Effect of Squealer Geometry Arrangement on a Gas Turbine Blade Tip Heat Transfer

Abstract

This study investigates the effect of a squealer tip geometry arrangement on heat transfer coefficient and static pressure distributions on a gas turbine blade tip in a five-bladed stationary linear cascade. A transient liquid crystal technique is used to obtain detailed heat transfer coefficient distribution. The test blade is a linear model of a tip section of the GE E3 high-pressure turbine first stage rotor blade. Six tip geometry cases are studied: (1) squealer on pressure side, (2) squealer on mid camber line, (3) squealer on suction side, (4) squealer on pressure and suction sides, (5) squealer on pressure side plus mid camber line, and (6) squealer on suction side plus mid camber line. The flow condition during the blowdown tests corresponds to an overall pressure ratio of 1.32 and exit Reynolds number based on axial chord of 1.1×106. Results show that squealer geometry arrangement can change the leakage flow and results in different heat transfer coefficients to the blade tip. A squealer on suction side provides a better benefit compared to that on pressure side or mid camber line. A squealer on mid camber line performs better than that on a pressure side.

Aerothermal Performance of Shroudless Turbine Blade Tips with Relative Casing Movement Effects

“…They showed that deeper cavities can reduce tip heat transfer. Azad et al [5,6] also showed the improvements of a attaching a squealer compared to a flat tip. Furthermore, they discussed different squealer arrangements and outlined their effects on tip heat transfer.…”

An Investigation of Groove Type Casing Treatment on Aerodynamic Performance of a Linear Turbine Cascade

“…For this reason, highly complex flow structures appear near the blade tip and lead to inefficiency in terms of aerodynamic performance. The leakage flow also does not contribute to work generation since the flow is not turned as the passage flow (Azad et al, 2002;Heyes et al, 1992;Krishnababu et al, 2009;Mischo et al, 2008). In addition to the aerodynamic aspect, the leakage flow causes higher thermal loads on the blade tip platform (Azad et al, 2002;Key & Arts, 2006).…”

“…It was noticed that cavity squealer tip reduced the leakage flow rate whereas an increase in the total heat transfer coefficient was observed compared to the flat tip. An experimental study by Azad et al (2002) on 6 different squealer tips in a linear turbine cascade revealed that suction side squealer offered better aero-thermal performance compared to cavity and pressure side squealer. Camci et al (2005) experimentally studied the aerodynamic characteristics of partial squealer rims in a single-stage, large-scale, low-speed, rotating axial flow turbine research facility (AFTRF) of the Pennsylvania State University.…”

Effect of film-hole configuration on film-cooling effectiveness of squealer tips

“…Compared with a flat tip, the rim and groove of a squealer tip increases the flow resistance of the tip leakage flow. Although the overall heat transfer rate on the cavity floor is also found less than a flat tip, thermal loads and stresses are more concentrated in the tip edge (Azad et al, 2000;Azad et al, 2002;Kwak and Han, 2002, 2003b, 2004. Thus, it is important to understand the detailed flow and heat transfer features, and film-cooling performances of the squealer tip.…”