Laser-absorption sensor suite for crank-angle-resolved, in situ measurements in the exhaust of a high-performance internal combustion engine-I: temperature and H2O.

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.