受电子束辐照的硬铝靶的喷射冲量耦合系数随能通量的变化规律

采用通光式传感法和直接测量特定时间间隔的探头原理，在闪光２号装置上进行了电子束辐照硬铝靶产生的喷射冲量耦合系数与能通量关系的研究。结果表明:在能通量为１１５～２４０Ｊ／ｃｍ２范围内，喷射冲量和亏损质量面密度都随能通量近似线性变化，而喷射冲量耦合系数随能通量增大而缓慢递增，并趋于一渐近值；硬铝产生喷射冲量的能通量阈值为４０Ｊ／ｃｍ２左右；喷射冲量值为８１～２１８Ｐａｓ，亏损质量面密度为３．１ １０－２～８．６１０－２ｇ／ｃｍ２，喷射冲量耦合系数为０．７０～０．９８Ｐａｓ／（Ｊ／ｃｍ　２）。     

LY12复合型断裂的实验研究

应用有限元方法和断裂实验对铝合金ＬＹ１２在Ｉ＋Ⅱ型复合载荷作用下的弹塑性断裂行为进行了研究，给出了复合型弹塑性断裂的Ｊ积分准则，结果表明：（１）不同复合型下启裂Ｊ积分值满足ＪＩｉ／ＪＩｃ＋ＪⅡｉ／ＪⅡｃ＝１，ＪＭＣ＝ＪＩｉ＋ＪⅡｉ的关系，随Ⅱ型分量增加，启裂的Ｊ积分值ＪＭＣ增加ＪＩＣ为ＪＩＣ的两部；（２）ＪＭＣ值与复合比满足ＪＭＣ＝Ｋ＾２Ｉ．ＪＩＣ／（Ｋ＾２１＋αＫ＾２ＩＩ）＋αＫ＾２Ｉ．ＪＩＣ／     

《小问题》上期解答

《小问题》上期解答答２８７．１．Ｊｃ＝Ｊ０－ｍｌ２＝１２－１６９π２ｍｒ２，本题为单自由度，取广义坐标θ．粗糙时：速度瞬心为Ｐ１，ＪＰ１＝Ｊｃ＋ｍＣＰ１２＝３２－８３πｃｏｓθｍｒ２．动能Ｔ＝１２ＪＰ１θ２＝１２３２－８３πｃｏｓθｍｒ２θ２．图３图...     

《小问题》上期解答

《小问题》上期解答答２８７．１．Ｊｃ＝Ｊ０－ｍｌ２＝１２－１６９π２ｍｒ２，本题为单自由度，取广义坐标θ．粗糙时：速度瞬心为Ｐ１，ＪＰ１＝Ｊｃ＋ｍＣＰ１２＝３２－８３πｃｏｓθｍｒ２．动能Ｔ＝１２ＪＰ１θ２＝１２３２－８３πｃｏｓθｍｒ２θ２．图３图...     

离子注入聚酰亚胺的摩擦磨损性能研究

用Ｎ＋和Ｆｅ＋分别对芳香聚酰亚胺薄膜进行了离子注入处理，考察了注入前后聚酰亚胺与５２１００钢对摩时的摩擦磨损性能．结果表明，这２种离子注入都可以降低聚酰亚胺与钢对摩时的摩擦系数和磨损，而且高剂量（１０１６ｉｏｎｓ／ｃｍ２量级）离子注入的效果比低剂量（１０１４ｉｏｎｓ／ｃｍ２量级）离子注入的好，尤以３×１０１６ｉｏｎｓ／ｃｍ２的Ｆｅ＋注入改性作用更好     

环氧树脂－SiO_2空心微球复合材料的Mie－GrUneisen方程

本文描述了三种不同密度（０．６，０．７６和０．９ｇ／ｃｍ￣３）的环氧树脂－ＳｉＯ＿２空心微球复合材料的Ｈｕｇｏｎｉｏｔ关系。讨论了上述材料以其相应的Ｈｕｇｏｎｉｏｔ关系作为参考方程的Ｍｉｅ－Ｇｒｕｎｅｉｓｅｎ方程，并与Ｐ－α模型进行了比较，结果相当一致。由此得出结论，在本文研究的压力范围内，Ｍｉｅ－Ｇｒｕｎｅｉｓｅｎ方程可应用于上述孔隙材料。     

