For supersonic combustion with resulting positive engine thrust, the performance of the in-take is essential. That is why a combined investigation based on numerical analysis and experimental examination of SCRamjet intake geometries is undertaken within the Research Training Group (GRK) 1095/1. The numerical analysis is of great importance for the design of a well-suited hypersonic intake for the given flight trajectory. It was the purpose of this work to focus on the examination of laminar to turbulent transition for hypersonic boundary layers and its influence on the shock wave/boundary layer interaction for intake flows. First, this work presented a summary of the flow phenomena that have to be considered for hypersonic intake flows. It was followed by a general introduction of the research that has been done over the last decades in many different countries. For a better understanding of the conceptional design issues of SCRamjet intakes a review of existing and examined configu-rations was provided together with an evaluation of the advantages and disadvantages of the different designs. Second, the physical basis of laminar to turbulent transition was explained and the different reasons for this phenomenon were discussed in detail. Transition can be described in several different modes. The first mode is natural transition dominated by instability waves which are often referred to as Tollmien-Schlichting waves. The second mode is basically connected with the word By-pass transition. There are several phenomena that can cause this kind of transition process, for example cross-flow or wake impact on the boundary layer. After this a review of the possible numerical methods for predicting as well as modelling transition was given. Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) were described in general and their ability of predicting transition for macro three-dimensional industrial applications was pointed out. It was concluded that the only appropriate way of modelling transition for flow problems investigated within this project is using Reynolds-Averaged Navier-Stokes equations (RANS).
Numerical analysis of transition effects for SCRamjet intake flows
Numerische Analyse von Übergangeffekten bei Einlaufströmungen von Staustrahltriebwerken
2010
174 Seiten, Bilder, Tabellen, 149 Quellen
Theses
English
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