Experimental Slat Noise Assessment Through Phased Array and Hot-Film Anemometry Measurements

Dielectric barrier discharge plasma actuators applied to high-lift devices for aerodynamic noise reduction

“…Between this vortex and the undisturbed flow, a free and unstable shear layer develops originating at the cusp and impacting the surface of the cove ( Figure 6). Choudhari and Khorrami (2006) These instabilities that lead to slat noise are probably generated in the shear layer of the slat (PEREIRA et al, 2018). Khorrami (2003) demonstrated that this shear layer is an amplifier of low and medium frequency disturbances.…”

“…Choudhari and Khorrami (2007) also suggests that an optimal strategy to mitigate broadband slat noise should target the shear layer reattachment region, in order to reduce the amplitude of surface pressure fluctuations. Pereira et al (2018) determined the location of the shear layer reattachment point in the slat cove through the coherence between two consecutive hot film sensors, finding that the reattachment position moves slowly toward the slat trailing edge with increasing angle of attack. The model in which Pereira et al (2018) performed their measurements is the same one that will be used in the experiments of the research presented here.…”

“…Pereira et al (2018) determined the location of the shear layer reattachment point in the slat cove through the coherence between two consecutive hot film sensors, finding that the reattachment position moves slowly toward the slat trailing edge with increasing angle of attack. The model in which Pereira et al (2018) performed their measurements is the same one that will be used in the experiments of the research presented here. Thus, the results presented by Pereira et al (2018) were directly used in the research presented at this dissertation, indicating the position in which the DBD-PAs was to be installed, following the suggestion of Chen (2012).…”

“…The model in which Pereira et al (2018) performed their measurements is the same one that will be used in the experiments of the research presented here. Thus, the results presented by Pereira et al (2018) were directly used in the research presented at this dissertation, indicating the position in which the DBD-PAs was to be installed, following the suggestion of Chen (2012).…”

“…46BD microphone sets (which combine a 1/4 in pressure microphone 40BD and a 1/4 in preamplifier 26CB), flush mounted without grid at the test section side-wall, distributed in a modified spiral geometry ( Figure 50) optimized for achieving a high frequency range with minimum beamwidth and side-lobe contamination (FONSECA et al, 2010). Source: Pereira (2018) These microphones have a frequency range of 4 kHz to 70 kHz (±2 dB), a dynamic range of 166 dB, and a calibrated sensitivity of 1.5 to 2.6 mV /P a (obtained with a NC-74 calibrator, which produces a 1.0 kHz, 1.0 P a reference pressure fluctuation). This set of configurations and geometry warrants an array beamwidth smaller than 100 mm for frequencies above 400 Hz (PAGANI JÚNIOR, 2014).…”