The design of nacelle chine in large civil transport aircraft

This paper applies the methods of CFD simulation of fluid flow, which are validated by wind tunnel results, to analyze the influences of installation location of nacelle chine on the lift performance of landing configuration from the change of spatial vortices. The numerical simulation results show that because of the influences of nacelle and pylon, the end of slats and cuts of main wing left by the deflection of slats, will induce a series of vortices in high angle of attack (α), which could bring separation in the upper surface of main wing easily. The vortex induced by nacelle chine can depress these vortices and low speed region of flow field above the main wing behind nacelle so that the stalling α and maximum lift coefficient will be improved. Regarding the landing configuration in this paper, its stalling α and maximum lift coefficient are increased by 2° and 0.15 respectively by the installation of nacelle chine. The vortex induced by nacelle chine will move downwards once the chine is put back or down, which leads to stronger restraint effects to other vortices and lower speed region. In order to increase the stalling α and maximum lift coefficient of landing configuration, both of the location and strength of vortex induced by nacelle chine must be taken into consideration in the design process. Because of some geometry restraints and adopting above investigation results, the location of nacelle chine is redesigned through the tradeoff study for the location and strength of space vortex. The CFD result shows that for the redesigned location of chine, geometry restraint is satisfied and the loss of maximum lift coefficient of landing configuration is less than 0.015, which still meets the design requests.