Pre-LaFloDeS II

Important results from the project

The purpose of this project was to get closer to a more realistic flight condition than the transition studies previously conducted. The goals of the project have been to gain knowledge about how screws and rivets affect the transition from laminar to turbulent flow in more detail, and to study adaptive active flow control. Through analysis of experiments and numerical calculations, both purpose and objectives have been fulfilled in the project.

Expected long term effects

For the natural laminar flow with microstructures on the wing surface, which simulate screws and rivets, experiments show that there are global instabilities for relatively high structures and that the sensitivity is high for free-flow turbulence in the flow behind the microstructures. For the active flow control, positive effects have been demonstrated in both tests and CFD calculations. The understanding of surface imperfections such as screws and rivets and the potential of active flow control can, from an environmental perspective, lead to better design of future aircraft.

Approach and implementation

Analyzes of experiments conducted in Sweden and Brazil have been developed for both natural laminar flow and active flow control. Furthermore, numerical simulations of transition processes have been performed with different microstructures on the wing surface for studies of natural laminar flow and in addition, the effect of the active flow control has been studied to see the potential potential for reducing the aerodynamic drag.