Pylon and engine mounts performance driven structural topology optimization
Résumé
Engine deformations during operation are an increasing concern for engine performances. The tip-clearance, defined as the radial gap between the blade tip and the engine casing, can show small variations induced by aircraft maneuvers. These variations can produce increased tip leakage flow, secondary flows and vortex losses that can sensibly increase the engine trust specific fuel consumption (TSFC). In this paper the impact of pylon and nacelle design parameters on in-operation engine performance and overall mass is investigated for a turbofan engine. The structural behavior of the integrated engine will be simulated thanks to a linear finite element model that models the mechanical behavior of the engine under different load cases. Both rotor and stator are modelled to evaluate tip clearance deformations at different engine stages. In a first order approach these engine deformations are evaluated as the difference of radial displacements of superposed points of rotor and stator relative to blade tip. Then an in house performance engine model evaluates thrust specific consumption as a function of the tip clearances. In this paper, two structural optimization studies are conducted on a simple generic engine model in order investigate two different approaches to optimize the engine-pylon attachment. In the first study a classic statically determined engine mount system is considered and thrust link position and attachment points are made varying. In the second one, a topology optimization framework is developed and implemented to optimize from scratch the topology of the pylon-engine attachment design zone.