Features of the hydrodynamic calculations for technical expertise of accidental explosion
This paper presents some features of calculations to analyze the accident and to determine the values for calculations of primary source data on the basis of technical expertise of accidental explosion on ethane supply pipeline. The accident development scenario is shown and the measures of responsibility for involved parties are established. Before numerical calculation of the probable scenario of the accidental explosion it have been estimated the emergency consumption of gases. Two methods of estimation of emergency consumption are presented. The first one is based on the gas- dynamic ratios describing its leakage from pipeline, and the second one is describing interrelation of the area of free-flow flame front with gas consumption value. The relevant calculation results are presented. Numerical calculations of explosive cloud formation in relation to particular accident are also presented. Calculation of concentration fields which could appear in case of gas leakage is shown. The conclusion is that modelled accidental explosion relevant to real one only if the values of gas consumption have been calculated for various combustion zones according to their dimensions. It have been established that the flames generated by leakages from gas pipeline have to be significantly less than it were observed during accident, and areas of possible ignition of clouds formed by different sources do not overlap. It have been determined that ignition of one gas cloud couldn’t lead to spreading of the flame on near-by cloud and the ignition area observed during accident could be significantly larger. It is shown that ignition of the air-gas mixture in such accident is completely excluded when the source of ignition inside or near the car because the concentration of gas near the car can’t exceed 0.6 %. The time dependence of gas concentration near the car is given for several scenarios of the accident. The impact of ignition source on formation of air-gas clouds and on the accident development taking into account the data of comparative analysis of concentration fields formed by various sources is shown.