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511.
无纵向温度变形的复合材料管的铺层设计 总被引:2,自引:0,他引:2
提出了无纵向温度变形的复合材料管子铺层设计的一种方法。通过对三类碳纤维/环氧复合材料的管子的实例计算表明:高模碳纤维,而不是极高模量碳纤维,更适合于航天结构的应用。 相似文献
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为了提高瞬态响应的计算速度和精度,构造了基于快速傅立叶变换的响应计算格式,并研究了这种格式的本质。理论分析和数值仿真表明:a所提的计算格式能够提高速度8 倍;b基于抛物线型求积公式的算法精度最高;c只要频域采样点数 M 超过时域采样点数2 倍,计算精度就与 M无关。 相似文献
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采用有限体积法直接求解时域麦克斯韦方程组,研究了二维圆柱、翼型和三维球体、立方体、双球体等典型完全导电目标的电磁散射问题。空间离散使用近似黎曼解构建网格通量,并针对二维结构网格、三维自适应直角切割网格分别给出重构方法,时间方向采用二步龙格库塔法。计算与理论、实验或文献结果符合良好。 相似文献
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The effectiveness of grinding fluid supply has a crucial impact on grinding quality and efficiency in high speed grinding. In order to improve the cooling and lubrication, through in-depth research of self-inhaling internal cooling method and intermittent grinding mechanism, a new spray cooling method used in high speed grinding is proposed. By referring to the structure of bowl- shaped dispersion disk, the grinding wheel matrix with atomization ability is designed; through studying heat transfer of droplet collision and the influence of micro-groove on the boiling heat transfer, grinding segment with micro-groove is designed to enhance the heat flux of coolant and achieve maximum heat transfer between droplets and grinding contact zone. High-speed grinding experiments on GH4169 with the developed grinding wheel are carried out. The results show that with the micro-groove grinding wheel just 5.4% of pump outlet flow rate and 0.5% of spindle energy is needed to reduce the grinding temperature to 200℃, which means the developed grinding wheel makes cooling high efficient and low energy consuming. 相似文献
518.
‘‘Tian Tuo 1'(TT-1) nano-satellite is the first single-board nano-satellite that was successfully launched in China. The main objective of TT-1 is technology demonstration and scientific measurements. The satellite carries out the significant exploration of single-board architecture feasibility validation, and it is tailored to the low-cost philosophy by adopting numerous commercialoff-the-shelf(COTS) components. The satellite is featured with three-axis stabilization control capability. A pitch bias momentum wheel and three magnetic coils are adopted as control actuators.The sun sensors, magnetometers and a three-axis gyro are employed as the measurement sensors.The quaternion estimator(QUEST) and unscented Kalman filter(UKF) method are adopted for the nano-satellite attitude determination. On-orbit data received by ground station is conducted to analysis the performance of attitude determination and control system(ADCS). The results show that the design of ADCS for TT-1 is suitable, robust and feasible. 相似文献
519.
A seal device as an important component of aeroengines has decisive influence on per- formance, reliability, and working life of aeroengines. With the development of aeroengines, demands on the performance characteristics of seal devices are made strictly. Finger seal as a novel kind of sealing device, recently attracts more and more attentions in academic circles and engineer- ing fields at home and abroad. Research on finger seals has been extensively developed, especially on leakage and wear performances under dynamic conditions. However, it is a pity that the work on finger seals has been limited with a single approach that is improving the performance by structural optimization; in addition, the technology of dynamic analysis on finger seals is weak. Aiming at the problems mentioned above, a distributed mass equivalent dynamic model of finger seals considering the coupling effect of overlaid laminates is established in the present paper, the dynamic perfor- mance of 2.5 dimension C/C composite finger seal is analyzed with the model, and then the effects of fiber bundle density and fiber bundle preparation direction on finger seal's dynamic performance are discussed, as well as compared with those of Co-based alloy finger seal. The current work is about dynamic analysis of finger seals and application of C/C composite in this paper may have much academic significance and many engineering values for improving research level of finger seal dynamics and exploring feasibility of C/C composite being used for finger seals. 相似文献
520.
发展了一种基于目标函数误差估算的网格自适应准则,进而通过网格自适应处理提高目标函数计算的效率和准确性。首先描述了目标函数的误差估算及修正的方法,该方法通过伴随方程将原方程的残值误差与目标函数联系起来。然后,基于误差估算建立网格自适应准则,以减少目标函数修正后的剩余误差,提高目标函数计算结果的准确性,并将方法进一步发展至多目标问题。最后将该准则应用于Euler方程控制的NACA0012翼型无粘可压流动的网格自适应模拟。数值计算成功地捕获了与升力、阻力和力矩等目标函数相关的特征流动区域,计算出符合指定精度要求的目标函数值,验证了本文所发展的方法。 相似文献