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Product correlators are being developed and implemented as a means of improving the guidance capability of tactical missiles. Analytical and experimental results are presented for maximizing the pull-in range of product area correlators via investigation of the discriminator curve of the correlator. The maps used in the correlation are assumed to be sample functions from two-dimensional, zero-mean, stationary Gaussian random processes. To obtain closed-form results, the additional assumption of a Gaussian correlation function is made. These analyses and results should be applicable to a wide range of correlation systems. Implications of these results as they pertain to missile guidance are discussed. 相似文献
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The numerical simulation of the flow for the VFE-2 delta wing configuration with rounded leading edges is presented using the Cobalt Navier–Stokes solver. Cobalt uses a cell-centered unstructured hybrid mesh approach, and several numerical results are presented for the steady RANS equations as well as for the unsteady DES and DDES hybrid approaches. Within this paper the focus is related to the dual primary vortex flow topology, especially the sensitivity of the flow to angle of attack and Reynolds number effects. Reasonable results are obtained with both steady RANS and SA-DDES simulations. The results are compared and verified by experimental data, including surface pressure and pressure sensitive paint results, and recommendations for improving future simulations are made. 相似文献
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In automatic radar detection, digital integration of the envelope detector outputs is often used as a good approximation to the optimum. This requires quantizing the envelope detector outputs. In this paper, quantizer structures for narrowband signal detection are considered. Quantizer characteristics are derived to optimize performance as measured by the detector efficacy?an asymptotic performance measure. Asymptotic and finite sample performance results are presented. The results obtained are not limited in their application to Gaussian noise only, although this important case is given specific consideration. 相似文献
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应用FENSAP-ICE结冰计算软件,对NACA0012翼型进行了流动特性、水滴撞击特性以及冰型生成过程的计算;同时,对结冰前后的翼型进行气动力特性计算对比分析,其中包括升力特性对比、阻力特性对比、流场细节分析以及压力系数分布对比。计算结果表明:翼型前缘结冰后,导致翼型前缘气流提前分离,最大升力系数、失速攻角大幅减小,... 相似文献
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本文研究不同半径圆柱诱导CH4/空气预混燃烧流场。采用保自由流5阶WENO格式求解贴体坐标变换后的多组分Euler方程,用基元反应模型描述CH4/空气燃烧。不同于标准WENO格式通量构造方法,该WENO格式数值通量由方程的解进行WENO插值得到,在曲线坐标系下具有保自由流性质。首先给出了保自由流WENO格式精度和保自由流的数值验证,然后计算圆柱诱导CH4/空气预混气燃烧流场,并考察不同半径圆柱的影响,给出燃烧流场压力与温度等值线和云图、压力和温度沿过驻点线分布。结果表明:在考核计算结果网格无关性基础上,该WENO格式可准确地捕捉激波和火焰阵面形状、激波和火焰面驻点距离,得到的计算结果和文献结果相符。增大圆柱半径,激波和火焰面被推向来流方向,激波和火焰面之间距离也减小。和TVD格式相比,5阶WENO格式采用四分之一的网格数可得到近似相同的计算结果。 相似文献
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大展弦比复合材料机翼的非线性颤振分析 总被引:4,自引:0,他引:4
大展弦比机翼在气动力作用下产生较大变形,颤振速度和颤振频率随之发生明显变化,线性理论难以获得比较合理的解答。综合考虑了结构几何非线性、气动非线性和材料各向异性对机翼运动状态的影响,将复合材料机翼建模为非线性薄壁单闭室截面梁,建立机翼的运动方程,并使用小扰动分析的方法得到机翼在平衡位置附近的振动方程。采用Theodorsen非定常气动理论构建气动模型,获得机翼在平衡位置附近的非线性颤振方程,并利用v-g法判定机翼颤振稳定性。通过算例演示了一些非线性颤振的特点,讨论了铺层角、展弦比、机翼线密度等参数对颤振速度的影响,并与线性理论得到的结果进行对比。 相似文献
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主要讨论了测量参数间的时间延迟对飞机气动导数辨识结果的影响。通过对飞机仿真数据的计算表明,为了保证气动导数辨识的准确性,必须对测量参数间的延迟时间作一定的限制。结果表明,飞机的主要导数对时间延迟不敏感,而一些小值导数则较敏感。文中还根据实际计算经验对测量参数间的延迟时间给出了适当的限制。这些结果可为工程应用提供理论参考。 相似文献
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Rainbow型压电单膜片换能结构负载电压和输出功率分析 总被引:4,自引:1,他引:3
