共查询到19条相似文献,搜索用时 156 毫秒
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亚声速段横向射流对Coil性能影响的数值研究 总被引:2,自引:0,他引:2
在化学氧碘激光的混合喷管内发生的是一个气体动力学、化学反应动力学以及光学等相互耦合的复杂过程,每个过程都对COIL性能有着至关重要的影响.利用三维CFD技术,通过求解层流Navier-Stokes方程与组分输运方程,对简化后的化学氧碘激光RADICL模型进行数值模拟与分析,对COIL的气动和增益特性进行探讨.在不同的射流穿透条件下,计算COIL混合喷管中的混合与化学反应过程,发现穿透深度决定了增益的分布特性以及过度穿透条件下的非定常结构. 相似文献
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采用CLNST引入的扰流气注入技术对连续波氟化氘/氟化氢化学激光器进行数值模拟研究。模拟其3维流场有化学反应,但不考虑激射的情况。计算结果显示:加入扰流气后,平行注入的主副气流混合增强明显,气流混合速度明显加快,在喷管出口平面5 mm处即扩散至副喷管中心线位置,且小信号增益系数值明显增强。分析了流场结构得出:扰流气增强气流混合的主要方式在于使反应界面拉伸和扭曲,同时观察到有弱漩涡产生,但沿气流方向较快耗散掉,对流场影响较小。 相似文献
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直排型DF/HF化学激光器双喷管模型启动特性 总被引:2,自引:1,他引:1
建立了一套直排型DF/HF化学激光器气流通道双喷管小型实验装置,通过选择不同副气流总压(模拟燃烧室气流)进行实验,研究了副气流总压对双喷管实验装置启动特性的影响。实验结果表明:随着副气流总压的增大,装置的启动压力降低,盲腔条件下的启动压力明显高于有副气流时的启动压力。因此,先通入燃烧室气流,再开通引射气流,对直排型连续波DF/HF化学激光器的启动是有利的。采用1维处理方法,建立了从引射气流喷管入口、副气流喷管入口到扩压器出口的理论模型,得到了与实验一致的规律。由于1维理论中采用了一些近似处理,实际启动压力比理论数据高20%~31%。 相似文献
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应用改进的3维化学反应流程序,对基于RADICL装置、以氮气为稀释气体的化学氧碘激光喷管流动做了数值模拟。给出了达到合适副气流穿深的主副气流匹配条件,考虑了提高水汽流量、改变主副气流总温对增益系数的影响,比较了与以氦气为稀释气体的不同特点。结果发现:氮气作为稀释气体条件下,混合气体的流速低,静压大,在亚声速区驻留时间长,碘分子离解快,使得增益系数峰值增大,且下降快。模拟结果提示:改变喷管结构,将副气流喷孔下移,增益分布得到了改善。 相似文献
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COIL基于小信号增益系数的最佳流量配比选择 总被引:1,自引:1,他引:0
氧碘化学激光器(COIL)的混合喷管内发生的是气体动力学、化学反应动力学以及光学等相互耦合的复杂过程,每个过程都对COIL性能有着至关重要的影响。利用3维CFD技术,通过求解层流Navier-Stokes方程与组分输运方程,结合10种组分和21个基元反应的化学反应模型,对简化后的化学氧碘激光RADICL模型在亚声速段横向射流情况下,不同的主副流流量配比对小信号增益系数的影响情况进行了比较与分析。结果证明:过高或过低的碘分子浓度均不利于产生合理的小信号增益系数;存在最佳流量配比使小信号增益系数得到显著提高且分布均匀。 相似文献
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Chemical oxygen iodine laser (COIL) is a high-power laser with potential applications in both military as well as in the industry. COIL is the only chemical laser based on electronic transition with a wavelength of 1.315 μm, which falls in the near-infrared (IR) range. Thus, COIL beam can also be transported via optical fibers for remote applications such as dismantling of nuclear reactors. The efficiency of a supersonic COIL is essentially a function of mixing specially in systems employing cross-stream injection of the secondary lasing (I2) flow in supersonic regime into the primary pumping (O21Δg) flow. Streamwise vorticity has been proven to be among the most effective manner of enhancing mixing and has been utilized in jet engines for thrust augmentation, noise reduction, supersonic combustion, etc. Therefore, a computational study of the generation of streamwise vorticity in the supersonic flow field of a COIL device employing a winglet nozzle with various delta wing angles of 5°, 10°, and 22.5° has been carried out. The study predicts a typical Mach number of approximately 1.75 for all the winglet geometries. The analysis also confirms that the winglet geometry doubles up both as a nozzle and as a vortex generator. The region