Rotors play a major role in various applications including ventilation and propulsion systems such as in helicopters, drones, wind and gas turbines and many other cases. The present visualization shows instantaneous vortical structures (identified by the λ2 criterion) and highlights the complex flow structures emanating from a twisted drone rotor that is impulsively starting to rotate. Initially, a comparably weak starting vortex is formed as a result of lift generation and shed as a continuous vortex tube from the entire surface of the blade. It remains connected to the blade tip via the so-called tip vortex. Leading-edge separation occurs at span positions of high twist first, followed by wave-induced breakdown to turbulence along the whole wing span. This newly formed turbulence then sheds as small-scale vortices into the wake and eventually dissipates. Understanding the behaviour of these vortices from such complex blades and how they interact with the other blade is critical to design more efficient and potentially more silent propellers.The video shows two different view; one outside view of a steady observer, and an observer fixed to the rotating wing. In paritcular the second view provides an interesting view of the tip vortex and its swirl as the flow picks up speed.
This work is licensed under the Creative Commons Attribution-NonCommercial 4.0 International License. Any reuse must credit the author(s) and provide a link back to this page.