Semester

Summer

Date of Graduation

2020

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

V’yacheslav Akkerman

Committee Member

Ismail Celik

Committee Member

Terence Musho

Abstract

Modeling of a turbulent two-phase gaseous-solid flow still faces challenges. The present study is devoted to two-phase flow in an annular pipe (hollow cylinder) operating at an elevated pressure of 15 bar and moderate Reynolds numbers of circa 6 x 103. The influence of the various factors – such as the particle loading, the interaction between the phases, and turbulent dispersion – on the flow dynamics is systematically studied by means of the computational simulation employing the ANSYS FLUENT commercial package. To be specific, particle loading with a volumetric fraction of 1.2 % is defined as high particle loading, while the flow with a volumetric fraction of 0.13 % is referred to as low particle loading. In particular, seven various cases for a gas-solid phase flow are investigated:

1) Pure gas flow;

2) Low particle loading two-phase flow with one-way coupling and with turbulence dispersion;

3) Low particle loading two-phase flow with two-way coupling but without turbulence dispersion;

4) Low particle loading two-phase flow with two-way coupling and with turbulence dispersion;

5) High particle loading two-phase flow with one-way coupling and with turbulence dispersion;

6) High particle loading two-phase flow with two-way coupling but without turbulence dispersion;

7) High particle loading two-phase flow with two-way coupling and with turbulence dispersion.

The boundary layer was found to be growing without fluctuations of the turbulent kinetic energy (TKE) for Cases 1, 2, and 5 above. For Case 4, the TKE fluctuations have been identified though appeared not as substantial as in Cases 6 and 7. The author attributes such a difference in the fluctuations to the particle loading. In addition, the onset and development of the flow instability have been observed at a random axial distance in Cases 4, 6, and 7. Such instability is presumably attributed to the two-way coupling with turbulence dispersion in a flow. It is concluded that the particle loading, one-way, or two-way coupling between the phases, and the turbulence dispersion models significantly influence the flow dynamics. The present computational results inspire to perform experimental verification and validation of the simulations, so the simulation results can subsequently be used for the design analysis.

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