Laser Ignition in a Micro Combustor

Ignition in cryogenic rocket engines is a critical phase during which small anomalies in the sequence timing can lead to the destruction of the chamber. The understanding of ignition processes taking place in such devices is scientifically very challenging and a key-point in terms of technical design. The M3 test rig operated at the German Space Center (DLR) is a rocket-like micro-combustor dedicated to the characterization of primary ignition phenomena of a single coaxial injector. In this test facility, combustion is initiated with a laser which provides the required synchronization accuracy for optical diagnostics. After describing the experimental setup, this paper presents the temporal evolution of the flow and the flame after the laser pulse, recorded by high-speed visualization techniques. In addition to experimental results, a numerical calculation based on the Large Eddy Simulation approach of the laser ignition is carried out. A detailed comparison of experimental and numerical data provides interesting insights on the ignition scenario.