Effect of Natural Ventilation of Internal Boundary Layer on the Flow Characterisitis of a Supersonic air-Intake

Ritu, Kanchan Dubey (2010) Effect of Natural Ventilation of Internal Boundary Layer on the Flow Characterisitis of a Supersonic air-Intake. Project Report. National Aerospace Laboratories, Bangalore.

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    Abstract

    Experiments were carried out on the model of an isolated supersonic air-intake to study the effect of natural ventilation of the internal boundary layer on the overall pressure distribution, total pressure recovery, intake buzz oscillations and surfaceflow patterns in the Mach number range of 2 to 3 at design and off-design conditions. The intake was stared in supercritical condition with benign back-pressure condition; the back-pressure was gradually increased using a butterfly valve driven by a PCcontrolled stepper motor. The tests were carried out at the 0.3m supersonic blowdown wind tunnel at the Experimental Aerodynamics Division, NAL, Bangalore. The results show that with ventilation, significant improvement in the total pressure recovery occurs at all back-pressure conditions, with the optimum vent gap of 1.6mm indicating improvement in the pressure recovery efficiency from about 60% to 90% at Mach 3; improvement was observed at Mach 2 also, though of reduced magnitude. Schlieren visualizations suggest a clear delay in the occurrence of critical condition of the intake. Ventilation created a stable oblique shock at the intake cowl lip, in contrast to the bow-wave without ventilation, indicating reduced spillage and improved pressure recovery of th e entry flow. Image analyses of video pictures suggest a limit-cycle oscillation of the oblique shock just past the critical region. Numerical simulation for some selected cases was carried out with and without ventilation using a CFD code FLUENT. Reasonable agreement with the experimental data was observed.

    Item Type: Proj.Doc/Technical Report (Project Report)
    Uncontrolled Keywords: Supersonic air intakes, Buzz, Boundary layer control
    Subjects: ENGINEERING > Mechanical Engineering
    Division/Department: National Trisonic Aerodynamic Facilities
    Depositing User: Ms Indrani V
    Date Deposited: 09 Apr 2012 11:32
    Last Modified: 09 Apr 2012 11:32
    URI: http://nal-ir.nal.res.in/id/eprint/10422

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