Methods of determination of aerodynamic loads at flight in continuous turbulence

Abstract

This paper investigates the loads which acting on the elastic high aspect ratio wing of a cargo aircraft flying in continuous turbulence. According to the requirements of CS-25, gusts that are normal to the flight path and uniform at spanwise are considered. Random gusts at continuous turbulence are described by the spectral density (PSD) of gusts suggested by Karman.The simulation of the flow around the calculated model aircraft are performed by the methods of computational aerodynamics: dipole lattice method (DLM), high order panel method (Panel), dipole lattice and constant pressure method (DLM/CPM), vortex frame method (VFM). Flow is accepted as quasi-stationary or non-stationary. The elastic mass model of the aircraft is described by beam. The discrepancies between the results of the load calculations from the continuous turbulence on the aircraft elastic wing are determined.The results show that taking into account the effects of non-stationary aerodynamics results in somewhat lower values of loads on the aircraft structure: up to 2% in the root sections of the wing and up to 5% in the end sections. The largest difference is observed using the dipole lattice method and the smallest one is in the panel method. The magnitude of the load increase from turbulence is almost the same for all the considered methods. Its main difference is observed when determining loads in horizontal flight, where the lowest values are obtained when using DLM / CPM.The main results are presented in graphical and tabular form.