Numerical modelling of unsteady flow in a twin side-by-side intake system

Abstract

AbstractThe unsteady flowfield in a twin side-by-side intake arrangement arising as a result of a surge in one of the engines has been studied numerically by solving the Euler equations. Unsteadiness was introduced by prescribing a pressure disturbance at the exit plane of one of the intakes. The two cases considered correspond to static ground-running of the engines and a flight Mach number of 0.6 with a single rapidly increasing exit plane pressure disturbance representative of a pop surge. The amplitude of the imposed pressure disturbance varied between 100% and 200% of the mean exit static pressure. In the cases considered, the results indicate that static pressure attenuation of the propagating hammer shock occurs upstream of the intake entry plane, resulting in a relatively weak rarefaction wave travelling down the adjacent intake. No evidence of increased dynamic flow distortion likely to lead to a complementary surge in the adjacent engine was observed. These conclusions have been confirmed by available test data thus demonstrating the value of CFD techniques for modelling complex unsteady transient flow phenomena of this type.