Combustion Performance and Stability of a Porous Injector Compared with a State-of-the-Art Coaxial Injector

Kurzfassung

Injector behavior is of utmost importance for the performance and stability of liquid rocket engines. The injection system has to provide for a highly e�cient mixing and consequent chemical reaction of the propellants at a minimum chamber length. This article presents results of the experimental investigation for a new injection concept based on the application of porous materials. Porous Injectors represent a novel method of propellant injection in liquid propellant rocket engines. Earlier investigations revealed their high potential for gas/liquid propellant combi- nations, e.g. LOX/H2. The simple and low-cost manufacturing process and the good behavior during throttling of this class of injectors are signi�cant advantages compared with coaxial injectors commonly employed for this propellant combination. The present study focusses on a direct experimental comparison of a 168-element porous injector (API) with an injector head equipped with 19 state-of-the-art coaxial injector elements comparable to Ariane 5`s Vulcain II engine. The hot �re tests were conducted at the P8 test bench in Lampoldshausen. An 80 mm diameter calorimeter combustion chamber built by Airbus DS and identical measurement equipment were used with both injector head con�gurations, allowing a direct comparison of the test data. The combustion performance, stability, the wall heat �ux and the axial pressure pro�le were determined for operating conditions typical of the operating regime of Vulcain II. This included combustion chamber pressures of up to 115 bar and oxidizer to fuel mixture ratios of 5.4 up to 7.2.