| 摘要 |
PURPOSE:To improve the performance of the once-through type fan by a method wherein the shape of casing at air guiding side is formed into a proper shape to optimize airflow at the blow-off side of the casing. CONSTITUTION:The air guiding side casing 3 is formed so that the beginning end A of a curved surface 3A is located at the suction side from a horizontal line 7 passing through the center of a runner 1 within the range of alpha=25 deg.-40 deg. in order to prevent generation of vortex due to the airflow of the suction side of the fan. The shape of the curved surface 3A is formed so as to be a logarithmic spiral shape and an arbitrary distance (r) of the curved surface 3A from the center of the runner 1 is shown by a formula r=r0eLQ. Here, r0 shows the distance between the beginning end A of the curved surface 3A and the center of the runner 1 while L shows the expanding amount of the curved surface 3A and it is called generally as an expanding rate. theta is an expanding angle from the beginning end A of the curved surface 3A. Here, ranges of L=0.15-0.25 and theta=120 deg.-140 deg. are set and whereby the airflow of the blow-off side may be optimized. According to this method, airflows at the suction and blow-off sides may be optimized and the performance of a compressor may be improved.
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