A numerical study is performed to simulate the leakage flow and heat transfer on a flat tip, a double squealer tip, and a single suction-side squealer tip of a scaled up General Electric-E3 blade. The simulations for a nonrotating blade at a pressure ratio of 1.2 are in reasonable agreement with the experimental data on the blade tip and suction side, but the heat transfer coefficients were overpredicted on the pressure side. Numerical simulations were then performed for nonrotating and rotating blades under high-temperature, high-pressure ratio, and high Mach number conditions to investigate the blade tip leakage flow and heat transfer characteristics under more realistic engine operating conditions. The simulation results show that the heat transfer coefficient decreases with increasing squealer cavity depth, but the shallow squealer cavity is the most effective configuration to reduce the overall heat load. The blade rotation produces a dramatic increase of heat transfer coefficient on the shroud. The tip leakage flow pattern and local heat transfer coefficient distributions on the blade tip are also significantly changed due to the rotation-induced centrifugal and Coriolis forces. However, the area-averaged heat transfer coefficient on the blade tip is only slightly affected by the blade rotation. Copyright © 2005 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.