טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentAlexeev Alexander
SubjectTheoretical and Experimental Investigation on the Motion
of Small Particles in Resonance Tubes
DepartmentDepartment of Mechanical Engineering
Supervisors Professor Emeritus Chaim Gutfinger
Dr. Alexander Goldshtein


Abstract

Resonant gas oscillations in closed tubes and their effect on motion of small aerosol particles are investigated analytically, numerically and experimentally.

An analytical model is presented for one-dimensional inviscid gas oscillations about the first resonance frequency, where the gas flow is characterized by a shock wave traveling back and forth along the tube. The model is verified by comparison with a numerical solution, showing good agreement.

To account for heat and viscous effects, a two-dimensional numerical model of turbulent gas oscillations is developed and verified by comparison with experiments. Using the numerical model, turbulence and acoustic streaming at resonance are considered. A parametric study of resonant flow is performed in terms of the dimensionless tube parameters.

Using the flow models developed in this study, the motion of small aerosol particles within a resonance tube is investigated. It is found that particles drift along the tube due to periodic shock waves. The solutions indicate that the drift enhances aerosol agglomeration. The effects of the Saffman lift and thermophoretic forces on particles inside the boundary layer are also examined.

The time evolution of an aerosol affected by periodic shock waves is investigated experimentally and numerically. Favorable agreement is found between the experiments and the simulations, indicating that aerosol concentration changes mainly due to particle deposition, while the effect of agglomeration is relatively small. Particle deposition is caused by turbulent diffusion and the Saffman lift force.

The results of this study may be applied to the design of pollution control equipment.