Investigation of droplet ignition under microgravity conditions using laser-based techniques—an overview

Laser-based diagnostics like Laser Induced Fluorescence (LIF) and Particle Imaging Velocimetry are well established methods for combustion research under microgravity conditions. Especially the investigation of the ignition behaviour of single droplets and droplet arrays is important for future developments of internal combustion engines and power plants. Novel developments of experimental components like an solid state laser source (Advanced disk laser, ADL) and a high pressure insert (European High Pressure Insert, EHPI) for use in NASA's Combustion Integrated Rack are described. Innovative measuring methods to observe in a quantitative way the ignition process of droplets using LIF of formaldehyde and infrared absorption in carbon monoxide induced by quantum cascade lasers are presented.