Three Dimensional Flow Investigation in One and a Half Stage Axial Turbine

Abstract

In this study, three dimensional flow analysis of one and a half stage axial turbine is investigated. The objective of this study is to analyse the effect of rotor stator interaction and the resulting unsteadiness. This includes the effect of first row of Nozzle guide vane (NGV) wakes on rotor blades, secondary vortical flow prediction, influence of rotor wakes on the flow pattern of second stator, appreciation and application of techniques to model the exact blade counts across the rotor-stator interfaces. We employ a three-dimensional finite-volume based solver to simulate the flow in the turbine using SST model to account for turbulence effects. Sliding mesh technique is used to allow the transfer of flow parameters across the sliding rotor/stator interfaces. In order to model a single passage configuration, profile transformation and time transformation method is used. The flow physics for the visualization and understanding of flow behavior in a 3D turbine cascade is explained in detail and validated with the previous experimental and numerical studies. The study provides application of computationally efficient methods for simulating the fluid flow in a turbine which contain unequal number of rotor and stator blades.