Engineering Commons^™

A Study Of Nonlinear Combustion Instability, Eric J. Jacob

Doctoral Dissertations

Combustion instability (CI) has been persistent in all forms of propulsion since their inception. CI is characterized by pressure oscillations within the propulsion system. If even a small fraction of the dense energy within the system is converted to acoustic oscillations the system vibrations can be devastating. The coupling of combustion and fluid dynamic phenomena in a nonlinear system poses CI as a significant engineering challenge.

Drawing from previous analysis, second order acoustic energy models are taken to third order. Second order analysis predicts exponential growth. The addition of the third order terms capture the nonlinear acoustic phenomena (such as …

Tunable Diode Laser Absorption Spectroscopy Verification Analysis For Use In The Combustion Optimization And Analysis Laser Laboratory, Christina R. Serianne

Theses and Dissertations

The AFIT Combustion Optimization and Analysis Laser (COAL) laboratory has state-of-the-art laser diagnostic capability for combustion process. The research for this thesis served to enhance the COAL lab's capability. Currently, there are no known commercially available tunable diode lasers that produce Ultra-Violet radiation required for this analysis. Sum-frequency generation at 313.5 nm was utilized for high speed OH absorption and temperature measurements at a rate of 2kHz. The Tunable Diode Laser Absorption Spectroscopy system was validated by comparison with theoretical and well characterized experimental data by operating the system over a wide range of conditions for an H2 laminar flame …