NUMERICAL INVESTIGATION OF TWO-PHASE WET STEAM FLOW WITH SPONTANEOUS CONDENSATION BASED ON EULER S2 CALCULATION METHOD

摘要

The Euler equation suitable for the S2 stream surface calculation is derived in the arbitrary orthogonal coordinate system firstly. The numerical method for the two-phase wet steam flow with the spontaneous condensation is then developed on basis of the Euler S2 calculation code, the Eulerian/Eulerian multiphase model and the classic nucleation theory. To adapt the complex geometry of the turbine blades, the Euler equations for the S2 stream surface calculation method are derived in the body-fitted coordinate system. The mathematical model for the third order TVD scheme with the non-conservative variables is also developed for the gas phase governing equation. The 2nd order NND and the VanLeer scheme are applied to the variable reconstruction and the numerical flux calculation respectively in the liquid equations solving process. The pressure and the droplet radii distribution fit well with the experimental data for both the high pressure nozzle and the low pressure nozzle. The S2 calculation method is also employed to predict the performance of a 3-stage low pressure steam turbine with spontaneous steam condensation, and the reasonable results are obtained. The numerical method developed in the present work is able to predict the real wet steam flow with the spontaneous condensation and its impact on the flow field and the aerodynamic parameters distribution reasonably, supplying a fast and accurate technic and method to the steam turbine design.