On The Numerical And Experimental Study Of The Chemical Reaction Mechanism And The Propagation Mechanism Of Gaseous Detonations

The research of the detonation has extensive practical significance. Detonation is not only a process of fluid dynamics, including complex chemical reaction kinetics, accompanied by a large amount of energy release. The great energy released detonation can cause a lot of devastating disaster in the production and natural life, such as explosion accidents. So in order to protect people’s property, reduce the explosion hazard, we need to study the intrinsic dynamics of detonation and the transmission mechanism. Then the detonation were controlled effectively, suppressed at the beginning, or reduced to a minimum. On the other hand, with the further study of the intrinsic dynamics, the energy can be applied to the field of conventional weapons, the design of propulsion system, detonation engine, etc. In this paper, the chemical reaction mechanism and the transmission mechanism are studied through the numerical simulation and experiments. The important conclusions are given as follows: 1. The 2H₂ + O₂ and 2H₂ + O₂ + Ar with initial pressure varing from 10 to 25 KPa are studied in steel pipe（D = 95 mm）. The variation of cellular structure of detonation waves is investigated. The more argon gas the bigger cellular structures were obtained. The width of the cellular decreases linearly with the increase of the pressure at logarithmic coordinate axes, then the formula λ=C.P^-n is obtained. According to the equation can predict the initial pressure. 2. The advantages and disadvantages of different chemical reaction modes are compared. Then in order to study the details of the detonation wave, the 9 components of 48 reactions of a detailed chemistry model with is adopted which taking into account the role played by the chemical components in the form detonation wave. For reactive Euler equations with stiff source terms, a additive Runge-Kutta method is introduced to solve the stiff problem. A fifth-order WENO scheme is applied to discrete the spatial terms. Based on the MPI platform, a parallel program is developed to run numerical simulations. 3. The Mach reflection of detonation wave on different wedges is investigated. The regular cellular detonation wave is disturbed when the Mach reflection occurs, h making the cells smaller and the shape distorted. It is shown from the numerical results that the trajectory of the triple points got close to be a linear distribution and the triple points decreases with the increase of the angle. The pressure on the wedge surface increases especially at the apex which suffer higher pressure. The state of the chemical reaction was indicated by the intermediate concentration in which the incident shock was weaker than the Mach stem. Different species played different role in the detonation. The concentration of reactants and the final products vary sharply; however, the concentrations are little through the whole reaction. 4. The different bend curvature’s influence on the detonation wave propagation was analyzed though the numerical simulation system. The intrinsic dynamics were revealed. Detonation wave was affected by the rarefaction wave and compression wave in the bent pipe. With bending angle increasing, continuous expansion wave makes the detonation from critical detonation to failure near the inner wall. The numerical simulation results show that when the regular cellular detonation wave propagates through the bend section, diffraction near the inner wall causes detonation cell size increase and detonation reflection occurs on the bottom wall resulting in decrease of cell size.