Starting characteristics of a rectangular supersonic air-intake with cowl deflection

Abstract

CR contraction ratio (A t /A c ) h cIntake capture height L overall length of model m e mass flow rate at diffuser exit (kg/s) m i capture mass flow rate (kg/s) P static pressure P b back pressure P bs sustainable back pressure P i free stream pressure P 0e total pressure at exit P 0i total pressure of free stream PE pressure ratio at exit (P b /P i ) θ 1 first ramp angle θ 2 second ramp angle θ 3 first diffuser angle θ 4 second diffuser angle θ c cowl deflection angle x distance from leading edge Y distance along the height of intake Y max maximum intake exit height TH ratio of throttled area at exit and throat (A e /A t ) FD flow distortion PR pressure recovery ABSTRACT Experimental and computational investigations have been made to obtain the details of the flow field of a supersonic air-intake with different cowl deflection angles and back pressures at the exit. The flow field obtained with an inviscid computation on the basic configuration, designed for Mach 2·2, shows starting behaviour whereas computation with k-ω turbulence model and experiments indicate unstart characteristics. Both experiments and computations indicate that provision of a small angle at the cowl tip leads to start of the same intake and also improves it's performance. Results obtained with cowl deflection shows a better performance in comparison to performance achieved with a basic intake and with a bleed of 2·8%. Sustainable back pressure could be obtained through the computations made at different back pressures for different cowl deflection angles. Overall results suggest that provision of small cowl deflection angle itself leads to improvement in performance achieved in comparison to a bleed of 2·8%, even with back pressure at the exit. NOMENCLATUREA t throat area A c capture area A e exit area

Hypersonic Intake Starting Characteristics–A CFD Validation Study

“…In order to bring out the condition at which the intake unstarting occurs, steady state simulations were also carried out for Mach 8,7,6,5,4,3.5,3.3,3.2 and 3 conditions respectively by varying the total pressure at inlet. Initially, all the simulations were carried out under adiabatic wall condition.…”

“…Das and Prasad 6 have conducted both experimental and numerical investigation of mixed compression intake flow field at Mach 2.2 with different cowl deflections and showed that small angle at the cowl lip leads to start of the intake and improve its performance. Experimental and numerical studies of Dirk, et al 7 demonstrate that bleed can reduce boundary layer separation and improve the inlet total pressure recovery.…”

Transonic flow instability in the entrance region of a channel with breaks of walls

“…7 and 8, we also consider an expanded computational domain in order to take into account a shock wave arising ahead of the lower wall. The configuration (1)-(3) will produce a flow pattern similar to a region downstream of oblique shocks generated by the compression wedge of a typical intake [3]. Its examination will contribute to the understanding of flow instability mechanisms in sophisticated intakes used in practice.…”

Investigation of Flow Field Around the Pointed Cowl Air Intake at Mach 2.0

“…They concluded that a definite increase in performance and flow quality by cowl bending and adopting bleed. Staring characteristics for intake with cowl deflection were also studied by Das and Prasad [2], concluded that cowl defection could be thought of an alternative to the bleeding for the intake model. Two dimensional simulations corresponding to different cowl bending studied by same authors [3] concluded that the increase in cowl deflection angle increased the performance for the intake model with pressurized exit and small deflection led to good pressure recovery.…”