Jan Deeken

Combustion efficiency sensitivity studies of the API injector concept

Since a few years DLR Lampoldshausen has been engaged in the development of a new injection concept for cryogenic liquid propellant rocket engines. This concept bases on the injection of the liquid oxygen through a large number of simple tubes while the entire hydrogen is injected through the porous face plate.3, 4 The key feature of the API concept is the independency of the atomization, vaporization, mixing and combustion performance of initial injection conditions such as velocity ratio, momentum fluxratio, Weber number or other non-dimensional parameters which are generally deemed important. This statement will be supported by data optained with a 50mm subscale combustion chamber. The influence of the velocity ratio at injection will be shown through a variation of the propellant mixture ratio and/or the chamber pressure.

Design and testing of a porous injector head for transpiration cooled combustion chambers

The present publication describes the design and testing of a porous injector head which was specifically designed towards an application in a transpiration cooled combustion chamber as a part of the German Research Network ”Propulsion 2010”. In order to determine comparable performance data, this injector head was tested with a conventional water cooled 80 mm diameter combustion chamber. This assembly was tested at the test bench P8 at the DLR Institute of Space Propulsion in Lampoldshausen. The resulting data was compared to test data which was obtained by using a conventional 42-element coaxial injector head and an identical combustion chamber configuration. During the operation of the new porous injector head serious instability problems were encountered.

Investigation of the API-Injection Concept in a LOX/LH2 Combustion Chamber at GG/PB Operation Conditions

A proper design of an injection system for liquid propellant rocket engines (LPRE) has to ensure a homogenous mixture of the injected propellants, which should result in a stable and highly efficient combustion process. In addition to combustion stability and efficiency it determines the propellant pressure losses upstream of the combustion chamber as well as the combustion chamber size required for a complete reaction of the injected propellants. This publication deals with the application of a new injection concept to operating conditions typically found in fuel rich LOX/H2 gas-generator (GG) or pre-burner (PB) combustion chambers. This injection concept was developed at the German Aerospace Center’s Institute of Space Propulsion and was named “Advanced Porous Injector” (API). Its feasibility has been demonstrated for operating conditions typical for main combustion chamber (MCC) applications during various test campaigns. The injection conditions typical for GG or PB applications impose new challenges on the injection system. The test campaign reported here was performed using the propellant combination LOX/H2 with a hydrogen injection temperature of 50 K and an oxidizer to fuel ratios ranging from 1 to 0.6. The successful operation of an 80 mm diameter combustion chamber equipped with a porous injector head has been demonstrated for chamber pressures up to 330 bar.