构造活动地区工程构造稳定性研究

在０．６１×１０￣５Ｒｅ６．０１×１０￣５，０．９３Ｈ／Ｄ２．５０（Ｈ为波高，Ｄ为圆柱直径）的范围内实验研究了弹性圆柱在浪流联合作用下的流体载荷。通过测量柱表面压力，得到了脉动升力和阻力系数，并给出了Ｍｏｒｉｓｏｎ公式中的Ｃ＿Ｄ，Ｃ＿Ｍ值随Ｋｃ数的变化关系，实验结果表明：在浪流联合作用下的圆柱体，其流体载荷与雷诺数的变化密切相关，并且圆柱的振动对流体载荷也有影响。     

四种陶瓷材料与SUS304不锈钢的高温摩擦学特性研究

为了探索陶瓷与金属组合作为高温润滑材料的可能性，利用端面摩擦磨损试验机测定了４种陶瓷ＳｉＣ、Ｓｉ３Ｎ４、Ａｌ２Ｏ３和ＺｒＯ２与ＳＵＳ３０４不锈钢在室温至５００℃下的摩擦学性能．摩擦试验结果表明，ＳｉＣ、Ｓｉ３Ｎ４和Ａｌ２Ｏ３在低于２００℃时的摩擦系数稳定且都低于０．２，但在２００℃以上时的摩擦性能却都不稳定，摩擦系数在０．２－０．４之间；ＺｒＯ２在２００℃以下时的摩擦性能不稳定，而在２００℃以上时的摩擦系数低于６．２且较稳定。磨损试验结果表明，在４种陶瓷中ＺｒＯ２的磨损率最低［－２．６０×１０－９ｍｍ３／（Ｎ·ｍ）］，ＳｉＣ和Ｓｉ３Ｎ４的磨损率居中［分别为１．８０×１０－６ｍｍ３／（Ｎ·ｍ）和４．４０×１０－６ｍｍ３／（Ｎ·ｍ）］，Ａｌ２Ｏ３的磨损率最高［３．６４×１０－５ｍｍ３／（Ｎ·ｍ）］；分别与这４种陶瓷对磨的不锈钢的磨损率都高［１．４０×１０－５－４．５２×１０－５ｍｍ３／（Ｎ·ｍ）］．     

等离子体源离子渗氮1Cr18n19Ti奥氏体不锈钢磨损特性的试验研究

用等离子体源离子渗氮，即低能（１－３ｋｅＶ）、超大剂量（１０＾１９－１０＾２０ｉｏｎｓ／ｃｍ＾２量级）Ｎ＾＋注入－同步扩散改性技术，在２８０℃和３８０℃下处理１ｃＲ９Ｔｉ奥氏全不锈钢，获得了最大深度分别为１．６μｍ和１０．６μｍ，固溶Ｎ的最高原子浓度均约为２５％的Ｎ过饱和面心立方相（γＮ）改性层。销－盘磨损试验表明：在２ｍ／ｓ和较宽负荷范围（等效正应力０．２－２．８ＭＰａ）条件下，高硬主（ＨＫ０．     

等离子体源离子渗氮 1Cr18Ni9Ti 奥氏体不锈钢磨损特性的试验研究

用等离子体源离子渗氮，即低能（１～３ｋｅＶ）、超大剂量（１０１９～１０２０ｉｏｎｓ／ｃｍ２量级）Ｎ＋注入－同步扩散改性技术，在２８０℃和３８０℃下处理１Ｃｒ１８Ｎｉ９Ｔｉ奥氏体不锈钢，获得了最大深度分别为１．６μｍ和１０．６μｍ，固溶Ｎ的最高原子浓度均约为２５％的Ｎ过饱和面心立方相（γＮ）改性层．销－盘磨损试验表明：在２ｍ／ｓ和较宽负荷范围（等效正应力０．２～２．８ＭＰａ）条件下，高硬度（ＨＫ０．１Ｎ２２００）的γＮ相改性层具有较高的承载能力和较长的耐磨寿命．高度过饱和Ｎ在母相奥氏体中的固溶强化作用，是使等离子体源离子渗氮奥氏体不锈钢耐磨性提高的主要原因．     

