【作者】 洪滔；

【导师】 秦承森；

【作者基本信息】 中国工程物理研究院 ， 工程力学， 2004， 博士

【摘要】 本文对气体与碳氢化合物液体燃料颗粒以及悬浮铝粉尘中的非定常两相爆轰进行了理论和数值研究。建立了两相系统中爆轰增长与传播的模型，用有限差分方法编制了两相系统非定常爆轰波发展与传播的数值模拟程序，对两相爆轰波进行了详细的数值模拟，得到两相爆轰波参数，两相爆轰波的浓度极限和临界点火能量。 首先对两相爆轰研究进行了回顾和总结，对两相爆轰所研究的范围、以及两相爆轰中所涉及的问题进行了探讨，从而对两相爆轰理论研究要解决的问题及研究中的热点和难点有充分的了解。 对两相爆轰原有的ZND模型进行了讨论，探讨了在两相爆轰模型中如何考虑两相间相互作用、化学反应等一些主要因素及其影响。同时指出了原有的ZND模型的不足，如对化学反应过程的考虑过于简单化。 建立了非定常的气体—燃料液滴两相系统爆轰波的理论模型，并对两相爆轰波的发展与传播进行了数值模拟。气体考虑组分的变化，化学反应用一步、三步反应模型进行描述。数值模拟得到与实验符合的结果。在此基础上针对化学反应参数对两相爆轰波的影响进行了数值模拟。数值模拟结果表明化学反应率对爆轰CJ参数的影响并不明显，但对气体—燃料液滴两相系统的爆轰极限有明显的影响。在相同的起爆能量的条件下，化学反应率越大，两相系统的爆轰极限的下限越小，上限越大。计算了不同燃料当量比时的点火能量。当量比φ=2时所需的点火能量比φ=1时所需的点火能量大得多。这一点，两相爆轰与气体中的爆轰点火能量的实验结果是一致的。 研究了铝颗粒的激波点火问题。对铝颗粒在激波后气流作用下被加速、升温直至点火的整个过程进行了数值分析，得到铝颗粒在激波后气流作用下的点火延时并与实验比较；提出一个新的铝颗粒激波点火判据，该判据基于对铝颗粒的热应力分析。由于铝的热膨胀系数比其氧化物大，受热时只要温度升高70℃，其氧化层就会破裂。该判据认为如果颗粒在温度达到铝的熔点且铝完全熔化时，激波后的气流对颗粒的作用力引起氧化膜的进一步破裂，将导致点火的发生。但如果激波后的气流不能使氧化膜进一步破裂，铝颗粒将在其氧化物的熔点点火。用该判据得到的铝颗粒激波点火延时与实验符合很好。 建立了非定常的悬浮铝粉尘爆轰波两相流体力学模型，并进行数值模拟。模型考虑气体与粒子间的温度和速度的差异，爆轰波中铝颗粒点火采用新判据，考虑了一些实际因素如爆轰波管壁的阻力和对流热传导、粗糙的铝颗粒表面引起表面积增加以及粒子颗粒尺寸分布对放能的影响，尤其是考虑了三氧化二铝在高温下的分解反应，得到的爆轰波速度及铝颗粒点火距离与实验结果符合。通过数值模拟得到不同浓度的悬浮铝粉尘的爆速，得到了爆轰波压力历史曲线的变化，并由此得到悬浮铝粉尘中爆轰极限的下限。悬浮铝粉尘具有很低的爆轰极限下限值。 用一维数值模拟程序对爆轰波的不稳定性问题进行了数值模拟，得到了CZH6、CZHZ，CZ比与空气混合物中爆轰波的振荡和振荡波长，并试图将振荡波长与爆轰波的胞格尺寸联系起来。由不同的步长的解得到的压力振荡解有明显的区别，振荡的振幅没有趋于一致，但激波转爆轰的位置即第一次压力振荡的位置趋于一致，得到的压力振荡平均波长趋于一致，并与实验得到的爆轰波胞格平均长度接近。更多还原

【Abstract】 Unsteady detonation in gas-fuel droplet systems and suspended aluminum dust was theoretically, numerically studied in this thesis. A model of detonation in two-phase systems was set up and numerically simulated with finite difference method. Numerical simulation program was designed and used to calculate the development and propagation of detonation in two-phase systems. The parameters of detonation in two-phase systems were obtained. Detonation limit and critical ignition energy were also obtained by calculation.The investigation for detonation in two-phase systems past years was reviewed and summarized. The problems related on the two-phase detonation were discussed. The problem involved in two-phase detonations was reviewed to know what was the most concerned in the research.ZND model of two-phase detonation was reviewed to understand how to consider the chemical reactions and the effect of two-phase flow between gas and particles in the systems. It was realized the deficiency of inchoate ZND model such as the over-simplified of the chemical reactions.A model was set up to describe unsteady detonation in gas-fuel droplet systems. The change of components in gas was taken into account. Chemical reaction was described with one-step and three-step reaction mechanisms. Numerical simulation results were well agreement with experimental ones. The influence of parameter of chemical reaction rate was further calculated. It was indicated that parameter of chemical reaction rate had little influence on the parameters of detonation in gas-fuel droplet systems whereas the detonation limit was obviously influenced from the results of calculation. In the same condition of ignition energy, the greater of chemical reaction rate, the lower of lower detonation limit and higher of upper detonation limit. Critical ignition energy was also calculated. The critical energy as the equivalence ratio (j)=2 was much more than that as =1. This result was consistent with the experimental one in gas detonation.The shock ignition of aluminum particles was analyzed in this thesis. The acceleration, rising of temperature by heat transfer of the particle was calculated in the flow field behind shock waves. The ignition time delay of particle was obtained and compared with experimental one. It was assumed a new criterion for shock ignition of aluminum particles. It was based on the analysis of thermal stress of aluminum particles. The results showed that as the temperature of aluminum particle increased about 70C, crack was developed in the oxide film shell of the particles. The criterion was that if the crack was enlarged by gas flow behindshock wave and the oxide film lost its protection to aluminum as the temperature of particle reached aluminum melting point and the aluminum was all melted, aluminum particle would be ignited, otherwise aluminum particle would be ignited at its oxide melting point.Model of the detonation in suspended aluminum dust in detonation tube was set up and numerically analyzed. The differences of velocity and temperature between gas and particles were considered. The dissipation by the convective heat transfer and viscosity through tube wall was taken into account. It was considered the influence of increase of surface area of aluminum particle because of its coarseness on the detonation velocity and ignition of particle. New criterion of ignition of aluminum particles in detonation waves was used. The decomposition of aluminum oxide was taken into account. Development and propagation of aluminum dust detonation in detonation tube was numerically simulated. Velocity of detonation and ignition distance of particles was obtained and well agreement with experimental ones. The distribution of pressure, density, velocity and temperature in the flow field of detonation wave was also obtained. The parameters of detonation in two-phase systems with different concentration were calculated and the lower detonation limit in suspended aluminum dust was very low.The nonlinear instability of one-dimensional detonatio更多还原