Blockage of Pitot tubes leads to presentation of inaccurate data to pilots and automatic systems, and has been involved, either directly or indirectly, in several fatal accidents befalling commercial aircraft. This work presents experimental and computational acoustic results for Pitot tubes with the intention of providing a firmer theoretical basis for an acoustic blockage detection system. Three Pitots from two different commercial aircraft were acquired and CT scans used to determine the internal Pitot-static tube geometry. Using this information a three-dimensional finite element acoustic study was performed to determine the variation between blocked and unblocked reflected acoustic waves when subjected to a sinusoidal input. To validate this, supporting experiments were conducted on the same tubes when subjected to a range of blockage types, including tape, pre-deceased insects, foam, and metal. Experimental and numerical results confirm acoustic detection of all tested blockages is feasible in a quiet environment, without any modification to the internal or external design of the Pitot. The frequency range for detection is specific to each of the two Pitot designs, but a common feature is that the blocked/unblocked variation diminishes as frequency increases.
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