Centrifugal compressor having an asymmetric self-recirculating casing treatment

摘要

A centrifugal compressor includes an asymmetric self-recirculating casing treatment that includes, on an inner face of a casing 10, a suction ring groove 1, a ring guide channel 2 and a back-flow ring groove 3 to form a self-recirculating channel. An axial-direction position S_r from an upstream end face of the suction ring groove to an impeller full blade leading edge 4 or a width b_r of the suction ring groove 1 is represented as A(α·D−β·D)²+A₀ and is distributed in a parabolic shape in a circumferential direction. An initial phase angle θ₀ is in a range of 0≦θ₀≦2π. A circumferential angle α of the casing has a definition range of θ₀≦α≦θ₀+2π. In the expression, A denotes a parameter of the parabola in the axial-direction position S_r or the width b_r, and A₀ denotes an extreme of the axial-direction position S_r or the width b_r when corresponding circumferential angle β and the α are equal at an extreme point of distribution of the parabola.