Computational fluid dynamic studies on helicopter main-rotor-hub assembly unsteady wake

Abstract

The helicopter tail shake phenomenon is an area of great concern to helicopter manufacturers as it adversely affects the overall performance and handling qualities of the helicopter, and the comfort of its occupants. This study aims to gain information of the flow field that governs helicopter tail shake phenomenon which has frequently puzzled the aerodynamicists. Using Computational Fluid Dynamic (CFD) approach, the Multiple Reference Frames (MRF) method was applied to simulate the helicopter’s main-rotor-hub assembly rotation. In this study, the aerodynamic flow field was computed using the Reynolds- Averaged Navier-Stokes (RANS) equations. As the induced wake, which consequently causing tail to shake differs with the rpm of main-rotor-hub assembly, this preliminary numerical investigation was performed ranging from rpm of 0 to 900, with intervals of 300 rpm. A rotor-hub-fairing which covers partly the main-rotor-hub assembly was also employed to examine its effect on the wake unsteadiness. Results tell the rotation of main-rotor- hub assembly and pylon do significantly influencing the flow unsteadiness.