Presently the losses of kinetic energy in the exhaust duct of low-pressure cylinder are considerable, since numerous spacer bars and directing plates are located inside. A fundamentally new approach is required to design the exhaust duct of LPC without internal elements in water passage and providing the decline of losses due to improvement of the diffuser form and collapsible chamber. The flow modeling in the considered exhaust duct design was carried out by the numerical RANS method with the SST turbulence model. To validate the CFD model, the results of the previous experimental studies of the basic design model were used. The comparison of the integral aerodynamic characteristics of the exhaust duct was carried out. For the basic variant of the exhaust duct, the variant without internal elements, and also for the variant without internal elements and with new geometry of the collapsible chamber, according to the results of the numeral experiment, distribution of pressure and vector fields of speeds in the exhaust nozzle are received and the integral parameters of the exhaust duct are defined. Advantage of the integral descriptions of the exhaust duct without internal elements and with a new form of collapsible chamber is proven. They are the coefficient of internal losses of the exhaust duct, the coefficient of kinematics unevenness of the stream, and the coefficient of repressuring in an axial-radial diffuser. It has been established that a new approach of geometry of the exhaust duct of LPC provides the improvement of their aerodynamic qualities when designing new high-powered steam-turbines to operate in TPP and NPP. The advantage of losses decline of energy in the exhaust duct is multiple, because the number of LPC streams in modern seam-turbines can amount up to eight.
Justification of nonstandard geometry of exhaust duct of steam turbine low pressure cylinder: case study of K-300-240-2 LMZ
