Linear global stability of two incompressible coaxial jets

The preferred mode of incompressible jets: linear frequency response analysis

Linear Stability in an Ideal Incompressible Fluid

We give an explicit construction of approximate eigenfunctions for linearized Euler operator in dimensions two and three with periodic boundary conditions, and an estimate from below for its spectral bound in terms of an appropriate Lyapunov exponent. As a consequence, we prove that in dimension 2 the spectral and growth bounds for the corresponding group are equal. Therefore, the linear hydrod...

Transverse stability of relativistic two-component jets

Context. Astrophysical jets from various sources seem to be stratified, with a fast inner jet and a slower outer jet. As it is likely that the launching mechanism for each component is different, their interface will develop differential rotation, while the outer jet radius represents a second interface where disruptions may occur. Aims. We explore the stability of stratified, rotating, relativ...

Noise from Imperfectly Expanded Supersonic Coaxial Jets

Experiments have characterized the acoustics of axisymmetric high-speed jets at a variety of Mach numbers and velocities and at pressure-matched, overexpanded, and underexpanded conditions. The effect of an annular secondary  ow on noise emission was also investigated.The fully expanded jet velocity ranged from 630 to 920m/s and the fully expanded jet Mach number ranged from 1.27 to 1.75.The s...

"Lock-in" phenomenon in coaxial jets

Flow visualizations have been performed in order to study the vortex interactions in the near field of a coaxial jet configuration. Smoke has been injected in the outer stream and a continuous Argon Laser sheet has been used as a light source. Instantaneous pictures have been acquired at a rate of 1 kHz by means of DANTEC Nanosense MK1 camera. In order to remove the background noise the average...