Preliminary study on the effects of environmental conditions on Ionic Propulsion

Recently, the interest in a new type of propulsion for atmospheric flight has rapidly grown. Based on the acceleration of ionised air through a strong electric field, the ionic air-breathing thruster would bring multiple benefits in both environmental and economic terms. The absence of moving parts, low noise production, and no carbon emissions are just some advantages of this technology. However, the feasibility and application of these non-thermal plasma propulsion systems are still in their infancy, which is why the European IPROP project aims to explore their capabilities and improve their performances. Few, if any, studies in the literature describe how these thrusters are affected by external environmental conditions, such as temperature and humidity. In this context, the role of the von Karman Institute (VKI) is to study, inside a wind tunnel, how these two variables influence the performances of a prototype ion thruster. This thesis focuses, at least in the first part, on the study of the characterisation of the flow generated by the Low-speed Open-Loop wind tunnel L-7 at VKI in terms of temperature and humidity uniformity. Three different sensors for measuring the aforementioned variables were analysed to find out their static and dynamic response. These were then used both for a mapping of the temperature and humidity profile of the flow, and for the creation of a feedback control loop with the humidifier capable of supplying steam inside the wind tunnel to try to achieve a uniform and constant humidity profile. In the second part of the experimental campaign, efforts are dedicated to testing the applicability of the Particle Image Velocimetry (PIV) optical technique in the available facility. This technique was then used to calculate the drag, in absence of plasma, produced by an airfoil placed inside the test section, a crucial aspect in order to derive the actual thrust generated by the ionic air-breathing thruster in the future. In conclusion, this thesis is only the starting point of a larger project: further experimental testing must be carried out to really get to know how the performances of the thruster are affected by external environmental conditions.