Numerical Simulations of Shock-Wave Propagation in Turbofan Intakes
Simulation numérique de la propagation d'ondes de choc dans une manche d'entrée d'air de turboréacteur
Résumé
Several approaches of N-wave generation and propagation have been studied during the past forty years, but most advanced semi-analytical models still consider geometrical simplifications. In this paper numerical simulations based on the Euler solver of a CFD code dedicated to the capture of shocks generated by turbofans in transonic conditions are investigated. The main objective is to take into account actual inlet geometry and realistic convection flow associated with nonlinear propagation. Regular and non-regular shock waves are directly injected in a plane close to the fan and propagated through the inlet. The initial shock description near the fan is provided either by a steady RANS computation or by experiment, or else from an analytical modeling. Unsteady Euler calculations on suited acoustic grids are favorably compared to analytical solutions on simplified (quasi-2D) cases, and significant 3D effects are highlighted on realistic configurations. First application to a Snecma turbofan demonstrator using both test bed measurements and RANS solution as input data show that the present numerical approach is able to accurately assess the buzz saw noise spectrum measured in the intake.