Tight Coupling Of Helicopter Airframe Including A Detailed Gearbox

Abstract

Until recently vibrations in helicopters could only be measured or anticipated with high levels of uncertainty. This changed when tools focused on coupling started to emerge offering to combine both state-of-the-art fluid and structural dynamics solutions. This enables to predict the fluid-structure-interactions in the design phase which is an invaluable addition to the engineer's toolbox. The presented work shows the results of a tightly coupled CSD-CFD simulation of a helicopter in forward flight. The trimming process is shown and followed by an analysis of energy distribution across the modes. The aerodynamic origins of the excitations are investigated based on the pressure distribution and vortex visualization. The influence of a detailed gearbox to the CSD model is estimated by comparing the results from two different CSD models.