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Proposing Institution

Department for Numerical Fluid Dynamics, TU Berlin
Project Manager

Dr. Julius Reiss
Müller-Breslau-Straße 8
10623 Berlin
The processes in Pulse Detonation Engines (PDEs) need to be investigated in detail in order to use its higher energy efficiency with respect to conventional turbomachinery designs. The increase in efficiency is due to the fact that the unburned fuel ahead of the reaction front is not ejected from the combustion chamber before burning. The PDE technology works on high pressure combustion regimes, which are characterize by the rapidly compression of the fuel-oxidizer mixture by a detonation wave. No expansion of the unburned mixture takes place and the combustion process is approximately isochoric. Another further improvement in the performance can be achieved by the combustion ignition type. The direct ignition of a detonation implies large energy gradients, which makes the approach unattractive. A better solution is to ignite a deflagration by a low energy input and accelerate it till a transition to detonation occurs. One of the main goals of this study is therefore the understanding of the mechanism responsible for triggering the Deflagration-to-Detonation Transition (DDT) in the combustion chamber. Only the understanding of the underlying physical phenomena involved in the DDT will lead to a stable cyclic process, feasible for PDEs. For this purpose numerical methods will be applied to investigate the fluid dynamics behaviour and its optimization potential. The numerical approach includes unsteady and highly spatially resolved Direct Numerical Simulations (DNS) of the Navier-Stokes Equations (NSE) with elementary combustionmodels. As a part of the project an optimal ignition will be sought to determine a fast and reliable transition in short length con figurations. To perform the optimization the use of the adjoint NSE is planned, which implies the development of an adjoint combustion model within theframework of this work. In the preliminary stage the geometry under study is a 2-D channel and will be extended to a 3-D pipe. Fluidic obstacles will be used in the configuration set-up in order to implement stable cycles. Their influence in the process of transition will be specially investigated. The final aim of this research is to create a DDT in a controlled and reproducible manner for the use in PDEs.

Impressum, Conny Wendler