Effects of Inlet Swirl on Suction Side Phantom Cooling

Though the temperature of the coolant injected from the endwall increases after the mixing process in the main flow, the injections moving from the endwall to the airfoil suction side still have the potential of second order cooling. This part of the coolant is called "Phantom cooling" in the paper. This paper is focused on the function of the coolant from fan-shaped. holes on endwall surface which brought by passage vortex to the airfoil suction side. The test cascades are based on the profile of General Electric Energy Efficient Engine (GE-E-3), with the inlet Mach number of 0.1 and Reynolds number of 1.46x10(5). The scale ratio of the test vanes is 1.95 and the film cooling effectiveness is tested with Pressure Sensitive Painting (PSP) Technology. Nitrogen is used to simulate the coolant which can provide a density ratio near 1.0. Two adjacent passages are investigated simultaneously by which the film cooling effectiveness can be compared in the same case on the suction side surface. The inlet rotating flow is simulated by an upstream swirler at the inlet, fixed at 5 different positions along the pitchwise direction. They are Blade 0 aligned, Passage 1 aligned, Blade 1 aligned, Passage 2 aligned and Blade 2 aligned. According to the experimental results, the inlet rotating flow can dominate the film cooling effectiveness distribution at the Suction Side. The averaged film cooling effectiveness changes substantially with the change in the swirler position. The inlet swirling flow effects are compared on the adjacent vanes at upstream and downstream regions. The research shows that the different pitchwise position of the inlet swirler is a significant factor which can change the phantom cooling phenomenon on the suction side. The relative position of inlet swirler cannot be ignored for Nozzle Guide Vane design.