Application of Sensitivity Analysis to the Redesign of OGV’s

This paper discusses the application of sensitivity analysis to the redesign of outlet guide vanes (OGV’s) in an aircraft high bypass turbofan engine. The redesign is aimed at reducing the interaction of the pylon induced pressure field with the OGV’s and fan blades. The redesign is performed using (a) a linear perturbation CFD analysis and (b) a minimisation of the pressure mismatch integral by using a Newton method. In method (a) the sensitivity of the upstream flow field to changes in blade geometry is acquired from the linear perturbation CFD analysis, while in method (b) it is calculated by perturbing the blade geometry and finite differencing the resulting flow fields. The redesigned OGV row reduces the pressure variation at the fan trailing edge by 86%. An OGV row with only 3 different blade shapes is designed using the above method and is found to suppress the pressure perturbation by more than 73%. Results from these calculations are presented and discussed.