Computational fluid dynamic (CFD) analysis of the region the secondary flow path of high pressure steam turbine was conducted. Region included two adjacent to disc cavities and section of main flow path. The cavities were channeled by balance holes located in the disk. Two geometrical models were considered: single disk cavity and both cavities with balance holes. 2D axi-symmetric and 3D analyses were conducted for the first model, however only 3D study was performed for the second one. Analysis of the single disk cavity has revealed appearance of vortexes in circumferential direction even in case when all boundary conditions and geometry features were close to the axi-symmetric case. The trend of the average pressure distributions along radius was found for 2D and 3D models. The transient analysis of the two cavity model revealed vortexes movement in circumferential direction with higher than disk rotation velocity. It induces periodic conditions at the inlet and outlet of balance hole and periodic steam mass flow rate through the holes. The flow pattern in the two cavities with balance holes is so complicated that common 1D net flow representation should be considered as significant simplification.
展开▼
