An Investigation of the Wake and Vortex Formation of a Helicopter Rotor Blade

Abstract

Abstract Vortices are present in many engineering applications and are systematically generated by lifting surfaces. The vortex characteristics and the wake surrounding a helicopter rotor blade play an important role because they affect the flow physics surrounding the rotor blade. Therefore, an advanced mathematical and computational model of rotor wake and blade vortex gives a better understanding of the helicopter rotor dynamics. The strength of the vortex depends on the blade geometry, loading, and the aircraft’s operational state. A concentrated tip vortex line, an inboard trailing vortex sheet, and a shed vortex are accountable for aerodynamic airload generation. Among these, tip vortices have the maximum contribution and are formed by the rolling up of trailing vortices near the tip of the wing. In this study, tip vortex models are used to characterize the vortex core structure and prescribed wake models are utilized for analyzing the hovering flight. A Bo 105 composite, hingeless helicopter rotor blade is considered for the computational analysis. A fluid-structure interaction model is developed by coupling the finite element model of the rotor blade with a computational fluid dynamics model of the surrounding air to analyze the helicopter rotor blade dynamic response and to investigate vortex formation due to the fluid-structure interaction. The swirl velocity is minimum, and the axial velocity is maximum at the vortex center. The axial velocity decreases and swirl velocity increases with increasing the distance from the vortex center to the core radius.