Linking dynamic to static pressure by laser interferometry

Abstract

The primary calibration of pressure transducers is at present realized by static methods. This paper describes a new route to gaining traceability for dynamic calibration using the acousto-optic effect. The pressure range under consideration is up to 100 MPa. We set out a description of the general principle employed to gain traceability, the experimental set-ups that are used for the realization and the thermophysical background of the measurements, and some numerical estimates on the expected results for two different pressure-transmitting media are shown.

Dynamic calibration of piezoelectric transducers for ballistic high-pressure measurement

“…First of all, as can be seen in Figure 6, there is peak around 16.7 kHz which matches the frequency of the oscillations as it was determined by equation (13). Secondly, it can also be noticed that the useful signal is mostly below the frequency of 2 kHz.…”

“…The period of the oscillations is constant and is around 60 μs. This period corresponds to the duration (T c ) required for the wave to travel twice the drop weight length (L dw = 0.15 m) which is given equation (13). The speed of the wave c (m/s) is 5020 m/s.…”

“…The last researches in the field of dynamic highpressure calibration were conducted in the works of Bartoli et al [12], Bruns et al [13] and Zhung et al [14]. The goal of the studies was to establish traceable dynamic measurement of the mechanical pressure.…”

Comparing the adiabatic and isothermal pressure dependence of the index of refraction in a drop-weight apparatus

“…This can be traced back to the different thermodynamic processes at work in the static case (isothermal) and in the dynamic case (mostly adiabatic). It had been expected that some difference would exist [21]. Here we show the magnitude of the effect and what it means for the prospect of using the apparatus for dynamic calibration of pressure transducers.…”

“…The distinguishing characteristics of the drop-weight setup discussed here is that the pressure measurement is performed with a laser heterodyne interferometer, via the pressure-dependent index of refraction of the hydraulic fluid compressed by the impacting weight [21,22]. In principle, this makes dynamic pressure directly traceable to static pressure.…”