PREREVOLUTION DEVICE FOR COMPRESSOR

PURPOSE: To prevent the generation of noise owing to a Karman vortex by a method wherein an intake air flow flowing through a moving vane is collected to the impeller side and development of turbulence at an intake air flow flowing through the moving vane is suppressed by protruding a flow straightening sheet to point the flow of intake air from the vane surface of a specified moving vane toward the impeller side. CONSTITUTION: A lever 6 serving as a mechanism to rotate moving vanes 4 in synchronism with each other is coupled to the rotary shaft 5 of each moving vanes 4 and the tip part of the lever 6 is coupled to a link 9 through a pin 8. By rotationally driving the rotary shaft 5 by means of an actuator, the moving vanes 4 are synchronously rotated through the ring 9. Further, a flow straightening sheet 7 to point a flow of intake air from the vane surface 12 on the suction side of a specified moving vane 4 toward an impeller 2 is protruded. The sheet-form flow straightening sheet 7 is protruded at right angles with the vane surface 12 of the moving vane 4. This constitution collects a flow of intake air flowing through the moving vanes 4 toward the impeller 2 and prevents the occurrence of turbulence of the intake air flow to prevent the generation of noise.