Abstract 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.
Influence of casing contouring on flutter boundaries of a jet engine fan
CEAS Aeronautical Journal ; 10 , 3
2018
Aufsatz (Zeitschrift)
Englisch
Influence of casing contouring on flutter boundaries of a jet engine fan
Springer Verlag | 2018
|NTRS | 1989
|Control of Blade Flutter by Smart-Casing Treatment
AIAA | 2001
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