Design of a double diaphragm shock tube for fluid disintegration studies.

A double diaphragm shock tube facility for studying liquid-spray atomization and combustion-related phenomena at elevated pressures and temperatures is described. The present shock tube is specifically intended for the investigation of fundamental processes related to fluid disintegration and mixing under realistic engine conditions. Special features of the facility include a variable-area driver section to compensate for shock attenuation, a square test section to allow flow visualization in the postshock region, a skimmer to dispose part of the boundary layer, a heated, fast-response injector, a fully automated gas-filling system, and a new control system and electronics. Test times of the order of 2-5 ms are possible with reflected shock pressures up to 50 bar and temperatures of 2000 K. Details on the setup design, construction and operation are given. Particular emphasis is placed on the accuracy and reproducibility of the test conditions. To that aim, qualification tests have been performed to assess the shock tube performance in terms of effectiveness of the skimmer concept, the capability to compensate for boundary layer effects and the generation of uniform and reproducible test and injection conditions.