Influence of casing contouring on flutter boundaries of a jet engine fan

Autor: Eberhard Nicke, F. di Mare, Derek Micallef, David Engelmann, Senad Iseni, Ronald Mailach
Rok vydání: 2018
Předmět:
Zdroj: CEAS Aeronautical Journal. 10:805-815
ISSN: 1869-5590
1869-5582
DOI: 10.1007/s13272-018-0351-y
Popis: This paper describes a detailed flutter analysis of fan casing contour modifications on a scaled high-speed fan to investigate the influence and effect on flutter boundaries. The flutter analysis focusses on discrete selected members from a previous multidisciplinary study of an automated aero-acoustic optimization with respect to the overall engine performance. The aerodynamic baseline performance of the high-bypass ratio fan is validated with measured rig data using Reynolds-averaged Navier–Stokes (RANS) CFD simulations. Flutter stability predictions are based on the energy method in traveling wave and influence the coefficient formulation using a multi-passage fan assembly in a wide engine operating range. Transonic stall flutter occurs for the first bending mode of blade vibration at part speed, where a few design members show an increased stabilizing aeroelastic behavior especially at approach flight condition. In contrast to that, the results indicate a destabilizing flutter stability effect for certain casing designs at cruise speed related to higher mass flows near choke, which is identified as a transonic unstalled flutter type. Aerodynamic key parameters for the flutter onset mechanism have proved to be the shock/boundary layer interactions in tip region of the fan suction side, which leads to flow separation. A second mechanism is driven by the additional blade vibration in combination with the interaction of shock and tip clearance flow as well as the incoming flow.
Databáze: OpenAIRE
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