Wheels are major noise sources on landing gears. Accurate numerical predictions of wheel noise can provide insights into landing gear noise generation mechanisms and help improve landing gear noise prediction models. Previous simulations have been conducted on an isolated high-fidelity wheel model containing a tyre, a hub, a sidewall and two rim cavities. The hub cavity was an important middle frequency noise source due to the first and second hub cavity depth modes, and the rim cavities were major high frequency noise sources. This work investigates the major noise sources in different frequency ranges of two tandem wheels, with the same geometry as the previous isolated wheel case, by performing high-order numerical simulations at M = 0.23. This paper focuses on the mechanisms and characteristics of the wheel interaction noise. The aerodynamic results are validated against experiments and demonstrate reasonable agreements. The flow interactions are found to be mainly in the side direction with a spectral peak in the side force at a Strouhal number of 0.19, based on the wheel width, which is due to a flapping shear layer mode in the gap. The downstream wheel is the major noise source and has a favourable sound radiation direction to the sideline. The effects of the downstream wheel hub and rim cavities are isolated by covering them in the simulations. The flow interactions dominate the hub cavity depth modes in the generation of middle frequency downstream wheel noise. For high frequency noise, covering both the hub and rim cavities on the downstream wheel only, reduced the noise radiated towards the ground. This high frequency noise reduction was not achieved when the hub cavity alone was covered.
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