Investigation on Variable Guide Vane (VGV) Unsteady Flow Characteristic of Axial Turbine

Abstract

An investigation is conducted on the unsteady flow characteristic of a variable turbine guide vane. Subsequently, an analysis is performed on the unsteady flow characteristic under three situations, namely, no gap, partial gap, and full gap at the endwall of a variable guide vane. Investigation result demonstrates that an obvious leakage flow will occur when a partial gap or a full gap is present at the endwall of a variable turbine guide vane. Such leakage flow will cause turbine grade loss to deteriorate. The periodic unsteady effect will be evident when the running rotor blades cut through the leakage flow. Pressure and temperature pulsations will both be higher when the gap at the endwall is full compared with when it is partial.