COMPARISON OF DIFFERENT SHROUD CONFIGURATIONS IN HIGH-PRESSURE TURBINES USING UNSTEADY CFD

摘要

The objective of this work is to analyze the end wall leakage interaction in shrouded high pressure turbines to provide useful indications about the flow pattern and its impact on performances. The prediction of flow through the seal and the understanding of the leakage jet interaction with the main flow in turbine end wall regions is nowadays possible using 3D CFD approaches. Modern solvers allow the coupling of the labyrinth and the main vane flows accounting for most of the geometric and aerodynamic features characterizing this phenomenon. Two similar shroud configurations are here analysed for two high pressure turbine configurations. Each configuration refers to a different blade technology commonly used by ANSALDO ENERGIA. The computational algorithm is based on a numerical solver developed and applied for the simulation of compressible Navier-Stokes equations in a multi rows unsteady environment. In order to reproduce the basic physic of the leakages, the problem has been investigated modelling the unsteady 1 1/2 stage interaction together with the complete geometry of the labyrinth seals. The CFD results are commented addressing the potential source of losses to help the development of solutions for reducing the leakage losses.