Application Research Of Transonic Compressor Rotor By Large-Eddy Simulation

The flow field in compressors is inherently unsteady. As one of the most importantcomponents of aerospace engine, the compressors play a important role in improving engineperformance, safety, stability. It is of great importance to understand the mechanism of unsteadyflow for the designing of compressors with high performances.The in-house large-eddy simulation code is applied in the current study, introduced by sixthorder precision WENOSYM scheme, compact central-difference scheme, dual-step implicitNewton iteration scheme and the technique of phase-lag. The main aim of the current paper is toshow the capability of the LES in performing the transition and the unsteady flow in transoniccompressor.Firstly,2-D Blasius similarity solution coupled with T-S waves as the inlet boundary layer isintroduced to study the process for laminar-to-turbulent transition in a spatially developingboundary layer. Simulation result exhibits the formation and evolution of hairpin vortex andmultiple vortex rings with four ring-like vortex, coupled with complex ejection/sweep movementsand high/low speed streaks.Secondly, the physical phenomenon of impinging shock wave/turbulent boundary layerinteraction is discussed with the recycling/rescaling method as the turbulent inflow conditions.The simulation indicated the occurrence of shock-induced boundary layer separation.Finally, three-dimensional steady and unsteady numerical simulations were carried out toanalyze the complicated flow in a1.5-stage transonic axial compressors. The steady computationcompared the difference of flow structures between two different compressor ratios. Thewake-mixing process between adjacent blade rows and the mechanism of passage shockinteractions with boundary layer in rotors are analyzed in detail in the unsteady simulation.Nonlinear interaction effects were significant at the transonic compressor, with very high levels ofunsteady loading occurring in the vane trailing edge region because of interactions with therotor-generated shock waves, eventually the vane trailing edge work failure because of high cyclefatigue.