Experimental Research on the Flow in the Steam Turbine Axial Exhaust Hood

Abstract

There is the still remaining task to increase the efficiency of power plants and steam turbines. One possibility to increase the thermodynamic efficiency is to apply a suitable exhaust hood. Axial exhaust hoods are mainly designed for small turbines up to 180 MW. They are a very important part of steam turbines and its main purpose is to take away the steam from the last stage outlet to a condenser with minimal loss or even with pressure compression and an increase in the last stage enthalpy drop. This paper concerns experimental measurements on the axial exhaust hood wind tunnel model. The main goal of this paper is to determine how given geometrical and flow parameters affect the resulting pressure recovery coefficient. Main observed parameters are velocity and circumferential angle profiles at the diffuser inlet along with a number, shape and geometrical configuration of internal struts. Several geometrical variants are measured for two types of circumferential angles at the diffuser inlet and for two values of Mach number in the presented work. Multi-hole pneumatic probes and pressure taps are used for flow parameters measurement. The proposed experimental model, along with corresponding CFD (computational fluid dynamics) simulations, will help to optimize the flow parameters in the exhaust hood and allow a decrease in pressure losses in this part.