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Particle Kinetics of Gas-Solid Particle Mixtures

Citation

Haas, Roger Allison (1969) Particle Kinetics of Gas-Solid Particle Mixtures. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechTHESIS:03272017-145900980

Abstract

In this thesis the interaction of a normal gas dynamic shock wave with a gas containing a distribution of small solid spherical particles of two distinct radii, σ1 and σ2, is studied (1) to demonstrate that the methods of kinetic theory can be extended to treat solid particle collision phenomena in multidimensional gas-particle flows; (2) to elucidate some of the essential physical characteristics associated with particle-particle collision processes; and (3) to give some indication regarding the importance of particle collisions in particle-laden gas flows. It is assumed that upstream of the shock wave particles σ1 are uniformly distributed while particles σ2 are non-uniformly distributed parallel to the shock face and in much smaller numbers than particles σ1. Under these conditions the gas-particle σ1 flow downstream of the shock wave is very nearly one-dimensional and independent of the presence of particles σ2. The usual shock relaxation zone is established by the interaction of particles σ and the gas downstream of the shock wave. The collisional model pro- posed by Marble3 is then extended and used with a modified form of the mean free path method of kinetic theory to calculate the macroscopic distribution and velocity of particles σ2 as determined by the particle σ1- particle σ2 and particle σ2-gas interactions. Within the condition that the random velocity imparted to a particle σ2 by a collision is damped by its viscous interaction with the gas before it suffers another collision, the kinetic theory method established here may be extended to include more general particle-particle and particle-gas interaction laws than those used by Marble. However, the collisional model employed is particularly important because the criteria for its application are easy to establish and because it admits a wide class of physically interesting situations.

Within the restrictions of this collision model, it is possible to analyze the macroscopic motion of particles σ2 in three important limiting cases: (σ21)2 >> ⊥,(σ21)2 << ⊥ and (σ21)2 ~ ⊥. It is found that when (σ21)2 >> ⊥ there is essentially no redistribution of particles σ2 normal to the gas flow. The only effect of particle σ1 -particle σ2 encounters is a drag force acting to slow down particles σ2. When (σ21)2 << ⊥ it is found that particles σ2. may have many collisions during their passage through the shock relaxation zone. As a consequence there may be a substantial redistribution of particles σ2 downstream of the shock wave. The physical features of this process are studied in detail together with the range of validity of this diffusion model. The case (σ21)2 ~ ⊥ is analyzed under the condition particles σ2 have at most one collision during their passage through the shock relaxation zone. It is found that when the gas or particle σ1 density is low, the single collision effects may be important even when σ21 differs significantly from unity and the particles are not very small.

Under most conditions of practical significance, because there is invariably a distribution of particles sizes present in a dusty gas, the calculation of the particle distribution in the shock relaxation zone should account for the effects of particle-particle encounters. It is suggested that an experimental observation of particle size distribution in a shock relaxation zone can yield significant information on particle-particle and particle-gas interaction laws.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Engineering
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Engineering and Applied Science
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Marble, Frank E.
Thesis Committee:
  • Unknown, Unknown
Defense Date:26 May 1969
Funders:
Funding AgencyGrant Number
CaltechUNSPECIFIED
Robert O. Law FoundationUNSPECIFIED
Florence and Daniel Guggenheim FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Ford FoundationUNSPECIFIED
NSFUNSPECIFIED
Record Number:CaltechTHESIS:03272017-145900980
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:03272017-145900980
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10109
Collection:CaltechTHESIS
Deposited By: Benjamin Perez
Deposited On:28 Mar 2017 15:06
Last Modified:28 Mar 2017 15:06

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