On gas-dynamic similarity of high-pressure hydrogen release into air

The paper discusses the issues of gas-dynamic similarity in the problem of high-pressure hydrogen release into air and the possibility of laboratory modeling of the process by reducing the initial pressure at a fixed ratio of hydrogen and air pressures. The fundamental factor in the considered problem is the probability of hydrogen spontaneous ignition, which significantly limits the applicability of gas-dynamic similarity in modeling the considered process. It is shown, however, that for large values of the hydrogen and air pressure ratio (from 200 to 700 and higher) in view of the small values of the hydrogen ignition delay time, one can speak about the gas-dynamic similarity in a wide range of initial pressures. This should allow laboratory modeling the process of high-pressure hydrogen release with subsequent spontaneous ignition in atmospheric air at reduced pressure.