Nowadays, duct acoustics is very important in aerospace engineering, the measurements of sound pressure in a duct experiment are much easier than the associated particle velocity, while to attain the sound power, particle velocities are necessary. In our previous paper, a particle velocity imaging method of acoustic spinning modes propagating within a circular duct simply with surface pressure information is introduced. The proposed method is developed in a theoretical way and the theoretical solutions in a circular straight duct are used to validate the method. In this paper, to test the validity of this method further, CAA results including sound pressure and associated particle velocities on a cross plane outside the duct are attained and used to run the simulation case with the observer method. In the simulation, the acoustic particle velocities on the test section can be reconstructed with a good agreement to CAA solutions. Preliminary experiment of in-duct circular microphone array is also conducted to validate the feasibility of this algorithm in applications. The results prove the validity of this method in the region where the governing equations are LEE, suggest the potential and applications of the proposed method.
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