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Simultaneous observation of liquid phase distribution and flame front evolution during the ignition transient of a LOX/GH2-combustor

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Phenomena such as flame propagation, flame/spray interaction and flame stabilization during the transient ignition process in a cryogenic model rocket combustor are investigated on sub-millisecond time scale. Diagnostic techniques developed to characterize the stationary spray flame are applied to investigate the transient evolution of the LOX-spray and the flame front during the ignition process. Ignition is initiated by focusing a pulsed laser into the combustion chamber. Thus, ignition time as well as the position of ignition is well defined. This and the exact control of the delay between ignition and detection time allowed the observation of the evolution of the flame front. The distribution of the liquid oxygen phase and the velocity of LOX droplets and ligaments are determined by light sheet techniques using a double-pulsed laser system. Simultaneously the position of the flame front is measured by recording the spontaneous emission of the OH-radical. By varying the delay timet between ignition and detection in a series of test runs, the transient ignition phenomena has been investigated in the interval from 0 to 5 ms after ignition.

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d :

diameter of the LOX post

I :

intensity of OH emission

m :

mass flow

p :


v :

injection velocity

r :


t :

delay time

n :


c :

conditions in the combustion chamber

O2 :

(liquid) oxygen

H2 :



oxydator-fuel (in relations)


fuel-oxydator (in relations)


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Author information

Correspondence to V. Schmidt.

Additional information

Volker Schmidt: He received his diploma in 1996 from University of Jena (Germany). He joined DLR Lampoldshausen in 1996 and started to work on development and application of optical diagnostics to LOX/GH2 high-pressure combustion systems. His current research focus is basic research in ignition processes of LOX/GH2 rocket engines. He also continues intensive interest in the development of optical diagnostics in reactive two-phase flows (DTV, PIV).

Joachim Sender: He received his diploma in 1986 from University of Erlangen/Nuernberg (Germany) and worked at the Institute of Fluid Mechanics as a research fellow on Boundary Flows with Laser Doppler Anemometry until 1993. From 1994, he was a member of the Optical Diagnostics Group at DLR Lampoldshausen working on the application and development of optical diagnostic systems on supersonic flows and high-pressure combustion systems. Since 1996, he is head of the combustion chamber technologies group at DLR Lampoldshausen. His current research focus is the optimisation of cooling techniques in high-pressure combustion chambers and application of ceramic materials for chamber design.

Michael Oschwald: He received his Ph.D. degree in Physics in 1987 from Freiburg University and worked then as a research fellow (1987–1989) at the physics department of the University of Freiburg. He joined DLR Lampoldshausen and started to work on the development and application of optical diagnostics to supersonic flows and high-pressure combustion systems. Since 1998, he is a head of Rocket Propulsion at DLR Lampoldshausen. His current research interests are basic research in sprays and combustion under high-pressure conditions and rocket combustor technology. He has also continuing intensive interest in the development of optical diagnostics in reactive two phase flows (PIV, droplet sizing, CARS, Raman-scattering).

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Schmidt, V., Sender, J. & Oschwald, M. Simultaneous observation of liquid phase distribution and flame front evolution during the ignition transient of a LOX/GH2-combustor. J Vis 4, 365–372 (2001). https://doi.org/10.1007/BF03183899

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  • cryogenic
  • rocket engine
  • laser ignition
  • spontaneous emission
  • laser light sheet