The Research On Hot Jet Initiation Of Rotating Detonation

Successful and effective detonation initiation is one of the key problems of successful application of detonation combustion chamber. The hot jet initiation for rotating detonation combustion has a unique advantage, it is a very efficient way of detonation initiation. But it is necessary to solve some issues with hot jet initiation rotation detonation combustion chamber:geometry size of the initiator, both connection methods, final energy parameters of the hot jet initiation formed, etc. In this paper, for above problems, the process (DDT process) of energy amplified in the hot jet detonator, the mechanism and the structural effect of jet detonator are investigated deeply through theoretical analysis and numerical calculation.In this paper, hot jet detonator was treated as the research object, and the premixed gas of hydrogen and air was taken as the working medium, it was made to simulate numerically the process of the DDT (deflagration to detonation) in the hot jet detonator. With the numerical simulation software FLUENT and single-step chemical reaction model of hydrogen and air in this paper, the N-S equations was resolved, simulates a two-dimension simplified model of detonator was simulated numerically, and the process of forming the detonation hot jet of the detonator for initiation finally was analyzed in detail from a low-energy ignition sources and through complex combustion reaction and the complex interactions of flame surface and shock face. The operational mechanism of the whole process of DDT was analyzed, it was found the DDT operational process is that the premixed gas was ignited firstly to combust slowly by low-energy ignition, through heat generated by combustion was increased and pressure wave was super positioned, deflagration occurs step by step, "hot spots" was formed in this course, localized explosion happens, and ultimately the detonation wave was promoted to form. The process of making initiation ignition about delivering detonation hot jet directly into the rotating detonation combustion chamber was verified numerically, it was found that the effect of detonation is very ideal.By the effect factors of analyzing DDT process, the geometry structure of the detonator was optimized, and it was found that there are several effective ways to accelerate the DDT process, which is, according to the nature of premixed gas, the diameter of the detonator was chosen, obstacles were added to increase spoiler features, the suitable spoiler pitch and the blockage ratio, the appropriate structure, position and spoiler length of spoiler and the appropriate ignition position was chosen, the initial ignition energy was improved, more sensitive gas equivalent ratio and the suitable initial parameters of premixed gas were made to choose. The DDT process were compared and analyzed from physical and chemical factors to obtain higher energy of detonation hot jet for initiation rotating detonation.It was found that, in the terms of the hydrogen and air detonator,there is a more suitable detonator diameter which can make the DDT distance shortest in light pipe; good barrier structure can generate spoiler role to promote the generation of DDT process and reduce greatly the DDT distance; there is optimal value of the ignition position which can take full advantage of using reflection to reinforce initiation process, the higher the ignition energy, the more quicker the DDT process occurs; the distance of the DDT will be affected by both the initial temperature and pressure of the premixed gas and equivalent ratio. It provides a basis for the structural design of the detonator from the analysis and comparison of these factors.