Optimisation of Leading-edge Undulations of a NACA 65(12)-10 Aerofoil for Noise Reduction and Aerodynamic Enhancement
* Presenting author
Leading-edge undulations or tubercles of humpback whale flippers have been known as one of biomimetic technologies adaptable to flow control of aerofoils, particularly at post stall conditions. These leading-edge undulations are also known to reduce noise resulting from an interaction with on-coming turbulence. We have recently carried out a parametric studiy of a NACA 65(12)-10 aerofoil with a view to optimise the amplitude and the wavelength of leading-edge undulations for noise reduction and aerodynamic enhancement. A 3x3 test matrix composing of three amplitudes (h = 3%, 6% and 12% chord) and three wavelengths (Lambda = 10%, 20% and 30% chord) was used in the investigation, where lift, drag and noise were measured at the Reynolds number of 100,000. In this test, a turbulence-generating grid was installed at the inlet of the test section to increase the turbulence level in the freestream and to promote transition to turbulence near the leading edge of aerofoils without a need for a trip device. Within the test matrix considered, we found that the best improvement in CL,max is given with the greatest wavelength and amplitude, whereas the maximum noise reduction is obtained with h/C = 0.09 and Lambda/C = 0.2.