Laser-Induced Incandescence Sensor for Soot Particle Size and Concentration

An instrument will be developed to measure the mass concentration and particle size of non-volatile particulate (nvPM) emissions exiting a nozzle into an altitude chamber for contrail condensation studies at NASA’s PAL and other facilities, with a potential future transition to onboard instrumentation for flight studies. Experimental studies will be conducted to optimize laser-induced incandescence for aircraft nvPM conditions at the 12-inch standoff distance required for the PAL facility, allowing it to be used for characterizing particles entering the chamber in situ, i.e., in their natural state. An existing numerical model will be improved to include relevant effects that will enable accurate interpretation of data from the in situ measurements. A calibration method for non-volatile soot mass and particle size will be developed that will anchor the method to accepted best practices and a detailed Phase II prototype design will be developed. Such measurements are needed to help determine which sustainable aviation fuels (SAFs) have the lowest sooting propensities, and thus would produce minimal contrails, which can trap heat in the Earth’s atmosphere. The proposed work directly addresses the objective of achieving cleaner, faster, and safer air travel in ways that minimize adverse impacts on the environment called out in NASA’s ARMD 2023 Strategic Implementation Plan. A significant market opportunity exists in research groups worldwide, including universities, government agencies, engine manufacturers, and industrial settings. A calibrated and validated in situ soot property diagnostic could replace extractive instruments in many applications, such as those concerning environmental control regulations for aircraft engine manufacturers, commercial airlines, industrial processing plants (i.e., stack monitors), commercial trucks, and automobiles.