| 摘要 |
PURPOSE:To reduce the dynamical radial thrust generation in a low flow rate region by setting the magnification factor of the cross sectional area of the flow path along the radial direction of a diffuser to be larger on the crown side of a blade wheel than that on the shroud side. CONSTITUTION:Inlet blade angles and the cross sectional areas of the outlet flow path of the first diffuser blade wheel 7 and the second diffuser blade 8 of a blade wheel 1 provided on a main shaft 2 are set to the same values. And, the magnification factor of a flow path cross sectional area in the radial direction of a diffuser blade wheel 8 on the crown 1b side is set larger than that of a diffuser blade wheel 7 on the shroud 1a side. Hereby, the overall stall is caused on the second diffuser blade wheel 8 side when operating in a low flow rate region, and the uniformity in the circumferential direction is attained by the first diffuser blade wheel 7 side, so that dynamical radial thrust is largely reduced. |
