On porous liquid propellant rocket engine injectors

Progress in Propulsion Physics

Haidn

et al. 2011

The e¨ect of throttling on combustion e©ciency and stability of a porous injector head has been investigated for the LOx/H 2 propellant combination. Several pressure ramps (PR) ranging from 30 to 100 bar have been used so that a broad range of possible chamber pressures was covered. Regarding the design pressure of 80 bar, this was equivalent to a throttling range of 37.5% to 125%. The hydrogen injection temperature was varied between 50 and 105 K. The oxygen injection temperature was about 115 ± 5 K. All tests were performed at the P8 test bench using a 50-millimeter diameter modular combustion chamber. The combustion e©ciency at a hydrogen injection temperature of 105 K varied between 97.5% and 99% and was nearly independent of pressure. For hydrogen at 50 K, the combustion e©ciency increased with chamber pressure and ranged from 94% to 97%. The combustion roughness at 50 K was higher than for the 105-kelvin test cases.

Section: Api Approachmentioning

confidence: 99%

Combustion efficiency of a porous injector during throttling of a LOx/H₂combustion chamber

Progress in Propulsion Physics

Haidn

et al. 2011

“…To address these disadvantages of the coaxial injector principle, a novel injection concept for gas/liquid propellant combinations has been investigated over the last decade, both experimentally and numerically [4][5][6][7][8][9][10][11]. It aims at combining the favorable combustion performance and stability of a conventional coaxial injector with a drastically reduced manufacturing complexity.…”

mentioning

confidence: 99%

Propellant Atomization for Porous Injectors

Journal of Propulsion and Power

Oschwald

et al. 2019

Porous injectors represent an alternative injection concept to coaxial injectors for rocket engine applications using gas/liquid propellant combinations such as liquid oxygen (LOX)/hydrogen (H 2 ). This paper summarizes the main design features of porous injectors and proposes a mechanism of atomization for porous injectors that is considerably different to the atomization mechanism for coaxial injectors. The results of hot-fire test campaigns are presented, in which several parameters relevant to the injection process were varied: the injection velocities and momentum fluxes, the combustion chamber Mach number at the beginning of the nozzle contraction, and the LOX injector diameter. All hot-fire tests were conducted at P8 test facility for high pressure combustion research at the DLR site of Lampoldshausen with 50-mm-diameter combustion chambers operated with LOX∕H 2 at sub-and supercritical chamber pressures between 30 and 100 bar. The results presented here are supporting the proposed mechanism of atomization and allow derivation of some general design guidelines for porous injectors.

“…Optical investigations of a porous injector by Lux et al [6] indicated an attached and stable §ame for hydrogen to oxygen velocity ratios of up to 2.11 at hydrogen injection temperatures of about 135 K. The velocity ratio for the unstable test runs with the original API80-168 injector head ranged between 0.3 and 0.35, due to the lower hydrogen injection velocities at lower injection temperature. The absolute value of the velocity di¨erence was below 8 m/s.…”

Section: Introductionmentioning

confidence: 99%

“…Former investigations indicated an onset of this main atomization and mixing zone at an axial distance from the face plate of approximately 30 mm. Figure 1a shows OH images obtained with a porous injector with ¦ve LOx injector elements at sub-, trans-, and supercritical conditions [6]. Four injector elements were arranged around a central injector element.…”

Section: Introductionmentioning

confidence: 99%

Impact of injection distribution on cryogenic rocket engine stability

Progress in Propulsion Physics

Schlechtriem

et al. 2013

The present publication addresses the actions taken to stabilize the combustion chamber assembly using a porous injector head described in a former publication and the test campaign during which the success of these measures was demonstrated. The ¦rst part deals with the nature of the reported combustion instability. A phenomenological explanation for its occurrence is presented and supported by experimental data. As a measure to counter this instability, two approaches were taken. First, a hydrogen cooled baªe segment, and second, a modi¦cation of the injection distribution of the injector head with respect to the presumed cause of the instability. While the baªe segment did not prove to be successful, the test runs with the modi¦ed injection pattern demonstrated the stable operation of the 80-millimeter porous injector head over the whole range of operating conditions from 50 to 90 bar at hydrogen injection temperatures as low as 45 K.