In conventional shock tubes with a diaphragm, many effects related to the burst of the diaphragm can influence shock formation, thus preventing an ideal pressure step change, as predicted by the shock tube measurement model being generated. This paper presents a newly developed diaphragmless shock tube with a quick-acting pneumatic valve, which demonstrates several advantages over conventional shock tubes with a diaphragm. The tests of the developed diaphragmless shock tube were performed using nitrogen at the atmospheric initial driven pressure, and at initial driver gauge pressures from 1 MPa to 7 MPa. The results show that the construction of the developed shock tube effectively reduces the generation of secondary shock waves and mechanical vibrations, which are often generated during the operation of shock tubes, thereby increasing the uncertainty of the shock tube calibration method. The uncertainty analysis shows that the developed diphragmless shock tube can act as a primary time-varying pressure calibration standard, generating pressure steps with a magnitude calculable from its measurement model to characterize the dynamic performance of pressure transducers with a relative expanded uncertainty of less than 0.025.

A connecting tube between the measured object and the pressure sensing element is a common component part of pressure measurement systems. Dynamic characteristics of the resulting fluid oscillator may significantly influence the magnitudes of dynamic measurement errors. This paper presents an experimental analysis of dynamic characteristics of connecting tubes of different lengths and diameters. Inlet step pressure changes were generated by a system of two loudspeakers, and pressure responses were measured by a piezoelectric measurement system. Using the measured responses, the characteristic natural frequencies and damping of the system under discussion were determined. The results were further employed to estimate the response settling time, which is required to sufficiently reduce dynamic measurement errors.