大面积无衬底自支撑金刚石厚膜沉积

讨论了在采用直流电弧等离子体喷射ＣＶＤ工艺沉积大面积无衬底自支撑金刚石厚膜时遇到的若干技术问题,在制备过程中经常出现的膜炸裂现象,主要是由于膜和衬底材料线膨胀系数差异引起的巨大热应力,而衬底表面状态的控制、沉积过程中工艺参数的优化和控制也是一个重要的因素,因此,必须对整个金刚石厚膜沉积过程进行严格而系统的控制,团能有效地保证获得无裂纹大面积金刚石自支撑厚膜。     

前混合磨料高压水射流切割喷嘴的数值模拟

为了延长喷嘴的使用寿命,提高水射流设备的使用效率,对前混合磨料高压水射流的喷嘴结构进行了优化设计.利用CFD软件对几种典型喷嘴的内部流动进行了数值模拟和仿真,得到了压力分布图、速度分布图、紊动能分布图及轴线上轴向速度图等仿真结果.对仿真结果进行了对比分析,得出了结构型式较好的喷嘴,为耐久喷嘴的研制提供了依据.分别用3种喷嘴做了一系列的试验,并与仿真结果进行了对比,证明仿真结果是准确的.     

Visualization of Coherent Structures in Acoustically Forced, Gas-Particle Turbulent Round Jet

To show the effects of the particles and forced disturbances on the instantaneous large-scale vortex structures in a gas-particle round jet, coherent structures in gas-particle turbulent round jets were investigated experimentally by flow visualization. The 45-μm and 350-μm diameter glass beads were used as the particles in the experiments. An acoustic speaker was used to introduce velocity perturbations at the jet exit. The Strouhal number based on the nozzle diameter, exit velocity, and forcing frequency was varied from 0,1 to 0.9. The Reynolds number was 9400. The coherent structures were visualized in unforced and forced single-phase jet flows and unforced and forced particle-laden jet flows with different diameter glass beads. The experimental results show that the particles have significant effects on the gas phase coherent structures. The coherent structures are controlled by the large 350-μm diameter particles, while the structures are mainly dominated by the forced disturbances in the flows with 45-μm diameter particles.     

A THEORY ON TEA-POT EFFECT

In this paper exit.bend angle(tea-pot effect)has been analysed theoretically based on thebasic)aw of hydromechanics.It was proved that it is the transverse shear stress that causes exitbend angle while the bending direction is along with the resultant force of the shear stresses andthe magnitude of the exit angle is directly proportional to the resultant force.The equation re·lating exit bend angle with the resultant force was set up and experiment verification of theequation was carried out with rational agreement to theoretical results.     

高压射流雾化性能实验分析

利用高压射流雾化系统，观测了不同条件对射流雾化形态的影响，并对射流雾化规律进行了分析。其结果参于再生式液体发射药火炮弹道性能稳定性控制具有指导意义。     

喷气纺纱条动态气圈的转速与成纱强力的关系

喷气纺纱是利用旋转气流作用推动纱条形成气圈运动,使头端自由纤维加捻成纱。本文采用本组研制的纱条气圈转速仪对喷气纺纱纱条动态气圈的转速进行了测试,并就改变加捻成纱过程中的第一喷嘴和第二喷嘴的气圈转速,探讨其与成纱强力的关系。     

比热变化对激波诱导气动矢量喷管影响的数值研究

采用基于雷诺平均的二维Navier-Stokes方程和RNG κ-ε 湍流模型的有限体积法,考虑比热随温度的变化,对激波诱导气动矢量喷管的流动情况和性能进行了数值仿真研究。结果表明:与平均定比热计算相比,变比热计算的喷管流动情况发生了较大变化,激波位置前移、激波强度减弱、喷管出口气流平均速度增大;进一步分析发现,与平均定比热计算相比,变比热计算的喷管推力系数、推力矢量角、推力矢量效率均有所增大。     

燃气射流对多联装导弹发射箱前盖影响

针对导弹发射离箱之后,喷管处的高温高速燃气可能吹破多联装发射箱相邻前盖的情况,在进行导弹头部下沉、整体下沉等滑离参数计算的基础上,利用计算流体力学方法分析在不同导弹姿态、离箱距离等条件下燃气流对发射箱前盖表面压力、温度的影响情况,仿真结果显示各个发射箱前盖参数分布有较大差异,仿真结论对工程实践中贮运发射箱的设计具有一定的参考作用.     

一种改进的开槽结构对叶栅性能影响的数值研究

基于利用小槽出口射流控制叶片吸力面分离气流的思想,为获得更好的叶栅流场特性,在两段式平行直线转折槽结构的基础上,提出一种改进的开槽结构,用CFD方法对2种结构开槽前后的叶栅流场进行数值模拟分析对比。为进一步研究改进结构的槽道出气角对叶栅性能的影响,另设计了多种出气角度。计算结果表明,改进的槽道能够更好地改善叶栅性能,获得更高的气流转折角和静压升,以及更低的总压损失。槽道出气角对叶栅性能也有较大的影响。