This paper presents the preliminary results on the aeroacoustic and aerodynamic performances of a NACA65-(12)10 aerofoil subjected to 12 sinusoidal leading edges. The serration patterns of these leading edges are formed by cutting into the main body of the aerofoil, instead of extending the leading edges. Any of the leading edges, when attached to the main body of the aerofoil, will always result in the same overall chord length. The experiment was mainly performed in an aeroacoustic wind tunnel facility, although a separate aerodynamic type wind tunnel was also used for the force measurements. These sinusoidal leading edges were investigated for their effectiveness in suppressing the laminar instability tonal noise (trailing edge self-noise) and turbulence-leading edge interaction noise. The largest reduction in aerofoil noise tends to associate with the sinusoidal leading edge of the largest amplitude, and smallest wavelength. However, noticeable noise increase at high frequency is also observed for this combination of serration. In terms of the aerodynamic performance, increasing the serration wavelength tends to improve the stall angles, but the lift coefficient at the pre-stall regime is generally lower than that produced by the baseline leading edge. For a sinusoidal leading edge with large serration amplitude, the effect of the reduction in "lift-generating" surface is manifested in the significant reduction of the lift coefficients and lift curve slope. The sinusoidal leading edge that produces the best performance in the post-stall regime belongs to the largest wavelength and smallest amplitude, where the lift coefficients are shown to be better than the baseline leading edge. In conclusion, large amplitude and small wavelength is beneficial for noise reduction, whilst to maintain the aerodynamic lift a small amplitude and large wavelength is preferred.
a b s t r a c tTraining to qualify as a manual ultrasonic inspector takes a long time and costs a considerable amount of money. We developed a virtual training environment using an innovative dead-reckoning optical sensor that yields translational position which offers additional information to operators and examiners alike. The training environment contains a library of test scenarios, shows surface coverage, measures the time of inspection, indicates detected defects and provides a performance score. Our test-bed trial results using a pool of Ultrasonic Test (UT) qualified and unqualified participants on two virtual training blocks that contain 2 flaws each reveal 100% detection and an accuracy of 5 mm in locating defects in more than 50% of the measured defect locations.
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