Semester

Fall

Date of Graduation

2006

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

James Smith.

Abstract

The separation of gases is required for a variety of applications such as purification for industrial processes, natural gas production, isotope formation, etc. Gas separation is a costly expenditure for businesses, so new and improved methods are being continuously investigated. Separation techniques related to the method in this thesis are diffusion separators such as mechanical centrifuges, vortexes and the use of shock waves to cause the separation based on the molecular weight of the different gases. These methods and others are constantly being investigated and improved to increase their effectiveness.;The purpose of this thesis was to determine if the design of a supersonic gas separator in Figure 1 can be modeled using a numerical computer program to accurately model the device. This thesis will strictly be concerned with the gas dynamics aspects of this device and not the diffusive separation aspects. The design was modeled using a CFD (computational fluid dynamics) program called Fluent which was then compared to analytic results to verify the Fluent results. The program was run using air and the pressure differences of the gas were varied by adjusting the inlet and outlet pressures in the model. This was done to achieve different speeds of the flow which is the main force driving the gas separation. The physical effects such as gas speed, temperature, and pressure in the device are computed numerically by Fluent. These results are then compared to those from an analytic model previous work in literature to gain a better understanding of the effects of the device.*.;The results from the Fluent cases correlated to the analytic results. When the downstream pressure was dropped below 30% of the stagnation pressure, the supersonic expansion fan was able to attach to the first skimmer and began the formation of a supersonic beam. This caused the skimmer to not act as a sonic throat when the supersonic inner core of the barrel shock that was formed in the first chamber maintained its velocity through the skimmer throat. The formation of a supersonic beam at lower pressure ratios corresponds to results found in literature, and the converging-diverging nozzle aspects of the device at higher pressure ratios also corresponds to compressible gas theory.;*Please refer to dissertation for diagrams.

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