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591.
The flow-field of a propane-air diffusion flame combustor with interior and exterior conjugate heat transfers was numerically studied.Results obtained from four combustion models,combined with the re-normalization group(RNG) k-ε turbulence model,discrete ordinates radiation model and enhanced wall treatment are presented and discussed.The results are compared with a comprehensive database obtained from a series of experimental measurements.The flow patterns and the recirculation zone length in the combustion chamber are accurately predicted,and the mean axial velocities are in fairly good agreement with the experimental data,particularly at downstream sections for all four combustion models.The mean temperature profiles are captured fairly well by the eddy dissipation(EDS),probability density function(PDF),and laminar flamelet combustion models.However,the EDS-finite-rate combustion model fails to provide an acceptable temperature field.In general,the flamelet model illustrates little superiority over the PDF model,and to some extent the PDF model shows better performance than the EDS model. 相似文献
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充有弹性介质多层复合材料圆筒壳稳定性 总被引:1,自引:1,他引:0
本文分析了充有弹性介质的多层复合材料圆筒壳在轴压、侧压与水压作用下的稳定性。所采用的方法是用Galerkin—差分法求介改型的Donnell方程,再根据稳定准则确定临界值。若干算例已在文中列出。计算结果表明:内部介质材料性能和壳体的边界条件对临界载荷有较大影响。本文采用的分析方法和结论可供固体火箭发动机壳体设计工作者参考。 相似文献
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本文提出一种预测拦截末制导方法。用等价预测碰撞线代替预测碰撞线,只需要探测视线的角速度,使需要探测的参数减少。文中还提出了外扰动常驻条件下,渐近稳定系统的设计方法。应用该方法设计出的末制导系统,可使导弹的攻击区扩大到一个蛋形球空间,使原理脱靶量趋于零。为说明以上结论,给出了仿真结果。 相似文献
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Evaluation of active hybrid fuel cell/battery power sources 总被引:1,自引:0,他引:1
Lijun Gao Zhenhua Jiang Dougal R.A. 《IEEE transactions on aerospace and electronic systems》2005,41(1):346-355
Hybrid fuel cell/battery power sources have potentially widespread uses in applications wherein the power demand is impulsive rather than constant. Interposing a dc/dc converter between a fuel cell and a battery can create two configurations of actively controlled hybrid fuel cell/battery power sources. Those two configurations are compared using both theory and experiment with special attention to the peak power enhancement, and power losses in the converter. Both of the defined configurations were built, using a 35 W polymer electrolyte membrane (PEM) fuel cell, an 8-cell lithium-ion battery pack, and a high-efficiency power converter. Both two configurations yielded a peak power output of 135 W, about 4 times as high as the fuel cell alone could supply, with only a slight (13%) increase of weight. The converter losses were quantitatively analyzed. Which of the two configurations yields a smaller loss depends on the load power demand characteristics including peak power and load duty ratio. The study results provide guidance for the design of hybrid sources according to the particular load power requirements. 相似文献
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本文介绍了北方航空公司机场客运CBT教学系统的总体结构,特点及其各部分功能,并介绍了系统的实现及性能维护。 相似文献
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Nanzhi Jiang Jian Li 《IEEE transactions on aerospace and electronic systems》2001,37(4):1254-1266
This study considers the clutter suppression and feature extraction of multiple moving targets for airborne high range resolution (HRR) phased array radar. To avoid the range migration problems that occur in the HRR radar data, we divide each HRR profile into nonoverlapping low range resolution segments. No information is lost due to the division and hence no loss of resolution occurs. We show how to use a vector auto-regressive filtering technique to suppress the clutter. Then a relaxation-based parameter estimation algorithm is presented for multiple moving target feature extraction. Numerical results are given to demonstrate the effectiveness of the algorithm 相似文献