| Abstract |
Aircraft manufacturers and airlines require lightweight and compact but highly efficient engines in order to realize an improvement in the thrust to-weight ratio and thus to save fuel. Space and weight of a compressor can be reduced within the passage of the compressor grid by enhancing the efficiency of one stage due to a stronger flow deflection. However, this leads to an increased risk of flow separation, which must be avoided for reasons of compressor stability. One approach to reduce separation areas is the active flow control. Previous research on active flow control in the compressor mainly focused on basic studies, determining the geometrical and aerodynamically optimal parameters for a successful flow control. The investigations were often carried out on large-scale and simplified experimental setups for the incompressible inflow Mach number range. In the present work, flow around a core engine fan stator (ESS) was investigated. The flow conditions of the studies of this thesis are based on the compressible transonic Mach number range of a conventional ESS. However, a stronger deflection and thus a higher loading was chosen as it is common in today’s engines, in order to investigate a possible efficiency increase by means of active flow control. The actuators were integrated into a linear compressor and operated at high subsonic flow conditions. The compressor stators were designed as CDA profiles and showed already strong three-dimensional flow phenomena at the design point. At the corner between blade and side wall pronounced corner separation was present due to the small aspect ratio of the blade. The possibilities to suppress the separated areas were investigated by means of active injection of compressed air. In order to fully exploit the benefits of active flow control, a closed loop control was established. |
