15th European Conference on Turbomachinery Fluid dynamics & Thermodynamics

Paper ID:


Main Topic:

Combustor Interaction



Noraiz Mushtaq - Politecnico di Milano, Italy
Paolo Gaetani - Politecnico di Milano, Italy


Rotating detonation engines (RDE) are characterized by a thermodynamic cycle with an efficiency gain up to 15% at medium pressure ratios with respect to systems based on the conventional Joule-Brayton cycle. Multiple turbine designs can be considered and this work focuses on the supersonic inlet configuration. The unstarting of a supersonic inlet turbine is an undesirable condition since a normal shock wave is more dissipative than a bow-shock wave and the flow becomes subsonic downstream. To avoid this phenomenon, the best practice recommends maintaining the maximum contraction ratio above the self-started limit; nonetheless a complex unstarting mechanism was observed when a collective bow shock is generated. First a thorough explanation is given on how a collective bow shock is formed ahead of the blade row and why this leads to the unstarting of a supersonic channel. An unsteady simulation with transient from a started condition was performed to find the unstarting limit and then further simulations were carried out to understand the different flow behavior for conditions below or above this limit. Parametric analyses were performed to find the starting limit curve at various Mach number, metal angle, incidence angle, leading-edge shape and pitch to leading-edge thickness ratio. Finally, a detailed description is presented on the further restrictions induced by this new limit on the stator and rotor design.


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