AIR INTAKE PIPE STRUCTURE FOR CENTRIFUGAL FLUID MACHINE

摘要

An object is to provide an air intake duct structure for a centrifugal fluid machine, capable of swirling the fluid introduced into the impeller in the reverse direction to increase the pressure ratio when the flow rate is high and swirling the fluid in the forward direction to avoid a surging when the flow rate is low, as well as securing a wide operating range, without using mechanical means. The centrifugal fluid machine 1 includes an impeller 12 mounted to a rotation shaft and a housing 4 for housing the impeller 12. The air intake duct structure 10 is for directing a fluid "f" to a rotational center 12a of the impeller 12 housed in the housing 4 via an intake duct portion 4a of the housing 4 protruding in an axial direction of the rotation shaft, the fluid "f" flowing in a substantially orthogonal direction to a rotational axis line 3. The air intake duct structure 10 comprises an inflow part 14 extending in the substantially orthogonal direction to the rotation axis line 3 and a transition part 16 connecting the inflow part 14 and the intake duct portion 14a of the housing 4. There is a virtual plane 20 orthogonal to the rotational axis line 3 and passing through a flow path cross-section of the inflow part 14, where an intersection 22 of the virtual plane 20 and the rotational axis line 3 is positioned within the transition part 16.