共查询到17条相似文献,搜索用时 250 毫秒
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借助ANSYS/LS-DYNA软件对线型聚能切割器水下切割钢板性能的影响因素进行了数值模拟研究。重点分析了水介质、有无药型罩和带有空气槽对射流侵彻靶板的特性影响。结果表明:聚能槽内的水介质会阻碍射流的形成,严重影响切割性能;带有空气槽的切割器可以提供射流形成的空间,大幅提高射流的侵彻能力;通过对无药型罩切割器水下切割钢板的数值计算,得到的钢板侵彻深度可达15.3 mm,相比有药型罩时,无药型罩的切割深度有了很大提高,侵彻深度大约是有药型罩的3倍,接近空气中线型聚能切割器对钢板的切割深度17.2 mm。 相似文献
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为了实现聚能战斗部对水下目标的高效毁伤,在传统聚能战斗部的基础上设计了一种采用不同材料的球缺罩与偏心亚半球形罩组合的聚能战斗部。阐述了复合材质组合式聚能战斗部的结构设计及作用原理,利用有限元软件AUTODYN数值模拟了其成型及侵彻水下靶板的过程,并与传统的偏心亚半球缺式和单一材质组合式战斗部的毁伤效果进行了对比。研究表明,复合材质组合式战斗部形成的前级杆式射流侵彻水介质过程中可以为后级杆式射流开辟无耗能通道;在相同炸高下,侵彻相同厚度的水介质与靶板后,与传统杆式射流相比,复合材质杆式射流的动能衰减率最小,剩余动能提升了28.59%。该复合材质组合式聚能战斗部可以实现对水下目标的高效毁伤。 相似文献
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《工程爆破》2022,(1)
通过对线型聚能爆炸切割器的高速碰撞问题建立不可压缩流体模型,推导获得了爆炸切割射流参数的解析解,将之与聚能破甲理论结合,详细分析了爆炸切割器的设计要点。文中系统地说明了线型聚能切割爆破的切割深度、切割器设计炸高、聚能罩最佳顶角、聚能罩材料等与切割器参数的关系。进而利用所建立的流体聚能切割理论模型,对聚能切割器顶部同步起爆、沿顶部线性和外表面高速起爆问题都进行了理论解析和研究,分析了各种起爆方式的切割射流与破甲特点,以及对切割器参数设计的影响等。还根据滑移爆轰、等容爆轰、正向起爆对飞片驱动能力的对比分析,结合所建立的聚能切割理论,说明了高速起爆可以提高切割能力的原理。通过分析对比各种装药质量比下飞片的爆炸能量利用率,指出了爆炸切割器设计药量的选取原则。对于复杂的三维爆炸聚能切割理论问题,笔者尽量采用简洁直观的数学方法进行理论推导,着重对物理概念的阐述与分析,以求对线型聚能爆破的理论和技术发展起到促进作用。 相似文献
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为了解决传统基于网格的数值方法在模拟线性聚能射流问题时因大变形而导致网格畸变使计算难以进行的问题,本文通过自编程实现的光滑粒子法(SPH)对不同药型罩线性聚能装药射流形成及其侵彻金属靶板的过程开展了数值模拟研究,所实现的算法可以为线性聚能射流数值模拟研究提供新途径。本文所开展的研究首先基于已有的线性聚能射流试验模型进行模拟分析,采用SPH方法有效实现了线性聚能射流的形成过程,数值模拟获得的射流头部速度与试验比对误差在10%以内。然后建立了装药质量、药型罩质量和装药横截面宽度相同的前提下不同药型罩线性聚能射流模型,数值模拟获得不同药型罩形成的射流特征以及侵彻金属靶板的开口宽度和侵彻深度随时间的变化规律。研究得到的不同药型罩线性聚能射流形成及后效侵彻规律可为线性聚能射流的设计提供参考。 相似文献
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以有机玻璃为对象,研究下方介质对爆炸切割脆性平板的影响。当有机玻璃平板下方介质为空气、水、橡胶板时,进行爆炸切割有机玻璃平板试验及仿真。结果表明:改变有机玻璃平板下方介质将对平板断裂情况造成影响,当下方介质为空气时,平板断裂情况中层裂效果是最明显的,射流侵彻及冲击断裂影响较小;当下方介质为水时,射流侵彻对平板断裂作用最大,层裂效果减小,获得的平板断裂切口更为整齐;当下方介质为橡胶板时,相比于下方介质为空气时层裂效果会有所减小,射流侵彻效果有所增加,同样会获得相对整齐的断裂切口。研究结果可以为实际工程中涉及不同介质时爆炸切割脆性材料提供参考。 相似文献
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Buoyant laminar jet diffusion flames are studied experimentally in an inverted configuration, where gaseous fuel-stream jets vertically downward into air. Flame shape, thermal structure, soot and stability behaviors are obtained until the blowoff limit is reached. By comparing with conventional jet flames, which are established when the fuel jets upward, the effects of buoyancy on laminar diffusion flames are analysed. Downward flame yields larger flame height, although the non-dimensional flame height increases linearly with the Reynolds number at nozzle exit, which is similar to upward flame. Possible reasons for the increased flame height include flow deceleration within downward buoyant flames and presence of more combustion products surrounded the jet stream, thus slowing mixing process between fuel and air. The different relative directions of buoyant flows and jet streams also result in different temperature distributions in downward and upward flames, and a stagnant interface produced by the balance between buoyant flow and jet stream is particularly observed downstream of downward flame. Downward flames contain more soot and the soot formation region is wider, which are mainly attributed to the modifications of flow field and soot path. In addition, downward and upward flames stabilize at different axial positions relative to the nozzle exit. Because of increased characteristic flame residence time, downward flames have higher blowoff limits. The downward jet flame provides an alternative configuration to upward jet flame in studying buoyant diffusion flames due to the different manifestations of buoyancy effects. 相似文献
