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采用热线风速仪(HWA,Hot Wire Anemometry)测量了D300mm×2000mm圆管内旋转流切向瞬时速度随时间的变化特征。测量结果表明在圆管的中心区域,瞬时切向速度随时间的波动变化较大,而靠近边壁区域瞬时切向速度随时间的波动变化较小,中心区域瞬时切向速度的脉动幅值远大于壁面区域的脉动幅值。通过对瞬时切向速度进行频谱分析可知,瞬时切向速度的波动频率沿径向和轴向基本一致,但在出口区域频率有所增大,圆管内的瞬时切向速度出现低频波动是旋转流的摆动导致的。
Hot wire Anemometry (HWA) was used to measure the characteristics of the instantaneous velocity with the passage of time in the D300mm × 2000mm circular tube. The measurement results show that the instantaneous tangential velocity varies greatly with time in the central area of the pipe, while the instantaneous tangential velocity changes little with time in the area near the wall, and the amplitude of the instantaneous tangential velocity in the central area is much larger Fluctuation amplitude in the wall area. The frequency analysis of instantaneous tangential velocity shows that the frequency of instantaneous tangential velocity is basically the same along the radial direction and the axial direction, but the frequency increases in the exit region. The low frequency fluctuation of the instantaneous tangential velocity in the circular tube is the rotational flow Caused by the swing.