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Simulation of pulsating combustion under increased pressures
[1]- © SBL
The aim of the project is the depth investigation
of the processes of pulsating-detonative combustion. Essential for the
technical application of pulsating combustion is a fast and reliable
transition from deflagration to more efficient detonation (DDT). In
the experiment, a reliable DDT was found for a special geometry,
consisting of a chamber with a convergent-divergent nozzle. The
numerical simulation finds the DDT at the narrowest cross section as a
complex interaction of different phenomena, in particular flame
acceleration and shock focusing, which in turn is consistent with the
measured pressure data. The underlying phenomena are strongly
dependent on the speed of sound, heat release and characteristics of
the flame as well as the boundary and start conditions, thus on the
mixture properties and the operating conditions.
The
running processes will be examined in detail and the behavior under
changing operating conditions will be clarified, especially the
reliability of the DDT at high pressures and temperatures. The latter
is necessary for the design of the entire machine, since the
combustion chamber will work with pre-compressed air. Further insights
into the physical process should show possible improvements. In order
to depict the dependence of the process on different operating
conditions, the description of kinetics and gas properties must have
these dependencies. This is made possible by non-constant heat
capacities and a detailed chemistry (hydrogen). The actual DDT
mechanism will then simulated more accurately. The fine resolution of
the flame also makes it possible to more accurately simulate their
interaction with turbulence, thus improving the overall predictive
quality. Finally, the nitrogen oxide production will be
simulated.
Staff
Julius Reiss (Prof. Dr. rer. nat.)
Mathias Lemke (Dr.-Ing.)
Mario Sroka (M.Sc.)
Sergio Bengoechea (M.Sc.)
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