In the hypersonic regime scramjet engines offer a great potential for future propulsion systems of space transportation applications. The intake of a scramjet engine compresses the incoming air for an efficient combustion cycle while aiming to produce minimum drag and heat load. One feature of the scramjet intakes flow field is the shock wave/boundary layer interaction (SWBLI) which causes high peak heat loads and affects the direction as well as the load of the aerodynamic force. The current understanding of SWBLIs allows the prediction of the aerodynamics and the heat load of a scramjet intake flow field with occurring SWBLI, if the size of the interaction is known. Since this size could so far not be estimated and varies during flight of a space launcher, the aim of this study was to provide a correlation for the separation size and to describe the variation of this size for the different flow similarity parameters. The approach of this study employed experimental testing as well as numerical simulations whereby the latter utilized the performed experiments during this study as well as experiments conducted by other investigators. Through such additional test cases, the number of covered similarity parameters could be increased so that the experiments and numerical simulations provided a good validation data base for the developed analytically based model of the SWBLI size. The hypersonic shock tunnel TH2 produced the desired hypersonic free stream conditions at different total temperatures to test the employed models which were a double ramp configuration and a scramjet intake. Both permitted the investigation of different leading edge radii and of different wall temperatures which were provided by the installed electric heating. The double ramp configuration was a redesign of a previous model and addressed two-dimensional SWBLIs in the midspan of the model. To study three-dimensional effects on the SWBLIs and their influence on the scramjet intake's flow field, at first the scramjet intake model had to be developed. This development included the improvement of the model heating technique which allowed wall pressure measurements during experiments with wall temperatures up to 1000 K. Regarding the model heating technique, two constraints had to be considered. First, for wall pressure measurements the employed transducers had to be placed as close as possible to the heated model surface. The enhanced thermal insulation was the outcome of the developed sandwich construction resulting in maximum temperature gradients of 875 K/cm within the model. The SWBLI simulations were conducted with laminar, transitional and turbulent shear layer behaviour so that the experimental and numerical data set covered following influences on the SWBLI: Reynolds number, Mach number, total temperature, boundary layer state (laminar, transitional, turbulent), wall temperature, leading edge bluntness, side flow and, side wall installation. To describe the extent of the SWBLI, an analytically based model of the SWBLI was developed based on the momentum equation and employing several simplifications. All mentioned influences on the SWBLI were analysed based on physical reasoning with the developed analytically based model. The prediction of the separation length with the analytically based model showed good agreement with the experimental and numerical results whereby some limitations remain.


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    Titel :

    Investigation of the shock wave/boundary layer interaction of scramjet intake flows


    Beteiligte:


    Erscheinungsdatum :

    2010


    Format / Umfang :

    198 Seiten, Bilder, Tabellen, 108 Quellen




    Medientyp :

    Hochschulschrift


    Format :

    Print


    Sprache :

    Englisch