Unsteady flow through a sharp-edged single-hole orifice placed in a pipe

Orifice plates or flow restrictions are key components used in industry for flow measurement and control. They find application in gas and liquid circuits of, e.g., lithography machines, nuclear power plants and aerospace propulsion systems [1]. They are used typically either for measuring flow-rate or to introduce a pressure drop for purposes of flow balancing. It is widely acknowledged in literature that the turbulent, unsteady nature of the flow through an orifice can be a source of structural vibration

Force generation and wing deformation characteristics of a flapping-wing micro air vehicle 'DelFly II' in hovering flight

The study investigates the aerodynamic performance and the relation between wing deformation and unsteady force generation of a flapping-wing micro air vehicle in hovering flight configuration. Different experiments were performed where fluid forces were acquired with a force sensor, while the three-dimensional wing deformation was measured with a stereo-vision system. In these measurements, time-resolved power consumption and flapping-wing kinematics were also obtained under both in-air and in-vacuum conditions. Comparison of the results for different flapping frequencies reveals different wing kinematics and deformation characteristics. The high flapping frequency case produces higher forces throughout the complete flapping cycle. Moreover, a phase difference occurs in the variation of the forces, such that the low flapping frequency case precedes the high frequency case. A similar phase lag is observed in the temporal evolution of the wing deformation characteristics, suggesting that there is a direct link between the two phenomena. A considerable camber formation occurs during stroke reversals, which is mainly determined by the stiffener orientation. The wing with the thinner surface membrane displays very similar characteristics to the baseline wing, which implies the dominance of the stiffeners in terms of providing rigidity to the wing. Wing span has a significant effect on the aerodynamic efficiency such that increasing the span length by 4 cm results in a 6% enhancement in the cycle-averaged X-force to power consumption ratio compared to the standard DelFly II wings with a span length of 28 cm

Unsteady flow through a sharp-edged single-hole orifice placed in a pipe

Orifice plates or flow restrictions are key components used in industry for flow measurement and control. They find application in gas and liquid circuits of, e.g., lithography machines, nuclear power plants and aerospace propulsion systems [1]. They are used typically either for measuring flow-rate or to introduce a pressure drop for purposes of flow balancing. It is widely acknowledged in literature that the turbulent, unsteady nature of the flow through an orifice can be a source of structural vibration [Aerodynamic

The DelFly: Design, Aerodynamics, and Artificial intelligence of a Flapping Wing Robot

This book introduces the topics most relevant to autonomously flying flapping wing robots: flapping-wing design, aerodynamics, and artificial intelligence. Readers can explore these topics in the context of the "Delfly", a flapping wing robot designed at Delft University in The Netherlands. How are tiny fruit flies able to lift their weight, avoid obstacles and predators, and find food or shelter? The first step in emulating this is the creation of a micro flapping wing robot that flies by itself. The challenges are considerable: the design and aerodynamics of flapping wings are still active areas of scientific research, whilst artificial intelligence is subject to extreme limitations deriving from the few sensors and minimal processing onboard. This book conveys the essential insights that lie behind success such as the DelFly Micro and the DelFly Explorer. The DelFly Micro, with its 3.07 grams and 10 cm wing span, is still the smallest flapping wing MAV in the world carrying a camera, whilst the DelFly Explorer is the world's first flapping wing MAV that is able to fly completely autonomously in unknown environments. The DelFly project started in 2005 and ever since has served as inspiration, not only to many scientific flapping wing studies, but also the design of flapping wing toys. The combination of introductions to relevant fields, practical insights and scientific experiments from the DelFly project make this book a must-read for all flapping wing enthusiasts, be they students, researchers, or engineers