Author ORCID Identifier

https://orcid.org/0000-0003-0728-4061

Semester

Fall

Date of Graduation

2022

Document Type

Thesis

Degree Type

MS

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Vyacheslav Akkerman

Committee Co-Chair

Mohsen Ayoobi

Committee Member

Mohsen Ayoobi

Committee Member

Osama Mukdadi

Abstract

Technological progress in the last decades facilitated the development of integrated microsystem devices, including electrical and mechanical components for micro-electro-mechanical systems (MEMS). Such systems necessitate an external power supply, but typical batteries yet have some unavoidable limitations. To address this problem, numerous studies have been conducted to develop alternatives powered by micro combustion – in order to effectively utilize the high-density energy of hydrocarbon fuels. Such a global need has resulted in much more attention devoted to the combustion-based micro-power generation systems. However, to better understand the typical combustion characteristics in such microscale systems, design and performance restrictions need to be further examined. A notable research step in this direction is undertaken within the frame of the present thesis, where the behavior of a premixed methane-air flame in a quartz microreactor of diameter 2.3 mm, with a wall temperature externally controlled by a McKenna-style flat-flame burner fueled by a hydrogen-air mixture, is computationally studied. A premixed methane-air mixture is supplied to this microreactor at various inlet velocities in the range from 0.1 m/s to 0.6 m/s. In addition, various equivalence ratios in the range 0.6 ≤ �� ≤ 1.4 are considered and further investigated at two inlet velocities of 0.2 m/s and 0.4 m/s. Such a combination of equivalence ratios and inlet velocities provides insights into the impact of the equivalence ratio on both the stable and unstable flames. The present simulation results are validated by the prior experimental data as well as by other similar studies in the literature, with good agreement observed. The present work provides in-depth insights into a variety of phenomena such as ignition, flame propagation, flames with repetitive extinctions and ignitions (FREI) and flame stabilization. In particular, the ignition time and location, the flame span, and the FREI-related characteristics are scrutinized. The present work also provides a solid basis to predict the flame behavior under various conditions and aid in acquiring knowledge of the combustion dynamics for many practical combustors.

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