The shock tube facility is used as a step generator for the calibration of high frequency response pressure systems. It is the property of SNECMA (Groupe Safran), has been recently installed at VKI and can be used for third party investigations as well.
The facility has a total length of 8 m and is composed of 6 tubes of 100 mm internal diameter, separated by 3 measurement stations and 2 membrane holders. In addition to the end-plate instrumentation which provides a calibration under total pressure excitation, the 3 measurement stations allow the calibration of pressure systems under static pressure excitation as well. The measurement stations allow testing sensors, probes, infinite line pressure systems, etc. Flush mounted fast response piezo-resistive sensors are used as reference sensors.
The construction of the tube allows pressure steps of 2 bar. The exceptionally long length of the tube allows plateau times for the pressure step of about 16 ms, which correspond to a lower frequency limit of about 60 Hz. The high frequency limit is depending on the rise time of the generated step (which is of the order of 1 ms), of the sensor diameter and shock Mach number (for static measurements) but is well above 100 kHz.
The direct product of the shock tube calibration is a time record of the pressure system response to the step input. A digital storage oscilloscope or a high speed data acquisition system are used to record the trace for comparison with the reference sensor and calculation of the frequency response diagram in gain and phase.