| dc.description.abstract | This study investigates the impact to power generation and efficiency by injecting flow into the tip clearance region of a gas turbine rotor. New to this design is using a fluidic oscillator as the jet source for the injection instead of a circular jet. The fluidic oscillator in this study is a bistable, vent fed oscillator. It creates a sweeping jet at its exit with a primary frequency in the 1 kHz to10 kHz range dependent on the supply mass flow and internal geometry. In this study, rotor tip clearance in the range of 2% to 10% of blade span is investigated for the flowing rotor tip types: flat tip, 2 and 4 fluidic oscillators on a flat tip, circle jets on a flat tip, squealer tip, 4 fluidic oscillators on a squealer tip, and circle jets on a squealer tip. This study was performed using the commercial CFD package STAR-CCM+. A polyhedral mesh was used for enhanced accuracy and reduced compute times. The significant flow models used were implicit unsteady, k-e turbulence, and real air. Also the turbine rotor was rotated about the z-axis (cylindrical) to simulate a real rotor. Only two blades of the entire rotor were simulated using periodic boundary conditions to simulate the rest of the rotor wheel. The tips with 4 fluidics showed the largest efficiency gain of 2% to 3% over the flat tip, 0% to 1% over the squealer tip, and about 1% over the circle jet tips. The 4 fluidic tips produced nearly twice as power per orifice as compared to the circle jet tips. The 2 fluidic tip had an efficiency gain of about 1% over the flat tip, an efficiency loss compared to the squealer tip, and 0% to 0.5% gain over the circle jet tips. The 2 fluidic tip produced 12% to 40% more power than the circle jet tips. The two 4 fluidic tips and the 2 fluidic tip created more turbine power that in took the compressor to make the supply air. However, when compared to the power production of the squealer tip, almost all tip configurations did not produce more power than it took to make the supply air. | |
