Noise characteristics of an aircraft's main landing gear structure

Aeroacoustic wind tunnel tests and simulation analysis were performed for aerodynamic noise characteris-tics of an aircraft's main landing gear component. The sound field radiated from the structure was measured in an aeroacoustic wind tunnel at different wind speeds. The noise spectra were evaluated with micro-phones. Detached eddy simulation was used to build a flow field around the structure. The sound source strength and location were calculated with the vortex sound theory. The acoustic field was calculated via FW-H equation. The frequency spectra, the directivity characteristics and its mechanism of the noise were subsequently studied. The results indicated that the spectra in lower and middle frequency ranges from the simulation agree with those from the tests; the noise radiated around the structure is a broadband noise; the spectra and dominant frequencies increase with increase in wind speed; in the spectra, there are two energy peaks corresponding to the inter-action noises between shock absorber and strut as well as shock absorber and bogie, respectively; the pressure fluctuation forming the noise sources is on the surface of the lower part of the shock absorber; the shock absorber and bogie are the main contributors while the strut is the least contributor to the total noise; noise radiation has unsymmetric directivities.