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In recent decades huge effort has been placed on maintaining laminar boundary layers with respect to a number of applications. To a large extent this research concerned laminar wings, especially focusing on maintaining laminar boundary layer on the longest possible distance. The research of laminar boundary layer is inherently coupled with the investigations of instabilities leading to the laminar-turbulent transition. These research directions are still in progress. The existing knowledge, at its present stage of development, has been fully utilised in the project for the analysis of laminar boundary layer development and the following transition. It must be emphasized that TFAST objective was not to improve knowledge of laminar boundary layers and of transition. The general aim of TFAST was to avoid that the laminar boundary layer is penetrated by the shock wave. The benefits of having laminar boundary layer are so important that the transition should occur as late as possible. The sensitivity of the solution is calling for basic studies before the configurations closer to application may be investigated. It is necessary to carry out advanced experiments and accurate CFD work with the most advanced methods as LES and DNS. The topic of laminar/transitional/turbulent interaction with a shock wave is the most challenging problem in aeronautics, even more when unsteady interaction effects are to be treated. For these challenging tasks a consortium of the high quality was employed. It is not only the high scientific level and skills of the partners which is important but also the quality of partner’s cooperation and integration in the consortium. Due to the experience obtained from the consortium that was forming the UFAST project, and because the proposed research was based on the experience gained in UFAST, the core of the TFAST consortium consisted mainly of UFAST partners. Due to the industrial requirements and needs those partners being “only” observers in UFAST were employed as full partners in TFAST. Another “new” partner was DLR which carried out the experimental compressor and turbine cascade investigations. In summary one may conclude that the consortium is not only of the high European level, but that it has already a long tradition of successful collaboration. The main objective of the project was to study the effect of transition location on the structure of interaction between a shock wave and a boundary layer. Main question was how close the induced transition may be to the shock wave while still maintaining a typical turbulent character of the interaction. In other words, how far the laminar boundary layer may extend without changing the turbulent character of interaction. This question have been answered in WP-2 (i.e. in the basic type of the test section), and also in the flow cases characterising different applications in WP-3, WP-4 and WP-5.
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- Introduction—TFAST Overview
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