Turbofan engine intakes are designed to provide separation-free flow at the fan faceover a wide range of operating conditions. But at some off-design conditions, like at high flightspeeds and high angles of attack (Ao...Turbofan engine intakes are designed to provide separation-free flow at the fan faceover a wide range of operating conditions. But at some off-design conditions, like at high flightspeeds and high angles of attack (AoA), the aero engine intake may encounter flow separation.This boundary layer separation inside the nacelle inlet of an aircraft engine can lead to a largenumber of undesirable outcomes like reduction in fan efficiency, engine stall and high levels ofstress on the fan blades. Active flow control is a promising solution to reduce inlet boundarylayer separation and the associated fan-face flow distortion at such off-design conditions. Byblowing pressurized air into the intake near the separation point, the boundary layer is ener-gized and separation can be controlled. This study investigates the applicability of lip blowing,an active flow control technique, to control intake separation and flow distortion at the fan-face.First, intake separation was triggered in a 3D CFD model based on the NASA CommonResearch Model (CRM) using high AoA cases at cruise condition (Mach number 0.85, Massflow capture ratio w0.7) and the features of separated flow were analyzed. Thereafter, activeflow control was introduce to the intake in the form of two types of lip blowing, direct andpitched blowing. The efficacy of lip blowing at achieving separation control in an ultra highbypass ratio turbofan engine intake has been established through this study. The present paperalso examines the significance of blowing parameters like the type of blowing, blowing pres-sure ratio, and blowing slot dimension, at different angles of attack to identify the critical con-trol parameters. Our research successfully establishes proof of concept by demonstrating the feasibility of using lip blowing for separation control in aero-intakes, via numerical modelling.Furthermore, this study also provides crucial insights regarding the important variables to beconsidered for future experimental studies, and also for detailed studies covering a wider rangeof operating and blowing conditions.展开更多
文摘Turbofan engine intakes are designed to provide separation-free flow at the fan faceover a wide range of operating conditions. But at some off-design conditions, like at high flightspeeds and high angles of attack (AoA), the aero engine intake may encounter flow separation.This boundary layer separation inside the nacelle inlet of an aircraft engine can lead to a largenumber of undesirable outcomes like reduction in fan efficiency, engine stall and high levels ofstress on the fan blades. Active flow control is a promising solution to reduce inlet boundarylayer separation and the associated fan-face flow distortion at such off-design conditions. Byblowing pressurized air into the intake near the separation point, the boundary layer is ener-gized and separation can be controlled. This study investigates the applicability of lip blowing,an active flow control technique, to control intake separation and flow distortion at the fan-face.First, intake separation was triggered in a 3D CFD model based on the NASA CommonResearch Model (CRM) using high AoA cases at cruise condition (Mach number 0.85, Massflow capture ratio w0.7) and the features of separated flow were analyzed. Thereafter, activeflow control was introduce to the intake in the form of two types of lip blowing, direct andpitched blowing. The efficacy of lip blowing at achieving separation control in an ultra highbypass ratio turbofan engine intake has been established through this study. The present paperalso examines the significance of blowing parameters like the type of blowing, blowing pres-sure ratio, and blowing slot dimension, at different angles of attack to identify the critical con-trol parameters. Our research successfully establishes proof of concept by demonstrating the feasibility of using lip blowing for separation control in aero-intakes, via numerical modelling.Furthermore, this study also provides crucial insights regarding the important variables to beconsidered for future experimental studies, and also for detailed studies covering a wider rangeof operating and blowing conditions.
