小长径比张开式尾翼弹气动力三维数值模拟

基于有限体积法计算了一种具有小长径比、大展弦比张开式尾翼弹在有攻角超声速粘性流动时的气动特性,分析了该弹周围的流场特性。研究结果表明,该尾翼弹的阻力系数和升力系数均随着马赫数增大而减少,随攻角增大而增大,且呈线性变化;当马赫数从2增大到4时,攻角从4°增大到12°,压心位置变化范围占全弹长的10.3%。     

管式发射巡飞弹的气动特点及设计

讨论了管式发射巡飞弹的气动特点和设计,分析了折叠翼的低雷诺数高升力翼型的气动特性、设计方法以及弹翼的折叠设计,并分析了柔性充气翼的发展、优缺点、气动特性以及目前存在的技术难题.研究结果表明,封装后的充气翼不会破坏机翼结构的整体性,体积降为展开体积的1/10,避开了传统飞行器复杂的折叠结构,质量也大为减轻.分析结果表明充气翼的发展优势以及巡飞弹气动一体化总体设计技术的重要性.     

三维偏转头弹箭流场结构与气动特性研究

基于分离涡模拟(DES)方法及平流上游分割方法(AUSM)格式,利用Fluent软件对偏转头弹箭在零攻角和不同偏转角时的超声速流场和气动参数进行了数值模拟。比较偏转头弹箭和普通弹箭的流场结构发现,二者头部激波结构差异较大,但下游流场几乎相同;该流场结构提高了弹箭的气动特性。偏转头对气动力系数的影响主要表现为增加弹箭头部的升、阻力系数,且升力系数增量大于阻力系数。在零攻角情况下,偏转头弹箭具有一定升力,该升力可有效降低维持其飞行高度所需的驱动力,提高偏转弹的机动性。     

三维偏转头弹箭流场结构与气动特性研究

基于分离涡模拟(DES)方法及平流上游分割方法(AUSM)格式,利用Fluent软件对偏转头弹箭在零攻角和不同偏转角时的超声速流场和气动参数进行了数值模拟。比较偏转头弹箭和普通弹箭的流场结构发现,二者头部激波结构差异较大,但下游流场几乎相同;该流场结构提高了弹箭的气动特性。偏转头对气动力系数的影响主要表现为增加弹箭头部的升、阻力系数,且升力系数增量大于阻力系数。在零攻角情况下,偏转头弹箭具有一定升力,该升力可有效降低维持其飞行高度所需的驱动力,提高偏转弹的机动性。     

两种典型尾翼形状对无伞末敏弹气动特性的影响

为研究尾翼形状对双翼无伞末敏弹减速导旋性能的影响,分别对平板尾翼和S-C形尾翼结构末敏弹的气动特性进行研究。基于计算流体力学方法,获得了末敏弹气动外形的流场特性、表面压力分布和阻力系数、升力系数和转动力矩系数随攻角变化的规律。通过自由飞行试验对平板尾翼和S-C尾翼末敏弹进行了动态气动特性研究。数值计算结果显示,平板尾翼和S-C尾翼模型阻力系数在6～9间,其增阻效果明显;两模型升力系数均呈负线性变化,尾翼形状对升力系数影响较小;尾翼形状对转动力矩系数影响明显,平板尾翼几无转动力矩产生,S-C尾翼转动力矩相对较大并随攻角增加而减小。自由飞行试验表明,S-C尾翼结构自由飞行状态下增阻效果好于平板尾翼,并可使弹体获得转动力矩而维持稳定转速,能够实现稳态扫描运动。平板尾翼末敏弹自由飞行稳定性差。     

折叠式主弹翼气动特性研究

针对制导航弹的气动设计要求,设计了一种前后折叠式弹翼.并使用数值计算和工程计算方法研究前后折叠式弹翼、钻石背弹翼以及后折前张式弹翼的气动特性.计算结果表明:前后折叠式弹翼与钻石背弹翼升力系数在攻角较小时接近,在攻角较大时,前后折叠式翼的升力系数大于钻石背弹翼;前后折叠式弹翼的升阻比最大;后折前张式弹翼的外形滚转阻尼力矩系数最小;钻石背弹翼的外形滚转阻尼力矩系数最大.     

受电弓设备对列车气动特性影响的风洞试验

为了充分了解和掌握在强侧风作用下受电弓设备(受电弓和导流罩)对高速列车气动性能的影响,通过风洞试验对强侧风下高速列车运行时的气动性能进行测量和分析.实验结果表明:当侧滑角小于15°时,列车模型阻力系数随着侧滑角的增大而增加,当侧滑角为15°时,阻力系数出现拐点,拐点后阻力系数开始下降,其侧向力系数的绝对值和升力系数随着侧滑角的增大而增加;受电弓设备对头车的影响较小,但可使中车侧向力系数的绝对值及阻力系数明显增加,使尾车的阻力系数明显减小,而侧向力系数明显增加;受电弓设备中“浴盆”式导流罩对高速列车阻力系数的影响强于“挡板”式导流罩的影响,但对升力系数及侧向力系数的影响弱于“挡板”式导流罩的影响.     

次口径非对称鸭舵对弹道修正弹气动特性的影响

为研究次口径非对称鸭式布局的弹道修正弹气动特性,基于网格装配的方法建立了修正弹气动力计算模型,并通过风洞试验对超音速条件下的计算结果进行验证,从鸭舵绕流、升阻系数和滚转力矩方面分析鸭舵对修正弹气动参数的影响. 研究结果表明,次口径非对称鸭舵使修正弹相比传统弹丸阻力系数增加达14%,但操纵舵引起的升力使弹丸的射程衰减率降至10%. 鸭舵安装角对修正弹升力影响效果大于阻力. 通过工程简化模型将升力分解为操纵舵提供的升力和由于鸭舵的存在使弹体产生的升力两部分,拟合出鸭舵对弹体升力的干扰因子.      

钻石背弹翼外形参数对气动特性的影响

定义了描述钻石背弹翼平面形状的2个几何参数,采用模块化方法设计了一组风洞实验模型,进行了风洞测力实验,研究了前、后翼条高度差及其间距对钻石背弹翼气动特性的影响.实验结果表明,前翼条高、后翼条低配置的钻石背弹翼的升力、升阻比比前翼条低后翼条高配置的钻石背弹翼的升力、升阻比大;前后翼条间距对钻石背弹翼气动特性的影响较小.     

含升力偏置的共轴刚性旋翼配平与响应分析

建立考虑升力偏置的共轴刚性旋翼气弹配平计算方法。在单旋翼气弹计算方法基础上,引入考虑双旋翼气动干扰的入流模型,针对大反流区气动力计算和大前进旋翼气弹配平计算进行相应修正,最终集成考虑升力偏置的共轴刚性旋翼气弹配平计算方法,并开展考虑升力偏置的共轴双旋翼气弹配平分析。分析提前操纵角、升力偏置、前进比因素对双旋翼配平和响应的影响,研究表明在中等前进比时,下旋翼拉力略大于上旋翼,气动效率优于上旋翼。大前进比下桨尖响应曲线呈现2阶特性而增加升力偏置使得响应曲线逐渐为1阶曲线变化,且提前操纵角对双旋翼操纵和桨尖间距均无影响。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that