Mitigation of turbulent noise sources by riblets

A feasibility study is presented on the application of riblets to suppress turbulent pressure sources leading a reduction in generation aerofoil self-noise. It shown that can reduce skin friction as well turbulence intensity inside boundary layer. In addition, near-wall structures were found be dissipated quite rapidly when crossing surface. (1) slightly wall fluctuating power spectral density level at low and high frequency ranges, but cause an increase mid range, (2) lateral coherence length scale across large range. As result, have potential trailing edge noise regions. The fundamental mechanism by which layer investigated studying spatio-temporal evolution spots, are commonly regarded building blocks this paper two mechanisms proposed. First, enhanced momentum achieved becalmed region each spot will lead overall obtained spots merge downstream. Second, internal rear part reduced directly re-laminarisation effect.