Development of an airfoil-based passive volumetric air sampling and flow control system for fixed-wing UAS

Abstract

This study aims to develop a concept of a passive volumetric flow control system for gas sampling applications onboard fixed-wing UAS based on the pressure field around airfoils. The passive flow control system utilizes the aerodynamics of a UAS to create a vacuum pump effect that ensures constant gas sampling, which can be used to facilitate airborne aerosol and gas measurements. The pump effect is achieved by short-circuiting the pressure field’s minima and maxima points around an airfoil through pipes and 3D printed structures that could function both as a pump system and a gas measurement chamber. The design of this structurally integrated functionality brings many advantages for scientific applications, especially onboard small research UAS, which would dispense entirely with complex active pump systems, thus reducing weight and ensuring gas sampling at a constant volumetric flow rate independent of altitude and atmospheric variance. In favor of developing further applications, this paper outlines the development steps of the passive pump concept starting from the theory and numerical modeling of the effect to the implementation on board a fixed-wing UAS. Finally, possible improvements based on numerical models and flight measurements are discussed.