Laser-absorption sensor suite for crank-angle-resolved, in situ measurements in the exhaust of a high-performance...

High-speed sensors are necessary to provide crank-angle-resolved data for the validation of computational models of high-performance internal combustion engines. To this end, a near-infrared laser-absorption sensor was developed for measurements of temperature and water (H₂O) mole fraction near the exhaust valves of such an engine. A spectroscopic database was assembled for the target transitions, and the database was expanded to include broadening and narrowing by carbon dioxide (CO₂). Sensor accuracy was validated in benchtop experiments at representative conditions. The sensor was deployed on a single-cylinder development engine during dynamometer testing. Engine exhaust dynamics were captured at a rate of 31 kHz, sufficient for crank-angle-resolved measurements up to 5200 RPM, with 2σ uncertainties of 5.1% and 5.8% in temperature and H₂O mole fraction, respectively. Together with simultaneously deployed carbon monoxide, carbon dioxide, and unburnt hydrocarbon sensors and a high-speed pressure transducer, the sensor developed in this work forms a comprehensive suite for characterizing the exhaust conditions of an internal combustion engine.