Large-eddy simulation study of rotating detonation supersonic turbine nozzle generated by the method of characteristics under oscillating incoming flow

Abstract

Rotating detonation turbine engine is receiving considerable attention due to its' high cycle efficiency, outstanding thrust characteristics, self-pressurization, and energy-saving attributes. Conventional turbines are inefficient (30%) under rotating detonation inflow conditions. In order to obtain the turbine operating efficiently under the condition of rotating detonation inflow, this paper uses the method of characteristics and Bessel parameterization to design the blade profile of the rotating detonation supersonic turbine. The Large Eddy Simulation is used to numerically study the flow field characteristics of the supersonic turbine blade designed by the method of characteristics. The study found that the rotating detonation supersonic turbine guide vane can effectively reduce the pressure oscillation amplitude of the incoming flow to 25% of the original amplitude, and the main frequency (10 kHz) of the incoming flow occupies the main part of the flow field frequency. Second, the morphological evolution of the shock waves attenuates the adverse pressure gradient on the suction surface. The separation area of the suction surface slowly oscillates and attenuates, and is eventually confined to a small region. The wake accelerates and dissipates under the squeezing jet of the dovetail wave and the intense shearing action, forming a small wake area. The attenuation of large-scale separation gradually reduces the separation loss and wake loss, and the convergence and interaction of shock waves and the wake vortex significantly enhance the proportion of entropy production in the shock region. From the pressure coefficient and is entropic Mach number distributions, it is found that the blade load is mainly concentrated in the tail, and is minimized when the flow field becomes stable. These features provide a reference for the design of rotating detonation supersonic turbines and a deeper understanding of the flow field characteristics of rotating detonation turbine engines.