Spatio-temporal characteristics of flow field and aerodynamic excitation force in rotating detonation engine turbine

Rotating detonation turbine engines are anticipated to bring transformative improvements to the performance of aeroengines. However, the exit flow field of the rotating detonation combustor significantly affects the operation of the downstream turbine. Addressing the operating characteristics of the turbine under rotating detonation environments, a moving shock wave model is established to reconstruct the unsteady inlet conditions of the turbine. Numerical simulations are conducted on the turbine under these extreme working conditions, analyzing the evolution patterns and characteristics of the internal flow field and aerodynamic excitation. The results indicate that the turbine is subjected to strong nonlinear incoming flow perturbations, with inlet parameters exhibiting severe temporal variations. The interaction between the moving shock waves and the turbine generates complex wave system structures. The wave structures upstream and downstream of the turbine are similar, but under different propagation modes, the interaction forms specific shock systems in turbine passages. The combined effect of the severe temporal variations of the incoming conditions and the evolution of the wave systems leads to temporal fluctuations in the turbine's attack angle, with the attack angle of guide vane changing by >20° and a significant reduction in the flow deflection within the rotor. In the detonation environment, the moving shock waves and their induced shock systems are the primary sources of the pressure oscillations in the turbine passage and the aerodynamic excitations on the rotor blade. Although the aerodynamic excitation on the blade surface increases, the circumferential force on the blades decreases by nearly 60 %, and the pressure oscillation level of the blades increases by >15 times compared to the baseline conditions.