共查询到19条相似文献,搜索用时 125 毫秒
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为了验证理论分析得到的圆锥形喷管在单脉冲条件下的激光推进能量相似律,用2维轴对称辐射流体动力学方法,计算得到了不同构形的推进性能参数,分析了锥角、长度、无量纲因子、入射激光能量对冲量、冲量耦合系数的影响。计算揭示的激光推进能量相似律合理,在理论模型可以描述的范围内,其定性规律与理论分析、实验结果之间相互印证。结果表明:当锥角固定时,冲量和冲量耦合系数随无量纲因子先增大后减小,极大值对应的无量纲因子仅与气体比热比相关;当无量纲因子固定时,冲量随入射激光能量增加而增大,冲量耦合系数受激光能量的影响很小,冲量和冲量耦合系数均随锥角增大而单调减小。 相似文献
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脉冲激光与碲镉汞相互作用时的冲量耦合 总被引:3,自引:0,他引:3
在激光功率密度为4.0×108~5.0×109Wcm-2的范围内,用冲击摆测量了NdYAG脉冲激光(波长为1.06μm,脉宽为10ns)辐照大气中不同面积的HgCdTe样品时的冲量耦合系数。从理论上建立了等离子体爆轰模型,对激光结束后等离子体的膨胀过程进行了比较详细的描述,用此模型计算了不同能量的脉冲激光与不同面积的HgCdTe相互作用时的冲量耦合系数,计算值与测量值符合得较好。 相似文献
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利用激光清除空间碎片被认为是一种可行手段,冲量耦合系数是数值计算空间碎片清除效果的重要参数。建立了激光烧蚀冲量耦合系数解析计算模型,引入电离度参数,将气化机制与等离子体机制两种机制下的冲量耦合系数解析计算模型联系起来,建立统一的耦合系数解析模型。以空间碎片常见材料Al为例,计算得到冲量耦合系数、电离度、激光功率密度三者之间的变化关系。随着激光功率密度的增加,气化机制逐渐向等离子体机制过渡,电离度增加,直至完全电离,冲量耦合系数先增加后减少,并且在等离子机制占主导情况下达到最优冲量耦合。 相似文献
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采用单脉冲激光进行了大气环境下激光烧蚀小钢珠实验,得到其推进效应参数,发现并分析了钢珠在不同放置位置(焦前与焦后)时不同的物理现象;为了得到一系列定量实验数据,采用自行研制的激光冲量靶仪进行了单脉冲激光烧蚀推进效应实验测试,得到了不同环境条件、不同靶材料的激光推进效应参数,并与国外的实验数据以及数值计算结果进行了比较。实验表明,靶材料和激光功率密度是影响冲量耦合系数的主要因素,冲量耦合系数随环境气压的降低而升高。 相似文献
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保持CO2激光的单脉冲能量为61.4~64.6 J,采用高精度冲击摆系统进行了不同气压下吸气模式激光推进冲量耦合系数的实验测试,分析了对应的高度特性。结果表明:气压为2.8×104~1×105 Pa,即距离地面0~10 km时,冲量耦合系数大约3.5×10-4 N·s·J-1,上下波动幅度低于5%;气压低于2.8×104 Pa,即高度大于10 km时,冲量耦合系数呈二次曲线显著下降;当气压降至1×103 Pa,即距离地面约31 km高度时,耦合系数仅为9.7×10-5 N·s·J-1。 相似文献
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结合辐射输运方程,在流体力学方程组的能量方程中加入包括空气吸收的激光能量以及高温气体向周围辐射损失的能量源项,转化为辐射流体力学方程组,建立了用于模拟吸气式激光推进中能量沉积过程的物理力学模型和计算方法。该辐射流体力学计算程序可以很好地模拟激光能量沉积过程中空气对激光能量的吸收、等离子体对激光的屏蔽作用以及激光维持的爆轰波的传播规律,计算得到激光能量的沉积效率约为57%,激光维持的爆轰波的传播速度与同等条件下的理论和实验结果吻合得较好。 相似文献
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Yasir Jamil Humaima Saeed M. Raza Ahmad Shakeel Ahmad Khan Hashim Farooq Muhammad Shahid K. M. Zia Nasir Amin 《Applied Physics A: Materials Science & Processing》2013,110(1):207-210
Laser ablation propulsion is a form of beam-powered propulsion in which a pulsed laser ablates a target material thus producing thrust. We report in this work the measurements of various parameters related to laser-induced micropropulsion in toluene diisocyanate-based polyurethane polymer, aluminum and Co–Ni ferrite. The targets were irradiated by a Q-switched pulsed Nd–YAG laser at 1064 nm (pulse duration 5 ns) under atmospheric conditions. A contact-free optical triangulation method was used to measure the laser ablation induced thrust in the samples. The measurements and calculations depict that Co–Ni ferrite is better in terms of critical propulsion parameters C m and I sp. It has been observed that the propulsion parameters depend on the energy per pulse of the incident laser beam. 相似文献
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The Process of a Laser-Supported Combustion Wave Induced by Millisecond Pulsed Laser on Aluminum Alloy 下载免费PDF全文
《中国物理快报》2016,(1)
We study the process of a laser-supported combustion wave(LSCW) when an aluminum alloy is irradiated by a millisecond pulse laser based on the method of laser shadowgraphy.Under the condition of different laser parameters,the obtained results include the velocity,ignition threshold of LSCW and the variation law.The speed of LSCW increases with the laser energy under the same irradiation laser pulse width,and the speed of LSCW reduces with the increase of the laser pulse width under the same irradiation laser energy.Moreover,the ignition time of LSCW becomes shorter by increasing the laser number of the pulse and is not effected by changing the frequencies,when keeping the laser pulse width and energy unchanged.The results of the study can be applied in the laser propulsion technology and metal surface laser heat treatment,etc. 相似文献
