Numerical investigation on aerodynamic characteristics of exhaust passage with consideration of multi-factor components in a supercritical steam turbine

Heat transfer and vacuum in the condenser are affected by the flow characteristics in the low-pressure steam turbine exhaust passage. In this study, the Eulerian-Eulerian equilibrium two-phase model is applied to investigate the contribution of multi-factor components on aerodynamic performance of twin exhaust passage. Results show that the share of steam phase is reduced in the exhaust passage with consideration of the built-in pipelines. Total-pressure loss in the exhaust hood is about four times of that in the throat. The sensitivity of local loss existing in the exhaust hood on the whole loss is higher than that in the throat. Considering the factors of LSBs and pipelines, both the static-pressure recovery coefficient of 15.44% and effective specific enthalpy-drop of 0.145% are the best performance. By evaluating the steam turbine economic, however, static-pressure recovery coefficient and specific enthalpy drop are 1.25 times and 0.475 times of that without pipelines, respectively, relative to built-in pipelines. Therefore, a recommendation on the consideration of twin exhaust passage, last stage blades, steam extraction pipelines, low-pressure heater, and wet steam can obtain a representative aerodynamic characteristic.