Liquid rocket engines play a central role for space transportation systems tovgenerate the needed thrust. An alternative to established ignition systems is the laser ignition concept, where a laser pulse is focussed into the combustion chamber to generate a plasma volume which initiates the combustion process. The goal of this work is the experimental investigation of the laserinduced ignition process in cryogenic liquid rocket engines. First, integration options of laser ignition systems into rocket engines were formalized. Then, the energy deposition within the propellants was analyzed analytically and numerically to determine the available energy for ignition. Afterwards, the minimum pulse energies needed for reliable ignition were determined experimentally in a thruster at the test bench M3.1 at the DLR Institute of Space Propulsion in Lampoldshausen. The identified minimum pulse energies of 0,8 to 33,2 mJ varied significantly in function of the ignition location and pressure conditions before propellant injection. No ignition was achieved with the maximum laser energy for vacuum conditions at ignition locations close to the injector faceplate which can be attributed to the high fuel velocities after injection into the chamber and limited mixing at this location. The low pulse energies needed for ignition allow future investigation of fibre-based transportation of the laser pulses. Based on these test results, experiments have been realized to investigate into the effects of propellant sequence variations onto the ignition success. These tests were carried out at the research and technology test bench P8 using a subscale combustor with LOX/GH2 and LOX/GCH4. As a result, intervals of propellant injection parameter like mixture ratio, momentum flux ratio and fuel injection characteristics were derived to ensure reliable ignition. The corresponding intervals are larger for LOX/GH2 compared to LOX/GCH4. In particular for LOX/GCH4, the methane injection characteristics were found to be critical for the flame spreading and anchoring. Additionally, a propellant sequencing with short, oxygen rich pre-flow was identified as favorable for reliable ignition and low ignition overpressures. By these results, this thesis contributes to the application scenarios, sequencing strategies of laser-induced ignition for cryogenic liquid rocket engines. At the same time, it opens perspectives for fibre-based laser ignition systems for space transportation systems.


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    Titel :

    Experimentelle Untersuchung der laserinduzierten Zündung von kryogenen Flüssigkeitsraketenbrennkammern


    Weitere Titelangaben:

    Experimental investigation of the laser-induced ignition of cryogenic liquid rocket combustors


    Beteiligte:
    Börner, Michael (Autor:in) / Oschwald, Michael (Akademische:r Betreuer:in) / Pfitzner, Michael (Akademische:r Betreuer:in)

    Erscheinungsdatum :

    01.01.2022


    Format / Umfang :

    1 Online-Ressource : Illustrationen, Diagramme pages


    Anmerkungen:

    Dissertation, RWTH Aachen University, 2022; Köln : Deutsches Zentrum für Luft- und Raumfahrt, Forschungsbericht / DLR, Deutsches Zentrum für Luft- und Raumfahrt 2022-29, 1 Online-Ressource : Illustrationen, Diagramme (2022). = Dissertation, RWTH Aachen University, 2022



    Medientyp :

    Sonstige


    Format :

    Elektronische Ressource


    Sprache :

    Deutsch