Publication

Abstract : Turbine blade tips are subject to burn out owing to leakage flow. Tip clearance flow arises due to the flow of unexpanded hot combustion gas through the interstice between turbine rotor blade tip and fixed shroud. In the present study we are numerically analyzing the effect of 4 tip modifications like dimpled tip (DIM), double squealer tip (DSS), pressure side squealer tip (PSS), and suction side squealer tip (SSS) on a plain tip. The influence of tip modifications on the effectiveness of turbine was estimated using parameters such as total pressure loss coefficient and vorticity magnitude and loss estimation using correlations. The study was conducted for various tip clearances such as 0%, 1.5%, 2.3% and 5% with respect to the blade span. Linear turbine cascade with 5 blades were used for this study. Simulations are carried out using commercial CFD solver, ANSYS FLUENT 14.0. Standard cascade loss estimation correlation was used. In the midst of tip shapes tested, double squealer tip and dimpled tip seemed to have the pre-eminent total pressure loss coefficient diminution. Both tip modifications significantly reduces the clearance leakage through the space between tip and casing, which consecutively depreciate the secondary losses adjacent to the convex surface of the blade. Correlation for losses through cascade showed a linear relationship between tip clearance loss and tip clearance gap. These tip modifications can be used in any kind of turbo machines for better performance with improved efficiency.