Fig. 4: Schematic diagram of the experimental setup.
From: Tunable acoustic vortex generation by a compact rotating disk
Sound pressure at a cross-section 40 mm from the front of the disk (z = 40 mm) was measured using two microphones. The center of the area detected by the microphone is coaxial with the center of the disk, differing only in the z-direction distance. Microphone 1 was kept stationary, fixed on a circle with a radius of 50 mm, and served as the phase reference. Microphone 2 was moved to 36 uniformly arranged points on circles with radii of 10, 20, 30, and 40 mm, along with one point at the center, for a total of 145 measurement points. The acoustic vortex phase distribution was determined by calculating the relative phases between microphone 1 and microphone 2 at each measurement point.
