О влиянии на характеристики выходных диффузоров числа Маха за последней ступенью турбины

Abstract

Using CFD the computational investigation of two axisymmetric and axiradial cones (diffusers) typical for the exhaust branch pipes of steam turbines was carried out in the wide range of the pressure variation at the entrance of the cones with available tip-clearance leakage. As the pressure decreased the Mach number at the cone entrance increased. It has been established that in subsonic modes the cone with continuous external by-pass without the circular blade had the flow without separation and considerably lower values of loss coefficients in comparison with the diffuser that has a projection of the internal by-pass and the circular blade. At trans-sonic rates the coefficients of total losses of both studied cones are increased reaching the values that exceed 1 and have similar values; however the coefficients of internal losses and exit velocity losses differ significantly.