Unsteady Flow Field in a Shock Tube: Solutions, CFD and Experiments
Bruno Coelho Lima1; Jayme Rodrigues Teixeira Silva1; João Felipe de Araujo Martos1; Paulo Gilberto de Paula Toro2; Marco Antonio Sala Minucci2; Antônio Carlos Oliveira2; Álvaro Francisco Santos Pivetta1; Ana Maria Pereira Lara1; Israel da Silveira Rego2
1 ITA; 2 IEAV
doi:10.20906/CPS/CON-2016-0819
Resumo
The shock tube is a ground-facility widely used in aerospace and aeronautics science and technology for studies on gas dynamic and chemical-physical processes in gases at high-temperature, explosions anddynamic calibration of pressure sensors. A shock tube consists ofa long cylindrical tube with same cross-section, which is separated by a thin membrane, called diaphragm, into two parts. One of them, the low-pressure tube or driven, is filled with the test gas, while the compressed gas is fed into the second part or driver. Ideally, when the diaphragm is suddenly bursted, the compressed driver gas flows into the driven tube, forming instantly a moving shock wave that propagatesthrough the test gas. The distribution of the various physical properties through the shock front is represented as "jumps". After the shock front reaches the shock tube end, it is reflected towards the driver tube, increasing sharply the physical variables over the values behind the incident shock. The aim of this paper is to investigate the transient flowfield and phenomena in a shock tube by means of gas-dynamic theory, computational fluid dynamics (CFD) simulations and shock tube experiments. First, solutions for ideal shock tube operation are calculated, followed by inviscid and viscous CFD simulations. Finally, gas-dynamic experiments in T1 shock tube of IEAv are carried out. Preliminary CFD verification and validation of unsteady shock tube airflow are the following: Inviscid and viscous CFD simulations are in good accordance with ideal shock tube solutions for weak shocks, indicating that the computer programming errors are low (less than 5 %); and both CFD simulations overestimate the experimental results, showing that the sudden diaphragm rupture still need to be considered. Experience and lessons learned herein can be considered with confidence for decision making in shock tube design.
Palavras-chave: Ideal Shock Tube Operation; Transient Flow ; CFD; Shock Tube Experiment; Gas Dynamics