复合材料加筋板后屈曲承载能力工程分析方法

根据复合材料的力学特性,结合有限元理论和工程经验,提出了一种计算复合材料加筋板结构后屈曲承载能力的工程简化理论与方法,并以复合材料J型加筋板计算模型为例,从工程角度说明了计算后屈曲承载能力的思路与公式.利用该方法通过算例计算,将计算结果与实验结果进行对比,发现该种复合材料加筋板稳定性计算方法可以解决后屈曲的几何非线性带来的计算难度,能保持较高的精度,并可用于飞机结构设计的实际应用中.     

基于弱耦合的翼伞气动变形数值模拟

对不带气室翼伞和带气室翼伞的气动特性和结构变形进行三维数值模拟,分析气室对翼伞气动特性和结构变形的影响.流场方面,采用有限体积法求解Navier-Stokes控制方程,选用剪切应力输运(SST,Shear-Stress Transport)k-ω湍流模型;结构方面,假定翼伞有初始形状,使用插值方法映射传递流固交界面的压力数据,通过ANSYS计算翼伞伞衣的气动变形.结果表明:气室对阻力影响不大,对升力的影响主要表现在大迎角情况下;翼伞柔性和尺寸大小对其有利迎角的范围影响不大;翼伞的气动变形和最大主应力主要集中在气室中前部分,带气室翼伞由于有肋片加强的缘故,伞衣气动变形较小,一定程度上保证了翼伞的气动特性.     

纳米CuO/AP复合粒子的制备及催化性能研究

采用溶剂-非溶剂法制备出了以纳米CuO为核、AP为壳的CuO／AP复合粒子。TEM、KRD及从的测试结果表明。复合粒子中只有CuO和AP存在,且AP包覆于CuO的外表,而DSC对复合粒子催化性能的测试结果表明。纳米CuO／AP复合粒子中AP的高温分解峰温度下降到101℃,较CuO-AP的简单混合物提前了5．64℃,而且复合粒子中AP的低温分解峰消失,在完成由斜方晶系向立方晶系的晶型转变后,便直接进入了高温分解,这为改善推进剂燃速提供了一条可行途径。     

喷口遮挡对射流式姿控火箭发动机性能的影响

通过数值模拟和试验研究,分析了喷口遮挡对姿控火箭发动机性能的影响。结果表明,当发动机喷口被遮挡时,姿控发动机不能跟随控制指令产生所需的反向推力,其稳定弹轴的能力减弱,从而影响火箭弹的落点精度。     

固体火箭发动机喷管及羽流流场的数值分析

采用FLUENT流动计算软件对某空射型导弹发动机的喷管及羽流流场进行了一体化的数值仿真研究,分析了导弹飞行高度和马赫数对喷管羽流流动的影响。仿真结果与地面热试车观察到的结果相吻合,可为固体火箭发动机的研究开发提供参考。     

尿素法制备氮化物陶瓷材料的研究进展

综述了近年来尿素法制备氮化物陶瓷粉体、涂层、纳米管和陶瓷基复合材料等的研究进展,并对其发展趋势作了展望.     

Lunar exosphere influence on lunar-based near-ultraviolet astronomical observations

The potential effect of the lunar exosphere on the near-ultraviolet sky background emission is predicted for Lunar-based Ultraviolet Telescope (LUT: a funded Chinese scientific payload for the Chang’e-III mission). Using the upper limit on the OH concentration inferred from the recent MIP CHACE results, our calculations show that the sky brightness due to the illuminated exosphere is <8.7 photons⁻¹ cm⁻² arcsec⁻² within the wavelength range 245–340 nm. By evaluating the signal-to-noise ratios of observations of an AB = 13 mag point source at a series of sky background levels, our analysis indicates that the detection performance of LUT can be moderately degraded by the lunar exosphere emission in most cases. An AB = 13 mag point source can still be detected by the telescope at a signal-to-noise ratio more than 8 when the OH concentration is less than 2 × 10⁸ molecules cm⁻³. However, the effect on the performance is considerable when the exosphere is as dense as suggested by CHACE.     

Physical Body Impact After High Altitude Bail-out

In most of the emergency circumstances,the aircrew leaves the aircraft under unsatisfied conditions,such as too high relative velocity to the ambient air or low partial oxygen pressure.The aircrew must pass through this area as quickly as possible before opening the parachute safely,viz.,free-fall.Numerical simulations are conducted in this paper to explore the major characteris-tics of the aircrew free-fall process by using a commercial computational fluid dynamic(CFD) software,FLUENT.Coupled with the classical pressure-altitude and temperature-altitude relations,Navier-Stokes(N-S) equations for compressible flow are solved by using finite volume method.The body velocity and the attitude are predicted with six-degree of freedom(6DOF) module.The evolution of velocities,including horizontal,vertical components and angular velocity,is obtained.It is also analyzed further according to the particle kinetic theories.It is validated that the theories can predict the process qualitatively well with a modi-fied drag effect,which mainly stems from the velocity pressure.An empirical modification factor is proposed according to the fitting results.