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Oskar J. Haidn

Other affiliations: German Aerospace Center
Bio: Oskar J. Haidn is an academic researcher from Technische Universität München. The author has contributed to research in topics: Combustion chamber & Combustion. The author has an hindex of 20, co-authored 189 publications receiving 1555 citations. Previous affiliations of Oskar J. Haidn include German Aerospace Center.


Papers
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TL;DR: In this paper, a 3D model of fuel flow in terms of the fuel's real properties and cracking reaction is built and validated through experiments to study the thermal behavior in the cracking reaction zone of regeneratively cooled scramjet cooling channels at different aspect ratios.

68 citations

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TL;DR: In this paper, the near injector combustion zone has been investigated in a coaxially injected liquid rocket engine (LRE) thrust chamber at steady state, high pressure conditions, and the influence of reduced pressure has been quantified based on LOx-spray evolution, assessment of flame emission intensity measurements and the efficiency and roughness of combustion.

67 citations

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TL;DR: In this paper, the effect of a recessed liquid oxygen tube in shear coaxial injection has been investigated experimentally using an optically accessible subscale rocket combustor operated at pressures between 40 and 60 bar.
Abstract: The effect of a recessed liquid oxygen tube in shear coaxial injection has been investigated experimentally using an optically accessible subscale rocket combustor operated at pressures between 40 and 60 bar. Different single-shear coaxial injectors have been used to inject liquid oxygen and methane at relevant operating conditions covering sub-, near-, and supercritical pressures with respect to the critical point of oxygen. Liquid oxygen was injected at 120 K and the injection temperature of gaseous methane was about 275 K. Detection of spontaneous OH and CH chemiluminescene has been performed to characterize the flame-anchoring zone near the liquid oxygen post tip. In addition, the influence of the injector geometry on the combustion roughness and stability has been investigated during steady-state operating points. An increased flame expansion was observed with a recessed injector element. At low momentum flux ratio, the pressure drop accross the injector increases with a recessed liquid oxygen tube compared with a flush tube. Furthermore, a recessed liquid oxygen tube led to be a smoother combustion in general; however, this configuration also led to additional resonant frequencies in the chamber acoustics.

56 citations

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TL;DR: In this paper, the authors used optical diagnostics to evaluate the near-injector region of a subscale liquid propellant rocket combustion chamber and found that spontaneous OH chemiluminescene has been detected to characterize the flame anchoring zone near the LOX post tip.
Abstract: Flame stabilization in the near-injector region of a subscale liquid propellant rocket combustion chamber has been investigated using optical diagnostics. Several different single shear coaxial injectors have been used to inject liquid oxygen (LOX) and methane at relevant operating conditions. Three main operating points cover the range of sub-, near-, and superciritical conditions with respect to the thermodynamic cirtical point of oxygen. Whereas liquid temperatures of about 270 K. Similar to previous investigations performed with LOX/H2 combustion, spontaneous OH chemiluminescene has been detected to characterize the flame anchoring zone near the LOX post tip. Theoretical considerations have indicated that the binary mixture of oxygen and methane shows and entirely different behaviour compared with the oxygen/hydrogen system. This is believed to have an influence on the spray evolution and mixing characteristics at supercritical conditions. The experimental investigation includes both the ignition transient a well as the steady-state operating points. It has been detected that the LOX/CH4 flame shows very similar characteristics in comparison with LOX/H2 flame at similar operating conditions. Critical flame stabilization at the startup transient has been found during all hot runs. At steady-state conditions, the influence of the injection parameters on the flame shape is comparable to previous LOX/Hydrogen investigations.

52 citations

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TL;DR: In this article, the results of velocity and temperature boundary-layer profile measurements made at the Dresden University of Technology were used to characterize the influence of foreign gas transpiration on skin friction and heat transfer.
Abstract: Blowing through the wall is one of the most efficient methods to influence the characteristics of a turbulent boundary layer such as heat transfer, skin friction, boundary-layer profiles, and flow separation. The most important technical application is to cool a permeable wall with a coolant mass flow through the wall, known as transpiration cooling. Designing transpiration-cooled devices requires the knowledge of empirical correlations for the calculation of skin friction and heat transfer in the case of blowing. The results of velocity and temperature boundary-layer profile measurements made at the Dresden University of Technology were used to characterize the influence of foreign gas transpiration on skin friction and heat transfer. Simple empirical correlations describing skin friction and heat transfer reduction as functions of the blowing ratio and especially the blowing gas properties were found. Further investigations deal with flow separation due to blowing, and a universal critical blowing parameter is defined. The empirical correlations have also been verified by means of a numerical calculating procedure. Measurements made at the German Aerospace Center in Lampoldshausen using an H2/O2 combustion chamber delivered experimental heat transfer results in the case of hot gas parameters according to practical applications.

51 citations


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Journal ArticleDOI
TL;DR: In this article, the initiation of turbulent non-premixed combustion of gaseous fuels through autoignition and through spark ignition is reviewed, motivated by the increasing relevance of these phenomena for new combustion technologies.

614 citations

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TL;DR: In this article, the authors extend past analyses of liquid-oxygen-hydrogen flames at supercritical pressure by providing quantitative results that characterize multicomponent diffusion processes in the flame zone of a shear-coaxial injector element.
Abstract: This paper extends past analyses of liquid-oxygen-hydrogen flames at supercritical pressure by providing quantitative results that characterize multicomponent diffusion processes in the flame zone of a shear-coaxial injector element. High-fidelity simulations, using both the large-eddy-simulation and direct-numerical-simulation techniques, have been performed using detailed treatments of thermodynamic, transport and chemical kinetics. Results are presented for a condition where oxygen is injected in a cryogenic state, at a subcritical temperature and supercritical pressure, and hydrogen is injected in a supercritical state. This condition has significant technical relevance in liquid-rocket engines but is not well understood. For this situation a diffusion dominated mode of combustion occurs in the presence of exceedingly large thermophysical property gradients. The flame anchors itself in the interfacial region of high shear that exists between the liquid-oxygen core and the annular hydrogen jet...

175 citations

Journal ArticleDOI

170 citations