Centrifugal rotation machine

Abstract

This centrifugal rotation machine (1) comprises: a rotary shaft (2) that rotates about an axis; a plurality of impellers (3) that send out a fluid by rotating with the rotary shaft (2); a casing (5) that is provided so as to surround the rotary shaft (2) and the plurality of impellers (3), the casing (5) defining a return flow path (18) that guides the fluid (G) from a front-stage-side impeller (3) to a rear-stage-side impeller (3); and a plurality of return vanes (25) provided in the return flow path (18) along the circumferential direction of the axis (O) with intervals therebetween. The return flow path (18) includes a return bend section (21) that guides, radially inwardly, the fluid (G) which has been sent out radially outwardly from the front-stage impeller (3). The return bend section (21) includes a first curved section (27), and a second curved section (28) connected on the downstream side of the first curved section (27). The radius of curvature of the radially inside wall surface of the second curved section (28) is made greater than the radius of curvature of the radially inside wall surface of the first curved section (27).

Description

technical field [0001] The present invention relates to a centrifugal rotary machine such as a centrifugal compressor that compresses gas by centrifugal force. [0002] This application claims priority based on Japanese Patent Application No. 2013-013728 for which it applied on January 28, 2013, and uses the content here. Background technique [0003] As is well known, a centrifugal compressor passes gas in the radial direction of a rotating impeller, and compresses fluid such as the gas by utilizing the centrifugal force generated at this time. As such a centrifugal compressor, there is known a multistage centrifugal compressor that includes multistage impellers in the axial direction and compresses gas in stages (see Patent Document 1). This multistage centrifugal compressor will be briefly described with reference to the drawings. [0004] like Image 6 As shown, the centrifugal compressor 101 includes a casing 5 having a suction port and a discharge port not shown, a r...

AI Technical Summary

Problems solved by technology

[0012] However, in the above-mentioned conventional centrifugal compressor 101, there is a problem that the fluid G is separated on the hub shell 5b side (radially inner side) of the inlet of the return plate 125, causing a pressure loss.

As a result, the frictional loss increases and the separation of the fluid G occurs, hindering the uniformity of the flow at the inlet position of the return plate 125, and the pressure recovery in the downstream part is insufficient, resulting in a loss of the efficiency of the centrifugal compressor.

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