共查询到19条相似文献,搜索用时 171 毫秒
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针对高Mach数(Ma ≥ 7)超燃冲压发动机高气动阻力下的燃烧组织问题,提出一种双突扩燃烧室结构方案.使用数值模拟方法考察了射流与双突扩燃烧室组合方式的混合燃烧特性.设计了双突扩超燃冲压发动机模型,在力学研究所JF12长试验时间激波风洞内,开展了Ma=7.0和Ma=9.5的氢燃料点火和燃烧试验对比.在风洞有效试验时间100 ms内,实现了Ma=7.0和Ma=9.5超燃冲压发动机的成功点火与稳定燃烧.在Ma=7.0情况下,进气道采用三维压缩,燃烧室入口设计Mach数Mac=2.5,壁面压力分布实验结果显示燃烧放热靠近燃烧室扩张段上游;在Ma=9.5情况下,进气道采用二维压缩,燃烧室入口设计Mach数Mac=3.5,由于燃烧室流动速度特别高,燃烧放热靠近燃烧室扩张段下游. 相似文献
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引入水蒸气非平衡相变的动力学模型,并在水蒸气真实物性的基础上,建立了水蒸气超声速非平衡流动的守恒型数值计算模型,采用对激波捕捉具有高精度和高分辨率的Roe-FDS格式,数值捕捉了水蒸气超声速流动中的非平衡相变与凝结激波。以非平衡相变中液相质量增长率为基准,将非平衡凝结相变引发的凝结激波划分为凝结激波起始发生区、凝结激波交汇区和凝结激波消退区三个区域,分析了凝结激波的形成机理,得到了凝结激波发生及发展的"X"型分布特征,并归纳了凝结激波的分区物理特性和热力学特性。 相似文献
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为了研究高Mach数超燃冲压发动机和斜爆轰发动机的内流场燃烧流动机理,首先用CJ爆轰理论对超燃冲压发动机的内流场特性进行了理论分析,给出了燃烧室流场的气动规律,理论分析结果与现有实验结果吻合得非常好.其次,根据理论分析结果,提出了高Mach数超燃冲压发动机和斜爆轰发动机的气动设计原则.最后,根据提出的气动设计原则,设计了高Mach数斜爆轰发动机,飞行Mach数为9,对斜激波诱导燃烧机理开展了二维数值模拟研究.数值模拟结果表明,在高Mach数下,斜爆轰发动机燃烧室内可以得到稳定的燃烧流场. 相似文献
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基于D1Q4可压缩格子Boltzmann模型,按照流通矢量分裂方法的思路,采用坐标旋转技术构造求解三维带化学反应Navier-Stokes方程对流通量求解器.结合有限体积法求解三维化学非平衡流Navier-Stokes方程,采用时间算子分裂算法解决化学反应刚性问题,数值模拟超声速化学非平衡流的三个经典算例.数值结果表明:在高马赫数下,采用D1Q4可压缩格子Boltzmann模型构造的三维对流通量求解器数值模拟中没有出现非物理解,同时在超声速化学非平衡流场中正确分辨激波、燃烧波等物理现象,精度和分辨率均较高,验证了本文构造的三维对流通量求解器的可靠性,拓宽了D1Q4可压缩格子Boltzmann模型的应用范围,为计算超声速化学非平衡流提供一种新方法. 相似文献
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可燃悬浮寺燃烧诱导激波可其加速过程研究 总被引:1,自引:0,他引:1
以铝粉为例,基于双流体模型,分别采用TVD格式和MacComack格式计算气相和颗粒相流场,基于Arrihenius定律及管道壁面湍流k-ε模型计算流场反应速度,对水平燃烧管内可燃悬浮粉尘在弱点火条件下激波的产生及加强过程进行了理论分析与数值模拟。研究发现,壁面湍流在火焰加速及燃烧诱导激波过程中起着关键作用,数值计算结果揭示了可燃悬浮粉尘云中压缩波到激波的转捩机制及气固两相流场参数的变化规律。计算 相似文献
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针对激波破坏超声速气膜冷却的机理,本文提出了一种壁面开孔的结构,数值研究结果表明:一方面,壁面开孔的结构能使激波作用的区域壁面附近的压力分布较均匀,从而使近壁区的马赫数分布比不开孔的壁面要高,有利于超声速气膜冷却。同时在激波的作用下,冷却气体可以通过开孔壁面的孔进入槽道内,而在槽内的下游再从孔里流出,保护下游的壁面,这... 相似文献
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采用数值模拟的方法,研究了沸腾雾化喷射过程中热壁面薄液膜层受到液滴碰撞扰动时液膜层内汽泡运动,相界面变化和由此引起的壁面换热特性.模拟结果显示汽泡生长初期相界面变化与液膜层内二次核化特征与文献结果吻合良好,汽泡生长后期相界面变化存在滞后.讨论了液滴下降速度.液滴直径与初始位置,多液滴碰撞对液膜层内流动与壁面换热的影响. 相似文献
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《Proceedings of the Combustion Institute》2023,39(3):2895-2903
The unsteady, reactive Navier-Stokes equations with a detailed chemical mechanism of 11 species and 27 steps were employed to simulate the mixing, flame acceleration and deflagration-to-detonation transition (DDT) triggered by transverse jet obstacles. Results show that multiple transverse jet obstacles ejecting into the chamber can be used to activate DDT. But the occurrence of DDT is tremendously difficult in a non-uniform supersonic mixture so that it required several groups of transverse jets with increasing stagnation pressure. The jets introduce flow turbulence and produce oblique and bow shock waves even in an inhomogeneous supersonic mixture. The DDT is enhanced by multiple explosion points that are generated by the intense shock wave focusing of the leading flame front. It is found that the partial detonation front decouples into shock and flame, which is mainly caused by the fuel deficiency, nevertheless the decoupled shock wave is strong enough to reignite the mixture to detonation conditions. The resulting transverse wave leads to further mixing and burning of the downstream non-equilibrium chemical reaction, resulting in a high combustion temperature and intense flow instabilities. Additionally, the longitudinal and transverse gradients of the non-uniform supersonic mixture induce highly dynamic behaviors with sudden propagation speed increase and detonation front instabilities. 相似文献
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L. F. Figueira da Silva Joo L. F. Azevedo Heidi Korzenowski 《Journal of computational physics》2000,160(2):858
