Planar shock cylindrical focusing by a perfect-gas lens

P. E. Dimotakis*, R. Samtaney

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

53 Scopus citations

Abstract

We document a gas lensing technique that generates a converging shock wave in a two-dimensional wedge geometry. A successful design must satisfy three criteria at the contact point between the gas lens and the wedge leading edge to minimize nonlinear reflected and other wave effects. The result is a single-point solution in a multidimensional parameter space. The gas lens shape is computed using shock-polar analysis for regular refraction of the incident shock at the gas lens interface. For the range of parameters investigated, the required gas-lens interface is closely matched by an ellipse or hyperbola. Nonlinear Euler simulations confirm the analysis and that the transmitted shock is circular. As the converging transmitted shock propagates down the wedge, its shape remains nearly uniform with less than 0.1% peak departures from a perfect circular cylinder segment. Departure from the design criteria leads to converging shocks that depart from the required shape. The sensitivity to incident shock Mach number, as well as the qualitative effects of the presence of boundary layers are also discussed.

Original languageEnglish (US)
Article number031705
JournalPhysics of Fluids
Volume18
Issue number3
DOIs
StatePublished - Mar 2006
Externally publishedYes

Bibliographical note

Funding Information:
The authors would like to acknowledge discussions with Paul Miller, Omar Hurricane, and Karnig Mikaelian of the Lawrence Livermore National Laboratory (LLNL), as well as discussions and exchanges with Hans Hornung, Dale Pullin, Dan Meiron, Amy Lam, and David Hill of Caltech. This work was performed under the auspices of the U.S. Department of Energy by the U.C. LLNL, under Contract No. W-7405-Eng-48, DOE/Caltech ASC/ASAP Subcontract No. B341492.

Keywords

  • Aerodynamics
  • Boundary layers
  • Flow simulation
  • Mach number
  • Shock waves

ASJC Scopus subject areas

  • Computational Mechanics
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering
  • Fluid Flow and Transfer Processes

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