Presenter: Andrew Tagg
Authors: Andrew Tagg
Faculty Advisor: Andrew Ning
Institution: Brigham Young University
Viscous drag calculations are essential in aerodynamic analysis of aircraft. Unfortunately, a completely accurate model of viscous drag is very computationally expensive because it involves complex boundary layer equations and turbulence modeling. Including varying geometries and multirotor propulsion systems further complicates the calculation. The driving question behind this work is as follows: How can we effectively model the viscous effects on an aircraft without expending too many resources in an effort to solve the boundary layer equations? This paper will present an approach to the problem that is less expensive, but still provides a relatively accurate calculation. The method in question can be used for any geometry defined by cartesian coordinates, and will be able to analyze complex rotor-wing interactions. This project involves the development of a published package in the Julia language that accepts an arbitrary surface mesh, and a velocity field. It then returns a calculation of viscous drag based on those two arguments. The package will first determine stagnation points based on the directions of local velocity vectors, and then define streamlines that start from those stagnation points. Then it will find Reynolds numbers for each space along the streamlines, calculate the viscous drag at each space, and integrate to approximate total viscous drag. The result is an inexpensive, mid-fidelity model of viscous drag that can be used for general aircraft as well as eVTOL applications. When necessary, the same method can easily be implemented in higher fidelity models as well.