On the stall flutter occurrence in a blade cascade set to turbine and compressor geometry

¹ The Czech Academy of Sciences, Institute of Thermomechanics, Dolejškova 5, Praha 8, CR
² UWB, FAS, Department of Mechanics, Universitní 8, Plzeň, CR
³ UWB, FME, Department of Power System Engineering, Universitní 8, Plzeň, CR

^* Corresponding author: prochap@it.cas.cz

Published online: 11 July 2022

Abstract

A blade cascade allowing free pitch movement of five blades was developed in Institute of Thermomechanics. This model is introduced to study the phenomenon of stall flutter existing in rotary bladed wheels of steam turbines and other devices. This article describes how to induce the stall flutter for prescribed boundary conditions (as inlet velocity, various angles of attack, etc.) and gives survey about flow field differences around the cascade set to both the turbine and the compressor geometry. This experimental research utilized time-resolved Particle Image Velocimetry (PIV) to measure and to evaluate statistical quantities of the wake behind the NACA0010 profiles of the cascade. Also dynamical analysis was performed in the form of Fast-Fourier transform and also phase-locked measurement was applied. Gained knowledge will be utilized to design advanced model of the cascade allowing stall flutter examination without the use of ball bearings.