Experimental measurement on the air test rig of the axial steam turbine exhaust casing

Abstract

This paper describes the aerodynamic design of the scaled air test rig of axial exhaust casing. The axial exhaust casings are used to benefit steam turbines of less than 180 MW, and their design can significantly affect the performance of the last stage and thus the performance of the entire steam turbine. The proposed test rig, along with extensive CFD simulations, will help to optimize the flowing in the exhaust casing and provide the ability to reliably predict losses in the exhaust casing on real steam turbines. Part of the study will be the detection of the influence of the individual components of the velocity at the diffuser inlet, the effect of the number, shape and arrangement of the internal struts. Last but not least, the effect of a wall jet blowing into the outer diffuser wall will be studied. The aerodynamic design of the test rig itself required a lot of numerical simulations to achieve the desired velocity profile at the diffuser inlet. It has been shown that it is difficult to simulate the radial component of the velocity in experimental conditions. The desired circumferential component of the velocity can be achieved more easily by suitable shaping of the stationary blade grid at the diffuser inlet.This paper describes the aerodynamic design of the scaled air test rig of axial exhaust casing. The axial exhaust casings are used to benefit steam turbines of less than 180 MW, and their design can significantly affect the performance of the last stage and thus the performance of the entire steam turbine. The proposed test rig, along with extensive CFD simulations, will help to optimize the flowing in the exhaust casing and provide the ability to reliably predict losses in the exhaust casing on real steam turbines. Part of the study will be the detection of the influence of the individual components of the velocity at the diffuser inlet, the effect of the number, shape and arrangement of the internal struts. Last but not least, the effect of a wall jet blowing into the outer diffuser wall will be studied. The aerodynamic design of the test rig itself required a lot of numerical simulations to achieve the desired velocity profile at the diffuser inlet. It has been shown that it is difficult to simulate th...