IPER-MAN Innovative PERmeable Materials for Airfoil Noise reduction


Modern aerodynamics is responding to the world energy crisis with the creation of the largest machines on Earth.
Among many examples, large wings/blades are optimized to harvest energy from the wind (e.g. wind turbines) or to decrease fuel mass spent per payload (e.g. aircraft and propellers). Improving performance through upscaling comes with a huge increase of aeroacoustic noise, which directly affects the health of human population, as well as it obliges wind turbine manufacturers and airports to restrict the operating envelope of wind turbines and airplanes.
The research of this STW project aims at the abatement of airfoil self noise, with a new flow porous material constituted by “open foams with directional cavities”. This revolutionary concept allows shaping the macro characteristics (edge geometry, angles) of conventional passive noise reduction techniques, into the micro ones of the porous structure (porosity, cavity orientation), towards the creation of a material able to mitigate noise by both dampening flow fluctuations and reducing acoustic scattering. Addressing both hydrodynamic and acoustic aspects of noise is extremely challenging due to the different flow scales and physical mechanisms involved. The proposed research aims at studying, designing and prototyping inserts for wind tunnel wings with open foams able to work at a multi scale level. Flow features will be studied to shape within the material the optimal flow path for noise mitigation. The study will focus on the following relevant noise sources in aeroacoustics:
1. abatement of turbulent boundary layer trailing edge noise in wind turbine blades;
2. abatement of flap side and leading edge noise in aircraft wings.
The research of the STW project has attracted interest from both institutions and companies leading in aeroacoustic and structural vibration studies (KU Leuven, LM Wind Power, VKI, DNW), which committed to this mission with their participation and in kind contribution. Main activities will be conducted in the laboratories of the TU Delft Faculty of Aerospace Engineering.


Project number


Main applicant

Dr. ir. D.R. Ragni

Affiliated with

Technische Universiteit Delft, Faculteit Luchtvaart- en Ruimtevaarttechniek, Aerodynamics, Wind Energy, Flight Performance and Propulsion (AWEP)

Team members

Dr. R. Hedayati, S. Luesutthiviboon, L.F.L. Rego


15/01/2018 to 01/04/2021