Motivation
Wind energy has been gaining increasing popularity in recent years. This is partly because its production results in zero emission and therefore meets the requirement of a future green energy system, and partly because the operational cost of wind farms has been dropping significantly in recent years that wind power exploitation has become increasingly cost-effective.
To increase the efficiency of wind exploitation, wind turbines have grown larger and larger. To put this into perspective, the state-of-the-art turbine up to date has a turbine blade that is longer than the gigantic Airbus A320. The increasingly large turbines produces noise that is significantly louder. This has become one of the main issues concerning further developing onshore wind farms. Among many components, aerofoil noise is the main noise source, and designing quieter turbine blades is the leading impetus for aerofoil aeroacoustic research.
Background
Aerofoil noise is complicated, with more than one physical sources. However, it is widely accepted that the acoustic emission due to the interaction between wind turbine blades and the turbulent boundary layers, commonly known as trailing-edge noise, is the main component of wind turbine noise. Research on this component has been an active front line of current aeroacoustic research. After extensive research, techniques to reduce trailing-edge noise with various performances have been developed but the physical mechanisms of their noise reduction effects remain to be further elucidated.
Current research
Here in our group we apply advanced mathematical methods such as the Wiener-Hopf method and Matched Asymptotic Expansion to model the essential physics of trailing-edge noise generation and its reduction using various techniques. These analytical investigations are also complemented by experiments conducted in state-of-the-art aeroacoustic wind tunnels.