Computational aerodynamics and aeroacoustics of steady and unsteady airfoils envisioning the application in novel concepts of urban air mobility

Abstract

Recent technologies of urban air mobility have been more inclined towards the use of rotors as a form of propulsion. In this context, new configurations of vertical take-off and landing vehicles (VTOL) were developed as an alternative for mobility in dense urban centers, and also in the context of product delivery. During this phase of development, there is concern about the level of greenhouse gas emissions, so that most aircraft concepts have employed electric motors (eVTOL). Another aspect of paramount importance in the design of eVTOLs is the reduction of aerodynamic noise generated by the rotors. Aircraft certification depends on standards that restrict noise levels and, currently, there is an effort by certifying authorities to establish standards for eVTOLs. Reducing aircraft noise is a complex task, since aeroacoustic sources are intrinsically related to the vehicle aerodynamics and the flow turbulence. Therefore, understanding the flow mechanisms responsible for noise generation is essential for designing quieter air vehicles. In this work, high-fidelity numerical simulation techniques will be applied to study unsteady flows past wings and blades aiming applications in rotor configurations. The flows of interest will be simulated by solving: 1) the compressible Navier-Stokes equations, and 2) a commercial tool that employs the lattice-Boltzmann method (LBM). Data-driven techniques for flow analysis, capable of providing modal decompositions of transitional and turbulent flows, will be applied to analyze unsteady flows and their acoustic sources. Moreover, acoustic analogy formulations such as the Flowcs Williams & Hawkings equation will be used to predict the noise generated by rotors. Finally, correlations will be presented between the turbulent coherent structures and the acoustic field.