Simultaneous calibration of all three acoustic particle velocity components of a pressure-velocity probe

The precise calibration of acoustic particle velocity sensors in pressure-velocity (p-v) probes is still a great challenge and not fully solved, since no standardized reference sensor exists. Current available techniques does not allow for simultaneous calibration of all three components of the particle velocity sensor. Furthermore, most of the available calibration procedures require anechoic conditions and guarantee the calibration just for a restricted frequency range. Therefore, we propose an advanced calibration technique for such p-v probes, which has the following properties: (1) simultaneous calibration of all three components of the particle velocity sensor; (2) does not need any anechoic conditions; (3) is not restricted to a specific frequency range. Thereby, the p-v probe is exposed to a sound field generated by a vibrating piston. The surface velocity of the piston itself is characterized over the whole frequency range by a laser vibrometer. This technique allows us to simultaneously calibrate all three components of the particle velocity sensor, if the azimuth and elevation angles are known. The advanced calibration technique for a three dimensional p-v probe is evaluated by showing first results and comparisons with the nominal correction curves specified by the manufacturer.