SEPARATION CONTROL ON LOW PRESSURE TURBINE BY PASSIVE TECHNIQUES

Abstract

In recent years CFD of turbo machinery flows has increased due to the enhanced computational power. Current trend in industry is to reduce the engine weight, size and enhance efficiency of engine components. This is done by manufacturing blades of higher efficiencies and reduced blade count. These trends in manufacturing result in highly loaded LPT blades. Due to the increased loading of blades, there is always a possibility of flow separation at low Reynolds number. In the last few decades, the reduction of fuel cost to weight ratio is the main concern of aero-engine manufactures and aircraft industry. Turbine engines are made to work properly and efficiently at high Reynolds's number (Re) conditions. The boundary layers (BL) of low-pressure (LP) turbine blades have received a great deal of attention due to the advent of high lift and ultra high lift LP turbines. At cruising condition the Reynolds number is very low in engine (low density and low velocity) and LP turbines performance suffers mainly from losses due to separationon suction side of the blade. In the present study T106A low pressure turbine profile has been used to study the behavior of BL and subsequent control using the passive technique. Geometry modification is being made to control the flow separation. Fluent® commercial CFD code with Gamma-Theta transition model has been employed to study the boundary layer separation at Reynolds number 91000. Passive devices control the separation very effectively which reduced the pressure loss coefficient or increased in efficiency of the LP Turbine.