbance wave reflection from the front(upstream)end wall on the interior flow field and calibration.The flow fields in the cases with and without side walls are computed and compared.For the front end wall reflection of the strut rod disturbance,the boundary conditions with and without front end wall are used respectively in computing the flow field in the chamber,and the computed flow fields in the two cases are compared at several instants,respectively.The computed results show that the effects of velocity deviations caused by the wall interference and the front end wall reflection of disturbance on calibration accuracy are in an acceptable range.