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Z. Y. Zheng L. Gao H. Gao J. Xing X. W. Wu 《Applied Physics A: Materials Science & Processing》2014,117(3):1577-1581
A “comb” structure of beam intensity distribution is achieved to measure target displacements at the micrometer level in laser plasma propulsion experiments. Compared with single-beam and double-beam detection, the “comb” structure is more suitable for a thin film targets with a velocity lower than 10?2 m/s. Combined with a light-electric monitor, the “comb” structure can be used to measure a velocity range from 10?3 to 1 m/s. Using this “comb” structure, the coupling coefficient of aluminum ablated by nanosecond pulse laser in air is determined and compared. The results indicate that this “comb” structure is an effective experimental approach. 相似文献
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Bing Han Yun-Xiang Pan Ya-Li XueJun Chen Zhong-Hua ShenJian Lu Xiao-Wu Ni 《Optics and Lasers in Engineering》2011,49(3):428-433
Laser propulsions of six kinds of propelled objects in water and air are studied in this paper. The kinetic energy and momentum coupling coefficients gained by the objects after implementation of single laser pulses are investigated experimentally. It is shown that the propulsion effects are better in water than in air. Both in water and in air, the propulsion effects are better if there is a cavity on the laser irradiated surface of the object, and a hemispherical cavity works better than a 90°-conical cavity. A concept of equivalent reference pressure is proposed in this paper. It means that the asymmetry in the liquid induced by a rigid boundary near a spherical or nonspherical oscillating bubble can be approximated as the perturbation induced by a compressive stress wave passing through a bubble in the infinite static liquid. Thus, the collapse time and the pressure surrounding the nonspherical collapsing bubble can be estimated based on the maximum velocity of the liquid jet tip. Experiments also show that cavitation with oscillations and collapse can be induced at the object-water interface on the outside surface of the object head by the penetrating intensive stress wave and the elastic deformation of the object head. The bulging velocity of the object surface is calculated based on the propagation theory of stress waves at medium interfaces. 相似文献
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选择含能聚合物聚叠氮缩水甘油醚(GAP)作为激光烧蚀微推力器的工质,分析了红外染料掺杂对激光烧蚀GAP工质推进性能的影响.通过对比掺杂红外染料GAP在不同激光功率密度、掺杂浓度、靶材厚度和激光烧蚀模式下的推进性能数据和烧蚀羽流,初步探索了掺杂红外染料GAP工质的推进性能优化方式.实验结果表明:透射式激光烧蚀模式下,激光能量的指数衰减特性和掺杂红外染料GAP的强黏性使得烧蚀羽流中易存在未充分烧蚀的工质; GAP的推进性能受红外染料掺杂浓度和靶材厚度的综合影响,当靶材厚度与激光吸收深度接近时,靶材充分吸收激光能量使中心烧蚀区达到化学能释放的温度阈值,同时沿激光传播方向未充分烧蚀的质量最少,此时推进性能达到最优值.反射式下掺杂红外染料的聚合物的激光烧蚀过程遵循"先吸收激光能量先喷射"的规律,工质分解充分,推进性能优于透射式. 相似文献
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在激光驱动飞片研究中,飞片的加速特征是需要认识的关键问题之一。设计了强激光作用金属膜驱动飞片实验,采用聚偏氟乙烯(PVDF)压电薄膜测量了飞片到达不同距离的时间,计算得到飞片速度和加速度,分析激光能量对飞片加速性能的影响。基于Gurney能理论,建立了激光驱动飞片速度的计算模型,根据实验结果获得了激光能量损失系数和有效吸收系数,分析了激光能量和膜体厚度对飞片速度的影响。实验结果表明:不同激光能量下飞片的加速特征基本相似,激光能量变化对飞片的加速时间影响较小; 激光能量较大的情况下,膜体厚度对飞片最大速度、能量耦合系数的影响更显著; 当膜体超过一定厚度时,能量耦合系数不再增加。 相似文献
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