A parallel, object-oriented framework for unsteady free-wake analysis of multi-rotor/wing systems

• Published in: Computers & fluids 2021-01, Vol.215, p.104788, Article 104788
• Main Authors: Joseph, Cibin, Mohan, Ranjith
• Format: Article
• Language: English
• Subjects: Aerodynamics; Distributed propulsion; Free wake analysis; Lattice skew parameter; Many body problem; Object-oriented programming; Roofline analysis; Rotary wing aircraft; Solvers; Unsteady vortex lattice method; Workstations
• ISSN: 0045-7930; 1879-0747
• DOI: 10.1016/j.compfluid.2020.104788

•Object-oriented vortex-based method for simulating multi-rotor aircraft.•Novel lattice-skew parameter for monitoring magnitude of instabilities.•Applications of vortex methods in distributed propulsion and electric urban mobility.•Unsteady vortex lattice method runs in cubic time with timesteps. The development, validation, and applications of an object-oriented free-wake solver for multi-rotor and fixed-wing systems are outlined here. Advantages of utilizing the object-oriented philosophy for modeling the multi-rotor/wing free-wake problem are described. To explore the feasibility of utilizing conventional desktop workstations, the vortex lattice methodology’s time complexity is examined as an evolving n-body problem and the advantage gained from employing wake roll up models is demonstrated. Modifications in typical formulae to leverage features of multi-core systems and improvements in computational performance obtained from these modifications are illustrated using a roofline analysis. The free-wake solver incorporating these optimizations is then employed—after extensive validation—to simulate a distributed propulsion aircraft and a multi-rotor urban mobility vehicle. The paper also proposes a novel lattice skew parameter for monitoring instabilities in wake solutions commonly observed in rotorcraft free-wake analysis.