湍流场中物质微元的形态特征及相应的模型

运用高速显微摄影方法对１０￣１…１０￣３ｕｍ尺度上的微观混和过程进行了实验观察，将物质微元的形态特征归结为片状与条状两类。在此基础上，提出了片状结构模型，将微观混和描述为片状微元上的收缩变形与分子扩散。分析表明，由于变形与扩散之间的相互作用，微元上分子扩散区的宽度将趋于某一尺度δ＝１２λＢ，从而使微元体积呈指数增长，ｖ～ｅｘｐ（ｓｆ）．微观混和对化学反应的影响可用Ｄａｍｋ６ｈｌｅｒ数Ｄａ来表征，模型能够正确模拟这种影响。     

跨声速激波边界层相互作用的被动控制

运用激波管风洞在Ｒ＿（ｅ∞／ｍ＝３×１０￣７，Ｍ＿∞＝０．７３２－０．８１７范围内，在厚度比为１２％的圆弧翼型半模型和厚度比为１４％的超临界翼型半模型上，对被动控制现象及其若干规律进行了实验研究。结果表明，不同空腔深度的开孔壁和导管连通壁均可对壁面激波与边界层的相互作用实现被动控制，使得沿以上两种模型表面的马赫数峰值、逆压力梯度和激波强度明显减小。这对于飞行器将起到减阻作用，如将这一原理和方法用于超、跨声速压气机内激波与边界层相互作用的控制，将提高压气机的效率和工作的稳定性。     

返回舱三维高超声速绕流及近尾迹流场数值模拟

为使返回舱安全、稳定、可靠地飞行，准确地计算其周围的复杂绕流流场，对飞船的初步设计是十分必要的。用Ｈａｒｔｅｎ－Ｙｅｅ的二阶迎风ＴＶＤ有限差分格式求解薄层Ｎ－Ｓ方程，模拟了返回舱三维高超声速流场，Ｍ＿∞＝７．３５，Ｒｅ＿∞＝７．５×１０￣５，α＝１０°、２０°。给出了详细的绕流结构，不同攻角、不同子午面上的物面压力分布与Ｍｏｓｅｌｅｙ和ｗｅｌｌｓ的实验数据进行了比较，符合较好。通过分析表明，在一定的攻角下，倒锥体上低压区压力的计算精度，对力矩系数及压心位置仍有明显的影响。     

并列弹性双圆柱在均匀流场中的流体激励力的研究

实验研究了并列弹性双圆柱体在均匀流场中的水动力特性，其中包括柱表面稳态及脉动压力系数，稳态阻力及升力系数，脉动阻力和升力系数，结果表明：Ｖ＿ｒ＞Ｖ＿（ｒｃ）时，柱的振动对其流体激励力有明显影响。     

Hydrodynamics and dilution of an oil jet in crossflow: The role of small-scale motions from laboratory experiment and large eddy simulations

Experimental results were presented for the release of diesel oil from a one-inch (2.5 cm) vertical pipe in a crossflow at 0.27 m/s. The ratio of jet velocity to crossflow speed was 5.0 and the Reynolds number based on jet velocity and pipe diameter was $7.1\times {10}^3$. In the experiments, the plume shape was photographed, and the oil droplets were measured at two vertical locations on the center axis of the plume. Acoustic Doppler velocimetry (ADV) data was also obtained and compared to numerical predictions. The plume was simulated using large eddy simulation (LES), and the mixture multiphase model. The impact of the oil buoyancy was captured by adding a transport term to the volume fraction equation. Using the rise velocity based on d₅₀ (volume-median) droplet size in the lower part of the plume allowed us to capture the lower boundary of the plume, but the estimated upper boundary of the plume penetrated less into the crossflow as compared to the experimental findings. However, using the rise velocity of the d₅₀ at the upper part of the plume allowed one to estimate the upper boundary of the plume. As the droplets are too small to be resolved by the LES, we could not use a systematic approach to allow the multiphase plume to spread to mimic the observations. Based on the simulation results, the interaction between the jet and crossflow yielded small-sized flow structures near the upper boundary of the plume. The wake vortices initiated from the leeward side of the plume showed an alternating vorticity pattern in the wake. The shear layer vortices were induced by Kevin-Helmholtz instabilities mostly on the windward side of the plume. The formation of counter rotating vortex pair (CVP) altered greatly the hydrodynamics of the jet from that of a vertical jet to manifest flow reversals in all directions. The formation of CVP is likely to enhance the mixing of chemicals and droplets within the plume.     