给出了一种多方向振动能量收集装置的设计结构.为研究Rainbow型压电单膜片换能结构材料、尺寸参数、负载电阻对其输出功率的影响,根据压电材料的机电耦合方程和弹性力学理论,建立了Rainbow型压电单膜片换能结构负载电压及输出功率的理论模型.对所建理论模型进行了数值计算和验证测试,理论计算结果及测试结果具有较好的一致性,... 相似文献
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行星减速器油膜均载的分析计算 总被引:1,自引:0,他引:1
运用流体动力润滑理论分析了油膜均衡行垦齿轮间载荷的机理,解释了共转滑动轴承的动态特性。利用数值方法求解了Revnolds方程。计算结果和试验结果有良好的一致性,并表明:共转滑动轴承的油膜柔度随载荷的增大而减小;随轴承间隙的增大而增大;随转速的增大而减小。 相似文献
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基于旋转轴向阵列的风扇宽频噪声实验 总被引:2,自引:0,他引:2
航空发动机降噪研究迫切需要一种叶轮机械管道内宽频噪声测量方法来指导降噪设计。本文通过对阵列测量的声压信号进行互相关分析,得到管道内顺流和逆流传播的模态声功率结果。安装在风扇实验台进口段的传声器阵列由2排周向间隔180°的轴向阵列组成,每排阵列有14个等间距的传声器。阵列安装在可周向旋转的测量段上,实验中测量段每隔6°旋转一次,共获得840个测点位置的声场信号。结果表明入射波与反射波最大可相差10dB。模态分解结果表明,转静干涉模态是转子通过频率及其谐频处的主导模态。利用不同参考信号计算出的声场结果相同,说明该实验测试方法对参考信号位置没有特殊要求,进一步说明该方法有很好的适用性。 相似文献
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A fixed frequency LCL-type series resonant converter (SRC) which uses an inductive output filter is proposed. Steady-state analysis of the converter is presented using complex ac circuit analysis. Based on the analysis, a simple design procedure is given. Detailed space integrated control experiment (SPICE) simulation results are presented to evaluate the performance of the designed converter under varying load and supply voltage conditions. Also, detailed experimental results obtained from a metal-oxide-semiconductor field-effect transistor (MOSFET) based 500 W converter are presented to verify the analysis and SPICE simulation results. The results obtained from the analysis, SPICE simulation and the experimental converter are compared. The proposed converter requires a narrow variation in pulsewidth while maintaining lagging power factor mode of operation for a very wide variation in the load as well as supply voltage 相似文献
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为了计算超音速轴对称头部进气道的流场,采用有限差分法编制了一个通用计算程序。该程序适用于皮托式、单锥、双锥、三锥、等熵锥等各种进气道的正问题气动设计。由于在进气道无粘流场计算中,采用了分离奇性的差分方法及混合使用显、隐差分格式,所以在边界点和内点及奇点邻域,计算结果均达到二级精度。程序可瑜出所需要的进气道各内流特性及外流特性。 文中列生了五个计算实例,并与特征线法计算结果和实验结果作了比较。符合程度令人满意。 相似文献
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A. V. Kochergin I. V. Ivshin A. R. Sabirov V. A. Gavrilov 《Russian Aeronautics (Iz VUZ)》2007,50(3):330-332
The results of experimental studies with the aid of the forced vibration method to determine the technical condition of GTE turbine blades are presented; the phase difference of two vibrations was used as a diagnostic indicator. The schemes of a diagnostic complex are given, the experiment procedure and results obtained are described. 相似文献
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徐爱杰%刘鸽平%李程刚%柯黎明 《宇航材料工艺》2006,36(Z1):93-95
针对2219铝合金搅拌摩擦焊的沟槽缺陷,用搅拌摩擦焊方法进行了补焊工艺研究,并对补焊焊缝的组织及性能进行了分析.结果表明,可以用搅拌摩擦焊的方法修复沟槽缺陷,二次补焊后的接头性能与单道焊时的接头性能相比没有变化,焊接变形小,且操作简单、方便. 相似文献
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Stanley C. Freden 《Space Science Reviews》1969,9(2):198-242
A survey of the present state of knowledge about the inner radiation zone is presented. This includes a historical review of empirical data and theoretical considerations concerning electrons, protons, and heavier particles. Included are results obtained from the various high-altitude nuclear tests. Recent experimental results are presented and some newer theoretical ideas, such as pitch-angle scattering and radial diffusion, are discussed as applied to the data. Comparisons of the measured fluxes, spectra, and time variations with the theoretical calculations are made where possible.Some conclusions are drawn pertaining to the sources and loss processes for the trapped particles, and some comments are made regarding future measurements in the inner zone. 相似文献