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A. M. Grishin O. V. Matvienko Yu. A. Rudi 《Journal of Engineering Physics and Thermophysics》2008,81(5):897-904
A numerical simulation of convective swirling jets arising as a result of the rotation of a heated disk in an initially immovable
medium has been carried out. It is shown that in the case where a jet is swirled moderately, the flow is relaminarized and
the intensity of the heat and mass transfer in the convective jet decreases, which leads to an increase in the buoyancy force
and, consequently, an increase in the velocity of the flow. The air mass in the form of a cylindrical column-shaped vortex
rises above the disk to a large height and, in doing so, retains its individuality.
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Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 81, No. 5, pp. 860–867, September–October, 2008. 相似文献
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对碰撞射流通风在定风量系统下的供热特性进行了数值模拟,并且对不同送风口安装高度和送风温差下的室内温度场分布和热气流扩散距离进行了分析。结果表明:同一送风温差时,送风口高度越高,热气流扩散距离越短;同一送风口高度时,送风温差越小,热气流扩散距离越长,由温度分层引起的不舒适感就会减弱。 相似文献
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《工程爆破》2022,(5):28-34
为了提升线型聚能装药的切割能力,在锥形线型药型罩的基础上设计了一种新型柱-锥结合线型药型罩,并采用数值模拟软件ANSYS/ls-dyna对柱-锥结合线型药型罩、圆弧顶线型药型罩、锥形线型药型罩射流的形成及切割45号钢板的过程进行了数值模拟,通过对比3种结构药型罩形成射流的头尾部速度、拉伸断裂时间、对45号钢板的切割能力来确定设计方案的可行性。研究表明:柱-锥结合线型药型罩形成射流的头部速度最高,相对锥形线型药型罩提高了约12.6%,相对圆弧顶线型药型罩提高了约5.4%;而且柱-锥结合线型药型罩形成的射流拉伸性能较好,能量更高,对45号钢板的切割能力最强,相对圆弧顶线型药型罩提升了约26.7%,相对锥形线型药型罩提升了约58.8%。 相似文献
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E. I. Părău S. P. Decent M. J. H. Simmons D. C. Y. Wong A. C. King 《Journal of Engineering Mathematics》2007,57(2):159-179
A liquid jet follows a curved trajectory when the orifice from which the jet emerges is rotating. Surface-tension-driven instabilities
cause the jet to lose coherence and break to form droplets. The sizes of the drops formed from such jets are in general not
uniform, ranging from drops with diameters of the order of the jet diameter to droplets with diameters which are several orders
of magnitude smaller. This presentation details a theoretical investigation of the effects of changing operating parameters
on the break-up of curved liquid jets in stagnant air at room temperature and pressure. The Navier–Stokes equations are solved
in this system with the usual viscous free-surface boundary conditions, using an asymptotic method based upon a slender-jet
assumption, which is clearly appropriate from experimental observations of the jet. Nonlinear temporal simulations of the
break-up of the liquid jets using slender theory are also presented. These simulations based upon both a steady-trajectory
assumption, and the more general equations which allow for an unsteady trajectory, show all the break-up modes viewed in experiments.
Satellite-droplet formation is also considered.
A. C. King deceased. 相似文献
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激光和水射流是对陶瓷等易碎材料进行辅助打孔的传统方法,其设备存在大而复杂等缺点。加工陶瓷等易碎材料时,利用超声振动的带孔变幅杆的设备比起传统的利用激光和水射流的的设备更简易和小型化,因此,超声加工受到了人们的重视。文章对中心孔分别为柱形和锥形、外形为圆柱形的超声杆件,基于解析法推导了这两种孔型变幅杆的频率方程及性能参数表达式,分析了不同参量对其性能参数的影响,并利用有限元法计算了在谐振状态下这两种变幅杆的应力及振动位移沿轴向分布的规律。结果表明,在相同谐振频率及面积系数下,带孔变幅杆的放大系数大于实心圆柱杆的放大系数;锥形孔变幅杆的放大系数小于柱形孔变幅杆的放大系数,但前者应力曲线光滑且应力极大值较小。 相似文献