Combustion diagnostics based on Diode Lasers have been in focus of research in recent years, due to the advances in optical technologies. Tunable Diode Laser Absorption Spectroscopy (TDLAS) has been employed for in-cylinder, nonintrusive, crank-angle resolved measurements in Internal Combustion (IC) engines. This thesis addresses a novel opto-electronic, multi-wavelength scheme for line-ofsight gas absorption measurements and tomographic imaging in IC engines. High temporal resolution measurements of H2O vapour using direct absorption spectroscopy (DAS), with external intensity modulation for phase sensitive detection, is implemented with Semiconductor Optical Amplifiers (SOAs). Using spectroscopic databases, two Near-IR overtone water transitions have been appropriately selected for ratiometric temperature compensation to enable concentration measurements, and an additional wavelength to account for nonabsorbing attenuation. A scanned-wavelength approach was used for laboratory evaluation of the new technique at 250 KS/s, and comparison with simulated absorption lines showed excellent accuracy and precision. Fixed-wavelength, Time-Division-Multiplexing (TDM) operation with SOAs as optical switching elements has also been demonstrated in the laboratory. A preliminary demonstration of the scheme on an optical engine has been presented with three projections continuously monitored at 150 KS/s during motored and fired engine operation. Valuable data for the system characterisation and future modifications and improvement have been obtained. Finally, tomographic imaging results of liquid and vapour phase fuel distribution in a motored IC engine are also presented.
|Date of Award||31 Dec 2014|
- The University of Manchester
|Supervisor||Krikor Ozanyan (Supervisor)|