Linear stability analysis of particle-laden planar jet in the dilute suspension limit

TL;DR

This study analyzes how particles influence the stability of a planar jet flow in dilute suspensions, revealing that particle size, density, and loading significantly affect flow stability and mode behavior.

Contribution

It provides a detailed linear stability analysis of particle-laden planar jets, highlighting the effects of particle Stokes number, density ratio, and non-uniform loading on flow stability.

Findings

Low Stokes number particles increase flow instability.

Intermediate Stokes numbers stabilize the flow, damping unstable modes.

Non-uniform loading introduces new instability modes.

Abstract

Particle laden flows are commonly seen in many industrial applications such as fluidized beds in process industry, air laden with abrasive particles in abrasive machining and particle laden plumes in chemical industries. In the present work, we perform local analysis of a particle laden planar jet in the dilute suspension regime. Unladen parallel planar jets have been extensive studied using normal modes and is shown to have two unstable modes namely sinuous and varicose modes. Sinuous modes are found to be more unstable compared to the varicose modes. In the present study, we investigate the effect of particles on the stability of planar jets. Addition of particles at low Stokes numbers (St) (fine particles) results in higher growth rates than that of the unladen jet. In the intermediate Stokes number regime, addition of particles have a stabilizing effect on both the sinuous and the varicose modes. Interestingly for St~10, the unstable varicose mode is completely damped. Increasing the Stokes number by increasing the particle size, both sinuous and varicose modes show increasing growth rates, while increasing density ratio has a stabilizing effect on the flow. For non uniform particle loading, additional modes apart from the sinuous and varicose modes are observed. These modes suggests occurrence of compositional instability with an increased particle accumulation in the shear layer that is an order of magnitude higher compared to that of the sinuous and varicose modes.