Numerical investigation and design exploration on aerodynamic performance for stacked rotor

Abstract

A coaxial co-rotating (stacked) rotor can produce an improved aerodynamic efficiency compared to a coaxial counter-rotating rotor and a single-rotor with the same solidity. Since the aerodynamic performance of the stacked rotor highly depends on the relative positions of tip vortices and rotor blades, design parameters such as vertical spacing, phase angle, and pitch angle should be optimized for an operational condition. In this study, a numerical analysis through a high-order accurate Reynolds-Averaged Navier-Stokes solver was carried out to analyze the flowfields of stacked rotor configurations in a hovering condition. Design points were selected using the full factorial method with three design parameters. Exploring the wide design space revealed the full extent of performance that can be achieved through stacked rotor adjustment. The inflow and wake interference effects were turned out to be dominant factors in the aerodynamic performance of the stacked rotor system. The corresponding sectional thrust and power of each design point were modeled using a neural network. Finally, design exploration and optimization were conducted for aerodynamic efficiency.