A method to compute ship exhaust plumes with waves and wind

Thermal and concentration transport models are implemented in CFDShip‐Iowa version 4.5, a semi‐coupled solver for air/water free surface flow (Int. J. Numer. Meth. Fluids 2008; 58 (6):591–624), to investigate the exhaust plume around ship superstructures. An incompressible, variable density approximation is implemented where the density can change in all governing equations due to temperature variations only. The thermal and concentration models are tested for the cases of steady and unsteady flow with thermal and solution transport in a 2D square cavity, and for a 3D thermal plume in an open environment, showing good agreement between computational results and experimental data. To test the method in an extreme motions condition, the exhaust plume of the ONR Tumblehome model DTMB 5613 is studied, showing complicated vortical structures in air including a pair of counter‐rotating vortices downstream of the stack for cross‐flow, and bended bird‐plume shape in the symmetry plane and varying arc‐shape in axial sections both for temperature and NO_x concentration fields. Effects of smoke exhaust speed and wind speed on the temperature and concentration distributions are studied. Finally, a smoke downwash computation is performed for a ship free to move in 6 degrees of freedom in a sea state 8 condition. Copyright © 2010 John Wiley & Sons, Ltd.     

高速飞行体尾喷焰辐射特性研究进展

本文对飞行器尾喷焰红外辐射特性理论计算的全貌作了系统的论述.讲述了国内外在这一领域的研究近况和国内所取得的成绩.特别对以原子分子理论为基础的物理力学方法研究尾喷焰辐射特性的重要性进行了论述.      

The dispersal processes within the tide‐modulated Changjiang River plume,China

The dispersal processes of the tide‐modulated Changjiang River plume, China, are studied by using a three‐dimensional hydrodynamical module of the COHERENS (A COupled Hydrodynamical–Ecological model for REgional and Shelf Seas). The model is driven by the river discharge and the M₂ tidal constituent. Modelled results show: (1) the fresh water, which forms the Changjiang River plume expanding southeastwards, is discharged mostly into the North Channel, the North Passage, and the South Passage; (2) the larger horizontal gradient outside the North Channel and the North Passage forms a strong plume front; (3) the Changjiang River plume is homogeneous vertically, and dispersing gradually within the computational domain, with an averaged propagating rate of 3.38 km/day, while the plume front is surface‐to‐bottom type, and trapped between ?10 and ?18m isobaths; and (4) both the plume length and the plume front intensity vary periodically. The maximum plume length occurs about 2 h after low slack water and the minimum plume length during high slack water. The maximum plume front intensity occurs during high slack water and the minimum plume front intensity during low slack water. Copyright © 2007 John Wiley & Sons, Ltd.     

Temperature spectra from a turbulent thermal plume by ultrasound scattering

This paper reports the results of a study on temperature inhomogeneities conducted on a thermal plume by using ultrasound scattering as a non-intrusive measurement technique. The plume rises from a metallic disk which can be heated up to 800 °C. The working fluid is air at atmospheric pressure. In the measurement technique, an incoming ultrasound wave is emitted towards the thermal plume. The incident wave is scattered because of non-linear couplings with the flow instabilities present in the measurement region. The scattered wave carries information about those flow instabilities. The technique allows for the retrieving of this information. The shape of the obtained spectrum of temperature fluctuations as a function of wave vector modulus is consistent with previous theoretical analysis. Three qualitatively different regions were identified: first, a production region characterized by a q² law; secondly, a region with behavior as per q⁻³ associated with a buoyancy region and; finally, a dissipation region associated with a q⁻⁷ law. These spectral regions characterize the energy transfers mechanisms among the length scales of flow investigated here. A coefficient of anisotropy γ was defined to analyze anisotropic features of the flow.     

三维气泡羽流的Kobus理论的扩展与评判

本文用已有的一些典型实验数据对三维气泡羽流的Kobus理论进行了全面检验。导出了计算Kobus理论中所包含的全部经验常数的公式,使得Kobus理论的实际应用更加方便。并对Kobus理论进行了评判。