Computational Finite Element Analysis of Adaptive Gas Turbine Stator-Rotor Flow Interactions for Future Vertical Lift Propulsion
Khine, Yu Yu
The objective of this work is to computationally investigate the impact of an incident-tolerant rotor blade concept on gas-turbine engine performance under off-design conditions. Currently, gas-turbine engines are designed to operate at a single condition with nearly fixed rotor speeds. Operation at off-design conditions, such as during hover flight or during takeoff, causes the turbine blade flow to excessively separate introducing performance degradations, excessive noise, and critical loss of operability. To address these issues, the benefits of using an incidence-tolerant rotor blade concept is explored based on a novel concept that articulates the rotating turbine blade synchronously with the stator nozzle vanes. This concept is investigated using a novel CFD/FSI framework based on finite element analysis. The model considers a complex single stage high-pressure turbine geometry with 24 stator and 34 rotor blades operating under combustor exit flow conditions. The rotor speeds investigated are 44,700 rpm, 33,525 rpm, and 22,350 rpm corresponding to the design point at 100% speed down to 51% speed during off-design flight mode. This study focuses on determining the optimal performance benefits possible by exploring the limits of rotor blade articulation angles, as well as reporting its impact over a broad range of rotor speeds at Army relevant conditions. The key variables of interest include moments on the blade suction surface, torque, power, and turbine stage adiabatic efficiency. Further, sensitivity analysis of the uncertainties in boundary conditions is conducted to determine its influence on turbine efficiency. The results show that it is possible to increase efficiency increases of up to 10% by articulating rotor blades at off-design conditions thereby providing critical leap ahead design capabilities for the US Army Future Vertical Lift (FVL) program.
This proceeding is published as Kozak, Nikita S., Luis G. Bravo, Muthuvel Murugan, Anindya Ghoshal, Yu Yu Khine, Yuri Bazilevs, and Ming-Chen Hsu. "Computational Finite Element Analysis of Adaptive Gas Turbine Stator-Rotor Flow Interactions for Future Vertical Lift Propulsion." In AIAA Propulsion and Energy 2019 Forum, AIAA 2019-4176. 2019. DOI: 10.2514/6.2019-4176.