Hydrogen ignition in the process of its pulsed release into the air-containing mixtures under various conditions

Abstract

The article numerically studies the process of pulsed hydrogen release under high pressure into air-containing mixtures under various conditions using the example of release into air and a stoichiometric hydrogen-air mixture. Two cases are considered: hydrogen release into a medium under ambient conditions and into a medium pre-compressed by 11.4 times, which corresponds to the characteristic compression in a gas piston engine. In the simulations, both the initial hydrogen pressure and the radius of the hole through which hydrogen is released are varied. As a result, critical pressure values required for successful ignition of various compositions during hydrogen release through holes of different radii are determined. It is shown that the hydrogen release into a stoichiometric hydrogen-air mixture could lead to the combustion wave propagation in a detonation mode following the ignition. On the one hand, this is important for assessing the risks of hydrogen explosion hazards, and, on the other hand, can become the basis for new technological solutions for stable ignition in combustors without the use of additional devices, such as a spark ignition system. Thus, the work demonstrates that a relatively small mass of hydrogen is required to ignite a stoichiometric hydrogen-air mixture. In this regard, it can be concluded that ignition as a result of a jet flow of hydrogen into a combustible mixture can principally serve as a replacement for spark ignition.