In this paper, various geometric modifications to landing gear side braces are assessed in terms of their impacts on noise generation. Far-field noise levels are quantified conducting microphone measurements in the University of Toronto's open-jet anechoic wind tunnel. The baseline brace geometry considered was a high-fidelity replica of the side brace designs used in current, twin-aisle, commercial aircraft, and had an I-beam shape. Different combinations of leading- and trailing-edge elements as well as I-beam cavity plugs were added to this baseline shape to evaluate modifications that can reduce noise. The results showed that adding only a leading-edge element on the I-beam resulted in a broadband noise increase in the mid-frequency range, whereas plugging the I-beam cavities in presence of these leading-edge elements brought the noise output of the model back to the levels of the baseline I-beam shape. Installing only a trailing-edge element to the I-beam or filling the cavity while having a trailing-edge element did not induce any significant variations in the noise output compared to the baseline design. Although installing a semi-circular leading-edge and a triangular trailing-edge element along with cavity plugs was a configuration closest to an airfoil shape, it generated a low-frequency broadband noise increase. Opening cut-outs on the I-beam shape of a brace brings weight saving benefits and consequently can be deemed advantageous by aircraft designers. Therefore, noise impacts of rectangular cut-outs on the I-beam frontal area have also been examined. The particular cut-outs studied in this investigation did not show a strong effect on the noise levels of the I-beam. Lastly, a cylindrical brace with an oval cross-section was tested and shown to produce higher noise levels across all frequencies than the baseline I-beam structure. These unexpected noise trends emphasize the need for a better understanding of the flow physics for further elucidation.
