Optimisation of bypass fan outlet guide vanes

Abstract

In this paper we describe an approach for combined intake-fan-OGV-pylon interactions that can be used to optimise the OGV design. The mean flow through the fan and OGVs, which is taken to be locally two-dimensional, is prescribed for a datum configuration, and the intake distortion and pylon potential field are fed in, from upstream and downstream respectively, as small incident perturbations to a coupled fan-OGV actuator disk system. In order to optimise the OGVs we suppose that the vanes are recambered in blocks, using only a limited number of vane types. The extent of each block, and the degree of over or undercambering in each block, are used as variables within a standard multi-variable optimisation package. Following validation of the approach, results are presented for a number of cases which show, in particular, the importance of the back effect of the fan on the perturbation field at the OGV leading edge, and the relative benefits obtained by increasing the number of vane types.