Receptivity at the nozzle lip of under-expanded supersonic impinging jets

POSTER

Abstract

The receptivity of an under-expanded supersonic impinging jet flow at the sharp nozzle lip to acoustic impulse disturbances is investigated as a function of geometric and flow parameters. Receptivity is defined as the internalisation of an external disturbance into the initial condition that either initiates or sustains a vortical instability. In the case of under-expanded impinging jet flow subjected to an acoustic disturbance receptivity is located at the nozzle lip and amenable to an impulse response analysis using the linearised compressible three-dimensional Navier-Stokes equations. Under-expanded supersonic jets emanate from an infinite-lipped nozzle with a nozzle pressure ratio of 3.4 for two nozzle-to-wall distances (h) of 2 and 5 jet diameters have been studied. It is found that for both cases, acoustic disturbances located at angles greater than 80$^o$ from the jet centreline have the highest receptivity for all azimuthal mode-numbers, except the azimuthal mode-number 2 for h=5d. For h=5d there is also high receptivity to acoustic disturbances located at angles 15$^o$ - 50$^o$ from the jet centreline for all azimuthal mode-numbers.

*This research was funded by an Australian Research Council Discovery Project grant, which is gratefully acknowledged.

Authors

  • Shahram Karami

    • Monash University
    • LTRAC, Department of Mechanical and Aerospace Engineering , Monash University, Clayton Campus, Melbourne, VIC3800, Australia

  • Vassilis Theofilis

    • School of Engineering, University of Liverpool The Quadrangle, Brownlow Hill, L69 3GH, UK
    • University of Liverpool

  • Julio Soria

    • Department of Mechanical and Aerospace Engineering, Monash University (Clayton Campus), VIC 3800, Australia
    • LTRAC, Department of Mechanical and Aerospace Engineering, Monash University, Clayton 3800, Australia.
    • Monash University
    • Laboratory for Turbulence Research in Aerospace and Combustion, Department of Mechanical and Aerospace Engineering, Monash University
    • LTRAC, Department of Mechanical and Aerospace Engineering , Monash University, Clayton Campus, Melbourne, VIC3800, Australia
    • Lab. for Turbulence Research in Aerospace & Combustion, Department of Mechanical and Aerospace Engineering, Monash University, Melbourne, Australia
    • LTRAC, DMAE, Monash University