Nonclassical wave propagation measurements in the high temperature vapor of \(\hbox {D}_{6}\) with the asymmetric shock tube for experiments in rarefaction waves (ASTER)

A novel test setup called the asymmetric shock tube for experiments on nonideal rarefaction waves (ASTER) has been commissioned at Delft University of Technology. The ASTER, which works according to the principle of Ludwieg tubes, is designed to generate and measure the speed of small and finite amplitude waves propagating in the dense vapors of fluids formed by complex organic molecules, therefore in the nonideal compressible fluid dynamics regime. The ultimate goal of the associated research is to prove the existence of nonclassical gasdynamics. The setup consists of a high-pressure charge tube and a vacuum tank separated by a glass disk equipped with a breaking mechanism for rarefaction waves experiments. When the glass disk is broken, an expansion wave propagates into the tube in the direction opposite to the fluid flow. The propagation speed of this wave is measured using a time-of-flight method with the help of four fast-response pressure sensors placed equidistantly in the middle of the tube. The charge tube can withstand pressures and temperatures of up to 15 bar and 400 \(^{\circ }\mathrm{C}\) $_{}^{\circ }\mathrm{C}$ . Preliminary rarefaction experiments were successfully conducted using dodecamethylcyclohexasiloxane, \(\hbox {D}_{6}\) ${\text{D}}_6$ , as the working fluid and at pressures and temperatures of up to 9.4 bar and 372 \(^{\circ }\mathrm{C}\) $_{}^{\circ }\mathrm{C}$  , respectively. The results of an experiment featuring the initial state for which a theoretical model predicts the nonclassical acceleration of rarefaction waves show that the propagation is qualitatively different from that put into evidence by experiments for which the propagation is classic. Upcoming setup improvements and experimental campaigns are planned with the objective of experimentally verifying the existence of nonclassical gasdynamics.