Unstructured adaptive grid flow simulation is applied to the calculation of high-speed compressible flows of inert and reactive gas mixtures. In the present case, the flowfield is simulated using the 2-D Euler equations, which are discretized in a cell-centered finite volume procedure on unstructured triangular meshes. Interface fluxes are calculated by a Liou flux vector splitting scheme which has been adapted to an unstructured grid context by the authors. Physicochemical properties are functions of the local mixture composition, temperature, and pressure, which are computed using the CHEMKIN-II subroutines. Computational results are presented for the case of premixed hydrogen–air supersonic flow over a 2-D wedge. In such a configuration, combustion may be triggered behind the oblique shock wave and transition to an oblique detonation wave is eventually obtained. It is shown that the solution adaptive procedure implemented is able to correctly define the important wave fronts. A parametric analysis of the influence of the adaptation parameters on the computed solution is performed. 相似文献
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凝聚炸药爆轰在边界高声速材料约束下传播时,爆轰波会在约束材料界面上产生复杂的折射现象.本文针对凝聚炸药爆轰波在高声速材料界面上的折射现象展开理论和数值模拟分析.首先通过建立在爆轰ZND模型上的改进爆轰波极曲线理论给出爆轰波折射类型,然后发展一种求解爆轰反应流动方程的基于特征理论的二阶单元中心型Lagrange计算方法来数值模拟典型的爆轰波折射过程.从改进爆轰波极曲线理论和二阶Lagrange方法数值模拟给出的结果看出,凝聚炸药爆轰波在高声速材料界面上的折射类型有四种:反射冲击波的正规折射、带束缚前驱波的非正规折射、带双Mach反射的非正规折射、带λ波结构的非正规折射. 相似文献
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K. A. Avdeev V. S. Aksenov A. A. Borisov D. G. Sevastopoleva R. R. Tukhvatullina S. M. Frolov F. S. Frolov I. O. Shamshin B. Basara W. Edelbauer K. Pachler 《Russian Journal of Physical Chemistry B, Focus on Physics》2017,11(2):261-271
The entry of a shock wave from air into water containing reactive gas (stoichiometric acetylene–oxygen mixture) bubbles uniformly distributed over the volume of the liquid has been numerically investigated using equations describing two-phase compressible viscous reactive flow. It has been demonstrated that a steady-state supersonic self-sustaining reaction front with rapid and complete fuel burnout in the leading shock wave can propagate in this bubbly medium. This reaction front can be treated as a detonation-like front or “bubble detonation.” The calculated and measured velocities of the bubble detonation wave have been compared at initial gas volume fraction of 2 to 6%. The observed and calculated data are in satisfactory qualitative and quantitative agreement. The structure of the bubble detonation wave has been numerically studied. In this wave, the gas volume fraction behind the leading front is approximately 3–4 times higher than in the pressure wave that propagates in water with air bubbles when the other initial conditions are the same. The bubble detonation wave can form after the penetration of the shock wave to a small depth (~300 mm) into the column of the bubbly medium. The model suggested here can be used to find optimum conditions for maximizing the efficiency of momentum transfer from the pressure wave to the bubbly medium in promising hydrojet pulse detonation engines. 相似文献
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The characteristics of the supersonic flow of the laser heating technique for producing micro-scale metallic particles were investigated in this study. A numerical model was established to predict the flow fields and particle trajectories leaving a spray nozzle with shock wave effects. The compressible flow of the shock waves and the trajectories of particles in diameters of 1–20 μm were simulated and compared with the flow visualization. In the experiment, a pulsed Nd-YAG laser was used as heat source on a carbon steel target within the nozzle, and the carbon steel particles were ejected by high-pressure air. The result shows that the shock wave structures were generated at various entrance pressures, and there is a significant increase in the amount of carbon steel particles and the spraying angles by increasing the entrance air pressure. 相似文献
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预混火焰界面的RM(Richtmyer-Meshkov)不稳定现象在自然界和工程实践中十分常见,但目前关于反应性RM不稳定的研究主要集中于均匀介质的情况,而实际中的预混气体往往是非均匀的,因此开展非均匀介质中火焰界面演化和混合特性的研究十分必要。采用带单步化学反应的Navier-Stokes方程和高精度数值格式,研究了预混火焰界面在入射激波及反射激波作用下的RM不稳定过程,考察了化学反应活性以及介质非均匀性对RM不稳定过程中火焰界面混合特性的变化规律的影响。结果表明,在入射激波作用后的阶段,在均匀介质中的火焰界面形态呈现典型的"钉-帽-泡"结构,化学反应活性越强,界面的"泡"结构和"钉-帽"结构增长越快;而在非均匀介质中,火焰界面形态则呈现"钉-钉"结构,界面在流向速度差的诱导下被更大程度地拉伸。在第一次反射激波作用后的阶段,混合区的增长速率不依赖于反应活性和均匀性,仅与流动特性有关。时间尺度的研究表明,大尺度流动是反应性RM不稳定的主导因素,其次是化学反应,最后是小尺度混合,化学反应的强化会抑制大尺度流动,非均匀性会强化大尺度流动。 相似文献