共查询到20条相似文献,搜索用时 203 毫秒
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《高压物理学报》2018,(6)
在环形聚能装药结构中,单锥罩结构形成的射流中间有堆积现象,断裂前射流拉伸长度有限,而双锥罩射流兼顾了上锥小锥角形成高头部速度,下锥大锥角增大射流有效质量的优点,形成的射流更加细长,头部速度高且不易断裂。基于环形切割聚能装药战斗部,综合考虑上锥角大小、上锥罩占药型罩高的比例、药型罩的高度以及药型罩壁厚对射流侵彻能力的影响,并基于灰关联理论对双锥罩环形聚能装药的优化提供依据,通过数值仿真,研究表明:上下锥角对射流成型影响最大,通过比较,当上锥罩为34°、上锥占罩高比例为40%、药型罩高度为70mm、药型罩壁厚为5mm时,形成的射流头部速度高,且在空气中能够稳定飞行。相比单锥罩结构,双锥罩射流细长,在空气中飞行时间长,对靶板的侵深大于单锥罩射流。 相似文献
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在弹道测量、高速飞行物碰撞实验(如太空的‘垃圾’碎片对飞行的卫星、飞行舱的损害研究)及其它的类似实验中,需要准确测量飞行物碰撞前的一些状态:如速度、飞行姿态、断裂等情况,并且希望得到在碰撞前很短的距离处测量的数据。那么,在使用X光的阴影照相技术中有关X光机的触发问题就显得更加重要;如果X光机提前触发,此时飞行物还未进入照相区域或者离碰撞区的距离还远,则记录不到弹丸的X光图像或者位置不理想而造成数据不够准确;如果X光机延迟过多触发,则因已碰撞而无法获得碰撞前的状态参数:所以,X光机的触发时刻必须准确才能保证获得物体在希望位置处的X光阴影图像,并且降低实验成本。 相似文献
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通过分析应力波在橡胶复合靶板中的传播特性,研究了复合靶板上各层质点速度在应力波作用下的变化情况,分析了应力波在橡胶复合靶板对射流干扰中的作用,结合射流在空气中的断裂模型,提出了射流在复合靶影响下的断裂模型;分析了橡胶夹层厚度对复合靶板抗射流侵彻性能的影响;通过脉冲X光照相技术和穿深实验,研究了橡胶夹层厚度不同时,在射流以68°倾角侵彻下,橡胶复合靶板对56 mm口径基准成型装药射流的干扰情况及射流的剩余侵彻能力。研究结果表明:理论分析与实验结果相吻合;橡胶复合靶板对射流有很好的干扰作用;在满足结构效应的情况下,随着天然橡胶夹层厚度的增加,应力波对射流的干扰能力降低,射流的变形程度减小,复合靶板的防护能力降低。 相似文献
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超音喷流啸音发声机理的实验研究 总被引:5,自引:0,他引:5
啸音是超音速喷流噪声的三大成分之一,其特点是向上游传播的离散纯音,被认为是飞机部件声疲劳的重要因素之一。但到目前为止,啸音仍是喷流噪声研究中理解最少、预测能力最低的成分,研究表明这主要是因为啸音受环境的影响很大,如啸音的强度就受到喷流马赫数、喷流温度、喷嘴唇口厚度以及形状等的影响。本文通过实验研究了在超音速喷流情况下喷嘴唇口厚度对啸音幅值、模态等的影响。实验结果表明,随着喷嘴厚度的增加,啸音的幅值增加达到了10 db以上。啸音的频率则随着唇口厚度的增加有所减小。 相似文献
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It has been found experimentally that broad band jet noise can be amplified by a pure tone excitation as much as 6 to 7 dB. The jet noise amplification effect takes place at sound pressure levels which are present in real aircraft engines. The experimental investigation was restricted to a cold jet at high subsonic Mach numbers excited by a plane sound wave coming from inside the nozzle. Based on a simplified mathematical model an attenuator has been constructed which is able to reduce the jet noise amplification significantly. 相似文献
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A visual study of underexpanded plasma jet was conducted to reveal the detailed behavior in the strong magnetic field. The
images of the jet were taken by a digital single-lens reflex camera through viewing windows. The distribution of optical intensity
obtained from the raw data was compared to that of the typical emission line intensity. The profile of the optical intensity
agrees well with that of the emission intensity. It is illustrated that the typical structure of underexpanded jet such as
Mach disk is also affected obviously by the magnetic field. The radial distribution of number density was determined by using
the image analysis based on the Abel-inversion. The converted data clarify the jet behavior that is hidden on the ordinary
observation. The density obtained from numerical analysis for a simple gas was also compared with the number density. It is
confirmed from the comparison with numerical results that the radial profile of number density can be utilized for understanding
the plasma jet behavior under the strong magnetic field. 相似文献
