Computer approximation of air gauge dynamic characteristics using the sine input test rig

The paper describes the test rig dedicated for air gauge dynamical characteristics assessment. The computerised system enables measurement of the amplitudes of back-pressure pk dependent on the input signal circular frequency ω. Dedicated software performs full control on the calibration procedure, which consists of setting a rotational speed and registration of measuring signal, and further data processing. Circular frequency ω was gradually changed with the appropriate step, in order to obtain a series of frequencies in the range from 0.1 to 20 Hz. The response of a measurement system was registered as a sinusoidal curve which after smoothening and interpolation procedures provided an amplitude-frequency graph with its main characteristics, such as time constant and the frequency f0.95 that generated dynamic error 5%. It was demonstrated that sine input dynamic calibration corresponds with real conditions of the in-process measurement with air gauges