Ignition and transition to detonation under chain-branching kinetics

氢气是一种有吸引力的汽车燃料，因为它燃烧时不会释放二氧化碳或其他温室气体，而且它是燃料电池的首选燃料。从水力发电或风能生产氢气是碳中性的。然而，由于氢与碳氢化合物燃料相比具有明显不同的特性，因此在允许广泛的氢储存和分配设施与人口稠密地区密切接触之前，需要解决重大的安全问题。 同样，在隧道和公共车库中的车辆中储存氢也存在安全问题。 由于氢气非常轻且具有浮力，因此可以通过确保周围有足够的距离来确保户外安装的安全性，而这些距离是不允许公众使用的。然而，在封闭的环境中，严重的问题仍然存在，主要与爆炸的风险有关，氢比其他燃料更容易发生爆炸。爆炸是燃烧的最猛烈的形式，其中燃烧依靠它也支持的冲击波。 因此，爆震波只要遇到可燃混合物就以高超音速传播，并且它们通常需要数十个大气压的压力增加，这是相当具有破坏性的，并且可能导致比最近的Mont-Blanc隧道事故更严重的事故。不幸的是，导致爆炸的机制仍然存在很大的不确定性，即使是氢，其化学性质比其他更复杂的燃料更好地了解，至少在相对较低的压力下。此外，有可靠的实验证据表明，高压氢突然释放到大气中可能会自燃，其机理也不清楚。目前的工作的目标是澄清氢化学的具体功能和爆震和自发射流点火的外观之间的关系。为此，将对一系列设想方案进行数值模拟和数学分析，从相对简单的设想方案开始，到日益复杂和现实的设想方案。

Hydrogen is an attractive automotive fuel because it burns without releasing CO2 or other greenhouse gases, and because it is the fuel of choice for fuel cells. Hydrogen production from hydro power or wind energy is carbon-neutral. However, because hydrogen has a markedly different behaviour when compared with hydrocarbon fuels, there are significant safety issues that need to be resolved before widespread hydrogen storage and distribution facilities are allowed in close contact with populated areas. Likewise, there are safety issues associated with hydrogen storage in vehicles in tunnels and public garages. Because hydrogen is very light and buoyant, outdoors installations can be made safe by ensuring that there is enough distance around where the public is not allowed. However, in enclosed environments, serious issues remain, mostly associated with the risk of detonation, which hydrogen is much more prone to than other fuels. Detonation is the most violent form of combustion, in which combustion rides on a shock wave which it also supports. Thus detonation waves travel at high supersonic speeds as long as they encounter combustible mixture, and they entail a pressure increase usually in the tens of atmospheres, which is quite destructive and could result in accidents more serious than for instant the recent Mont-Blanc tunnel accident. Unfortunately, major uncertainties remain on the mechanisms leading to detonation, even for hydrogen, the chemistry of which is better known than other more complex fuels, at least at relatively low pressures. In addition, there is reliable experimental evidence showing that a sudden release of high pressure hydrogen into the atmosphere may ignite spontaneously, under a mechanism that is not well understood either. The goal of the current work is to clarify the relationship between specific features of hydrogen chemistry and both appearance of a detonation and spontaneous jet ignition. To that effect, numerical simulation and mathematical analysis will be performed for a hierarchy of scenarios, starting from relatively simple ones to increasingly more complex and realistic ones.