of maximum turbulence and fully developed streamwise vortices is observed to occur close to the exit, at x/λ of 0.5, of the winglets making it the most suitable region for secondary flow injection for achieving efficient mixing. The predicted length scale of the scalloped mixer formed by the winglet nozzle is 4λ. Also, the winglet nozzle with 10° lobe angle is most suitable from the point of view of mixing developing cross-stream velocity of 120 m/s with acceptable pressure drop of 0.7 Torr. The winglet geometry with 5° lobe angle is associated with a low cross-stream velocity of 60 m/s, whereas the one with 22.5° lobe angle is associated with a large static and total pressure drop of 1.87 and 9.37 Torr, respectively, making both the geometries unsuitable for COIL systems. The experimental validation shows a close agreement with the computationally predicted values. The studies for the most suitable 10° lobe angle geometry show an observed Mach number of 1.72 with an improved mixing efficiency of 74% due to the occurrence of predicted streamwise vortices in the flow. 相似文献
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A chemical oxygen–iodine laser (COIL) that operates without primary buffer gas has become a new way of facilitating the compact integration of laser systems. To clarify the properties of spatial gain distribution, three-dimensional (3-D) computational fluid dynamics (CFD) technology was used to study the mixing and reactive flow in a COIL nozzle with an interleaving jet configuration in the supersonic section. The results show that the molecular iodine fraction in the secondary flow has a notable effect on the spatial distribution of the small signal gain. The rich iodine condition produces some negative gain regions along the jet trajectory, while the lean iodine condition slows down the development of the gain in the streamwise direction. It is also found that the new configuration of an interleaving jet helps form a reasonable gain field under appropriate operation conditions. 相似文献
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氧碘化学激光器(COIL)在化学反应条件下,由于光腔及扩压器的气流通道内存在残余化学反应放热,从而导致"热堵"现象发生,影响了扩压器的正常启动及光腔内超声速流场的流动品质。采用数值模拟方法对COIL光腔与超声速扩压器流道内的化学反应流场进行研究,对超声速扩压器插入段的长度、楔形体的数量级扩散段长度对化学反应流场的影响进行研究。数值模拟结果表明:通过优化插入段及楔形体长度、取消扩压器侧壁的半楔形体,改善了因化学反应放热对光腔及扩压器流场造成的不利影响。优化后,光腔内的流动不再受气流分离产生的斜激波的影响,扩压器二喉道内的分离现象消失,扩压器壁面的分离区减小,出口流动更加均匀,"热堵塞"现象消失。化学反应条件下的气流总压损失比冷流时提高约15%,光腔与扩压器的总压恢复系数为0.426,进出口的静压比为3.75,比优化前提高了约25%。 相似文献
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在薄层增益近似与非均匀加宽饱和增益系数条件下,用C-7程序对COIL非稳腔实验进行了数值模拟,计算所得结果对分析实验结果有一定参考价值。 相似文献
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提出了一种结构紧凑的长脉冲发生器,该发生器的螺旋型Blumlein线由内导体(含磁体)、螺旋型中筒和外导体(含磁体)构成,该结构实现了螺旋型Blumlein线和Tesla变压器的一体化。通过对螺旋型Blumlein线的波传输过程分析,给出了慢波系数、开关闭合电流、用于描述形成线闭合开关处界面上波行为的变量因子等参数的计算公式。采用PIC软件对螺旋型Blumlein线的部分波传输过程进行数值模拟,慢波系数等参数的模拟值与计算值基本相符。进行了恒阻抗负载下螺旋型Blumlein线的原理性实验,实验得到的负载波形与编程计算得到的波形基本吻合。 相似文献