半導体レーザ2焦点流速計による遠心送風機旋回失速の計測 : 第2報,流れ変動だ円による旋回失速の解析

抄録

Fundamental knowledge for detecting and predicting the inception of rotating stall was investigated. The measured blade-to-blade variation of velocity fluctuation was analyzed on the conception of the flow-fluctuation ellipse which indicates the fluctuation ranges of velocity vector and correlation coefficient based on the covariance between the tangential and radial components of velocity fluctuation. It was cleanly indicated that, (1) the inception of rotating stall was closely related to the three-dimensional separation of boundary layer on the diffuser wall, and (2) the rotating stall inception could be predicted experimentally by detecting the variation of correlation coefficient at the impeller exit. That is, it is presumed that the rotating stall will occur if the value of correlation coefficient becomes close to zero and then larger than zero, on if the local separation zone originated in the vaneless diffuser reaches the impeller exit.