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Vortex formation in a shock-accelerated gas induced by particle seeding
Peter Vorobieff1, Michael Anderson, Joseph Conroy
1Department of Mechanical Engineering, The University of New Mexico, New Mexico 87131, USA.
Physical Review Letters
|June 4, 2011
Summary
A shock wave passing through seeded air creates an instability, forming counterrotating vortices due to the interaction between air and particles. This multiphase flow phenomenon is driven by shock acceleration and differential phase velocities.
Area of Science:
- Fluid dynamics
- Multiphase flow physics
- Shock wave phenomena
Background:
- Planar shock waves interacting with two-phase media can exhibit complex instabilities.
- Nonuniform seeding of particles or droplets in a gas influences flow behavior.
- Understanding shock-induced instabilities is crucial for various engineering applications.
Purpose of the Study:
- To investigate the formation of an instability in a shock-accelerated two-phase gas-particle flow.
- To elucidate the physical mechanism behind vortex formation in such flows.
- To analyze the role of seeding concentration and relative velocity in instability development.
Main Methods:
- Utilizing a shock tube to generate a planar shock wave.
- Introducing nonuniform seeding of small particles or droplets via vertical air jet injection.
- Observing flow evolution in the plane normal to the shock and jet axis.
Main Results:
- Formation of two counterrotating vortices downstream of the shock passage.
- Instability mechanism linked to shock acceleration causing relative motion between gas and particles.
- Entrainment of the gas phase by the particle phase, dependent on seeding concentration and leading to vortex generation.
Conclusions:
- The observed instability is a unique multiphase flow phenomenon.
- Relative velocity between phases, induced by shock acceleration, is the primary driver for vortex formation.
- Seeding concentration critically influences the entrainment process and subsequent flow structures.
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