Separation Control for Aeroengine Intakes, Part 2: High-Speed Investigations

This paper documents the second part of an investigation into how fluidic control can be used to reduce separation-induced total pressure nonuniformity in an aeroengine intake. Flow conditions typical for an intake operating in a pure 90 deg crosswind are recreated in a laboratory-scale experiment. The lip rig concept, discussed in Part 1 (Wakelam, C. T., Hynes, T. P., Hodson, H. P., Evans, S. W., and Chanez, P., "Separation Control for Aeroengine Intakes Part 1: Low-Speed Investigation of Control Strategies," Journal of Propulsion and Power, Vol. 28, No. 4, 2012, pp. 758-765), has been developed for application in a high-speed study. The sector rig exhibits the same behaviors as a three-dimensional intake: low-speed separation hysteresis, attached flow bucket at moderate fan-face Mach numbers, and shock-induced separation. The flow control method of vortex generator jets is applied to reduce the negative effects of this shock-induced separation. Measurements of static pressure distribution show that separation is delayed to a higher fan-face Mach number when fluidic control is applied. Total pressure measurements in the fan-face plane show that distortion can be reduced over the full range of separated cases. A nonintrusive method of inferring the state of the flow in the intake, which could be used in a fully active control system, is also presented. [PUBLICATION ABSTRACT]