Commissioning And Analysis Of The Test System For The Gas Explosion Shock Tube

Gas explosion has been interpreted from various angles, such as ignition and propagation of gas explosion in complex geometry, under semi premixed condition, laser and spectral measurements study on gas explosion flow field(self luminescence), mechanism research on gas explosion suppression method, etc. However, most of the measurements are carried out in a small scale, and the results can not be directly used in the experiment of large scale gas explosion. Though the measurement of gas explosion has also been carried out in large scale pipeline, the data was unstable and rough, so in this thesis, the experimental study of gas explosion is carried out from the middle scale pipeline, which has the advantages of data stability and scale.Chemical reactions(including ignition) and shock wave propagation is strongly nonlinear phenomena, and the nonlinear will lead to differences in different scale pipeline deflagration phenomenon. The research results in small scale can not be directly extended to large scale pipeline, the explosion phenomenon does not have the simple geometric similarity. This thesis mainly studied gas explosion propagation in middle scale pipeline(200mm×200mm), and gained the preliminary understanding of size effects from angles of pressure and flame propagation speed.The experiment mainly consists of shock tube system, measurement system, charging and distributing system, vacuum system and auxiliary system. In the experimental process, the related equipment has been innovated and improved, including photoelectric sensor system, flame retardant system, anti false trigger system, transient spectroscopy system of gas explosion process, which can solve the pervasive problem of false trigger, flame signal acquisition, time delay synchronization control, transient spectrum and so on in gas explosion experiment.This thesis has carried out a simple test of ignition energy, and pressure versus time curves under conditions of solid wall reflection and film rupture have been experimental studied and in-depth analyzed. This thesis also described the experimental effects by using the self-developed false trigger section in measurement system, and discussed the change of gas deflagration flame changes with time and shock wave pressure changes with time, as well as the change of precursor shock wave pressure and flame at different locations, and carried out a simple test of the mercury lamp and candle transient spectrum. Results showed that the effects of different boundary constraints on the reflector end of explosion shock tube were different, and the reflection effects of weak diaphragm(similar to the bursting diaphragm) and the solid wall(strong constraint) on shock wave and flame were also different. According to the overpressure, the peak value and duration of the shock wave could be reduced by using the diaphragm bursting. The width and speed of the flamelet were not repeatable, which explained that the mesoscale pipeline deflagration presented turbulence instability, also verified that the DDT process is unsteady.