Session: 06-02 Pressure Gain Combustion

Paper Number: 153042

A Novel Design Methodology for Compact Turbine Stages Operating Downstream of Rotating Detonation Engines 

During last decades, more stringent regulations and a significant increase in environmental awareness by the legislators, pushed aviation industry to fulfil much tighter constraints to reduce aircraft pollutant emissions. Nowadays, one of the most promising solutions is represented by a new kind of combustion mode called Pressure Gain Combustion (PGC) allowing to improve the propulsion system efficiency. A forthcoming implementation of this technology is Rotating Detonation Engine (RDE) which burns fuel via a supersonically travelling, azimuthally rotating, detonation wave. This technology offers theoretical performance benefits in terms of efficiency, specific thrust and specific impulse with respect to conventional engines while it brings many challenges mostly related to the highly unsteady and non-uniform flow field generated by the travelling shock inside the combustor and the retrofitting it with a downstream turbomachinery. Indeed, potentially, low turbine performance has detrimental impact on the detonation cycles, hence a new class of turbomachinery, suitable to efficiently handle such a complex flow field, must be created. Open Literature is limited to those studies focusing on the design of large engines characterized by a significant axial extension and blades with very long axial chords which hinder additional compactness befits RDEs can offer. Based on the aforementioned research landscape, the current paper aims at designing a smaller, more compact and short length supersonic turbine, able to efficiently handle the complex flow field. New design methodologies, for a high pressure turbine stage, subjected to rotating detonation combustor (RDC) flow field, have been developed and detailed in this work. The full turbine stage design aims to ensure the self-starting capability of the cascade according to the Kantrowitz limit with minimum shock losses. In this line, a high-fidelity total pressure loss model has been developed in order to delineate an accurate loss budgeting. The numerical simulations in this research include realistic inlet boundary conditions directly extracted directly from a complete hydrogen-air RDE simulation performed in previous studies at the VKI. Initial URANS simulation has been conducted on the whole 2D unwrapped stator annulus with the main purpose of studying the effects of the inlet unsteadiness on a novel unstarting mechanism due to bow shock coalescence. Subsequently, a further 3D URANS simulation campaign was realized to assess unsteady performance of the full supersonic stage to highlight detailed stator and rotor field as well as the interactions between them.

Presenting Author: Bayindir H. Saracoglu von Karman Institute for Fluid Dynamics

Presenting Author Biography: Dr. Bayindir Saracoglu graduated from Mechanical Engineering Department of Boğaziçi University, Istanbul, Turkiye in 2004. He obtained his Master of Science degree in Mechanical Engineering from the same University in 2008. He graduated from Research Master Program of von Karman Institute for Fluid Dynamics (VKI), Belgium in 2008. He was a member of doctoral program of the VKI between July 2008 and July 2012. He has completed Wright State University PhD in Engineering Program in Ohio, USA in July 2012. He currently works as a Research Expert on Propulsion at the von Karman Institute. He has been involved in several European and international research projects. He has unique expertise in ramjet and scramjet engines, detonation based propulsion cycles, measurement techniques, flow visualizations, advanced data processing, high fidelity numerical simulations of confined supersonic flows, active and passive flow control techniques, novel propulsion concepts, flow in turbomachinery and high-speed external flows. He has authored more than 80 technical papers and 2 patents.

Authors:

Davide Visconti von Karman Institute for Fluid Dynamics
Bayindir H. Saracoglu von Karman Institute for Fluid Dynamics