Design of a Highly Efficient Low-Noise Fan for Ultra-High Bypass Engines

Abstract

In order to achieve an environmental-friendly engine i.e. with more efficiency and less noise emission, a geared ultra-high bypass ratio fan test rig has been designed within the EU-funded project SILENCE®. Engine cycle requirements were untypical in terms of mass flow rate, pressure ratio and BPR. In order to reach the desired mass flow rate and simultaneously to avoid a strong interaction of the shocks with the boundary layer an S-shape leading edged rotor with forward sweep close to casing has been designed. Specific blade numbers for rotor and stator has been used to minimize the rotor-stator interaction noise. For the same purpose a backward swept bypass stator has been designed. There are two stators in the core duct in order to bring the flow to zero swirl which is a necessity for test rig measurements. The main design loop includes blade shape and the flow path optimization as well as the computation of stress distribution in all blades and the rotor disc. The fan is being manufactured from titanium because of its specific aeroelastic properties and stators are made of steel. The rig is scheduled to be tested in 2006 for its aerodynamic and aeroacoustic performance.