Abstract
This paper presents an experimental study on the aeroacoustics of a flat plate rig with a highly instrumented serrated trailing-edge. The role of near-field flow properties, namely, surface pressure fluctuations and spanwise coherence, in the noise suppression capability of serration is not properly understood. The results from this test rig aim to provide additional insight into the effects of the serration on the hydrodynamic field (flow field) and the scattering of the pressure waves along the trailing-edge. Despite its unconventional size, beamforming results showed a significant reduction of far-field noise over a broadband frequency range. The associated flow field is characterized by mean and spectral analyses of static and dynamic surface pressure measurements as well as hot-wire measurements. The mean pressure coefficient results and the boundary layer velocity profiles over the serrated trailing-edge showed minute differences compared to the baseline straight trailing-edge. However, the frequency-dependent energy content of the unsteady surface pressure fluctuations demonstrates an elevated energy region around the serration edges at low frequencies. Although there is an increase in the energy content of the low frequency pressure fluctuations on the serrated trailing-edge, a significant phase difference of the pressure waves is observed, which may be indicative of destructive interference. The temporal studies regarding the unsteady surface pressure fluctuations corroborate the presence of quasi-periodic large scale structures emanating from the serration edges.
Highlights
The broadband noise radiated from airfoils has become an important research topic due to its ubiquitous presence in daily life in the last few decades
The far-field noise is presented to confirm the validity of using a non-conventional serration of h=d 1⁄4 3:1 and h=k 1⁄4 0:4, by providing evidence that it achieves far-field noise attenuation when compared to a straight trailing-edge flat plate
The results indicate that the primary noise source is located around the trailing-edge, and the serrated trailing-edge attenuates the noise over a broad range of frequencies
Summary
The broadband noise radiated from airfoils has become an important research topic due to its ubiquitous presence in daily life in the last few decades. This paper presents the results of an experimental study of a serrated flat plate under one-sided flow to contribute to the understanding of the noise reduction mechanism of serrated trailing-edges and to provide evidence for noise reduction of large scale serrations (2h % 92 mm, k % 116 mm in width, d=2h 1⁄4 0:16, and k=2h 1⁄4 1:25) in conjunction with the associated flow field. This design may overcome the addressed issues on robustness for current designs, as it is not fragile and can be installed .
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
