Identifying the high-frequency response of a piezoelectric pressure measurement system using a shock tube primary method

Abstract

The pressure transducers employed in dynamic pressure applications are calibrated using static pressure standards due to the lack of metrological traceability for time-varying pressure measurements, which limits the achievable accuracy of time-varying pressure measurements. This paper proposes and evaluates a method for identifying the frequency response function of a pressure measurement system in the high-frequency range using an independent, traceable pressure step signal generated in a shock tube as the reference input signal. The identification of the frequency response function for a piezoelectric pressure measurement system with a developed diaphragmless shock tube was performed using nitrogen at the atmospheric initial driven pressure and at the initial driver gauge pressures from 4 MPa to 10 MPa. The uncertainties of the amplitude and phase frequency characteristics of the piezoelectric pressure measurement system under calibration were determined by considering the uncertainty contributions of the pressure step amplitude generated within the shock tube and the arrival time of the initial shock front at the end-wall of the driven section, respectively, the repeatability and the systematic errors. The uncertainty analysis shows that the proposed method used with the developed diaphragmless shock tube determines the amplitude ratio of the piezoelectric pressure measurement system with a relative expanded uncertainty of less than 5% and a phase lag with an expanded uncertainty of less than 9° in the 10 kHz range for all the observed initial driver pressures.