UNSTARTING PHENOMENA IN THE DESIGN OF A SUPERSONIC INLET TURBINE

Abstract

A supersonic inlet turbine is an attractive solution to extract power from the highly fluctuating and supersonic flow delivered by a rotating detonation combustion chamber. To avoid unstarting in a supersonic inlet turbine, the best practice recommends maintaining the maximum contraction ratio above the self-started limit; nonetheless a complex unstarting mechanism was observed when a collective shock is generated. First, a thorough explanation is given on how a collective shock is formed ahead of the blade row and why this leads to the unstarting of a supersonic channel. Then, parametric analyses were carried out to evaluate the effect of Mach number, geometric and incidence angles on the collective shock unstarting limit. Finally, it is presented a comprehensive overview of all supersonic inlet turbine design limits, and design guidelines are updated in view of the further restrictions introduced by this additional constraint.