한국전산유체공학회:학술대회논문집

Korean Society of Computational Fluids Engineering (한국전산유체공학회)
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Study of the unsteady pressure oscillations induced by rectangular cavities in a supersonic flow field

  • Krishnan L. (Department of Aerospace Engineering, Indian Institute of Technology) ;
  • Ramakrishna M. (Department of Aerospace Engineering, Indian Institute of Technology) ;
  • Rajan S.C. (Department of Aerospace Engineering, Indian Institute of Technology)
  • Published : 2003.10.01
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Abstract

The complex, unsteady, self-sustained pressure oscillations induced by supersonic flow past a rectangular cavity is investigated using numerical simulations. The present numerical study is performed using a parallel, multiblock solver for the two-dimensional, compressible Navier­Stokes equations. Open cavities with length-to-depth (L / D) ratio in the range 0.5 - 3.3 are considered. This paper sheds light on the cavity physics, cavity oscillatory mechanism, and the organisation of vortical structures inside the cavity. The vortex shedding phenomenon, the shear layer impingement event at the aft wall and the movement of the acoustic/compression wave within the cavity are well predicted. The vortical structures· and the source of the acoustic disturbances are found to be located near the aft wall of the cavity. With the increase in the cavity length, strong recompression of the flow near the aft wall leading to a sudden jump in the cavity form drag is observed. The estimated cavity tones are in good agreement with the available semi­empirical relation. Multiple peaks are noticed in deep and long cavities. For the present free­stream Mach number 1.71, it is observed that around L/D=2.0, the cavity oscillatory mechanism changes from the transverse to longitudinal oscillatory mode. The effects of this transition on various fluid dynamics and acoustic properties are also discussed.

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