Design and testing of a hydrogen–oxygen pre-detonator for rotating detonation engines

Abstract Rotating Detonation Engines (RDEs) have the potential to significantly increase the performance of liquid-propellant rocket engines. Besides, they are also a promising improvement for gas turbine combustors. Therefore, there is a rapidly growing interest world-wide into this technology. One critical aspect of the experimental investigation of Rotating Detonation Combustors (RDCs) is the ignition process, because it has to ensure successful and repeatable ignition similar to conventional rocket combustion chambers and additionally also has a direct influence on the deflagration to detonation transition (DDT) in the RDC. One of the most common ignition and detonation initiation devices is a so-called pre-detonator. This is typically a tube, which is connected radially to the main RDC chamber and is designed in such a way that a detonation wave forms inside the pre-detonator tube and accesses the main RDC chamber radially. However, even though pre-detonators are widely used in RDC studies and are important for the detonation initiation process, publications that focus on pre-detonator design and testing are still quite rare. For that reason, this study summarizes the design and testing of a $$\hbox {H}_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>H</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> </mml:math> - $$\hbox {O}_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mtext>O</mml:mtext> <mml:mn>2</mml:mn> </mml:msub> </mml:math> pre-detonator. The presented results show that detonation waves are achieved with the given design and that the process is reproducible. Thus, DLR now has a simple pre-detonator operational, which can be used for future studies of rocket-type RDCs.