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The present study numerically investigates liquid-jet characteristics of acoustic cavitation during emulsification in water/gallium/air and water/silicone oil/air systems. It is found that a high-speed liquid jet is generated when acoustic cavitation occurs near a minute droplet of one liquid in another. The velocity of liquid jet significantly depends on the ultrasonic pressure monotonically increasing as the pressure amplitude increases. Also, the initial distance between cavitation bubble and liquid droplet affects the jet velocity significantly. The results revealed that the velocity takes maximum values when the initial distance between the droplet and cavitation bubble is moderate. Surprisingly, the liquid jet direction was found to depend on the droplet properties. Specifically, the direction of liquid jet is toward the droplet in the case of water/gallium/air system, and vice versa the jet is directed from the droplet in the case of water/silicone oil/air system. The jet directionality can be explained by location of the high-pressure spot generated during the bubble contraction. 相似文献
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A. A. Kornilova V. I. Vysotskii N. N. Sysoev N. K. Litvin V. I. Tomak A. A. Barzov 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2010,4(6):1008-1017
The radiation processes associated with a supersonic water jet exhausting from a narrow channel are considered. It has been
found for the first time that the output of the channel and the initial portion of the jet are sources of intense X-radiation,
generation of which is related to cavitation processes in the water jet bulk and subsequent excitation of shock waves. The
frequency of X-radiation depends on the types of atoms on a radiating surface (for a jet, it is water; for a channel, the
metal atoms on the surface) and increases with the charge of atoms. The total X-ray activity of an experimental setup in the
mode of jet exhaust reaches 0.1 Ci. It is found for the first time that the impact of shock acoustic waves, which are formed
in the air as a result of cavitation jets of water, on distant screens leads to the generation of a quasi-coherent directional
X-ray emission from the back side of these screens. The spatial parameters of this radiation depend on the shape and cross
section of the screen and the spatial characteristics of the shock wave. 相似文献
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Elena Bruna 《The European Physical Journal C - Particles and Fields》2009,62(1):133-137
The measurement of jet fragmentation functions in p+p collisions at 200 GeV is of great interest because it provides a baseline
to study jet quenching in heavy-ion collisions. It is expected that jet quenching in nuclear matter modifies the jet energy
and multiplicity distributions, as well as the jet hadrochemical composition. Therefore, a systematic study of the fragmentation
functions for charged hadrons and identified particles is a goal both in p+p and Au+Au collisions at RHIC. Studying fragmentation
functions for identified particles is interesting in p+p by itself because it provides a test of NLO calculations at RHIC
energies. We present a systematic comparison of jet energy spectra and fragment distributions using different jet-finding
algorithms in p+p collisions in STAR. Fragmentation functions of charged and neutral strange particles are also reported for
different jet energies. 相似文献
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在Re=5×106的条件下,分别在S809翼型前缘点附近不同位置处设置离体射流装置,改变射流动量的大小和射流口宽度,探究其对S809翼型气动性能的影响。并通过流场分析,研究这种流动控制手段有效的物理机理。结果表明:在射流装置位置和射流口宽度固定时,射流动量的大小对控制效果影响显著;在S809翼型表面附近设置微小离体射流装置后,即使关闭射流(射流动量为零时),也具有一定的流动分离控制效果;当射流动量逐渐增大时,射流能明显的减小流动分离泡的大小,降低阻力系数,同时可以有效提升升力系数,使得翼型的气动性能得到进一步显著提升。值得指出的是,射流口宽度与射流装置的位置对流动控制效果也具有一定的影响。 相似文献