Effects of cavity-induced mixing enhancement under oblique shock wave interference: Numerical study

In this research, the effects of oblique shock on the mixing characteristics in a supersonic combustor equipped with a cavity is numerically investigated. To reveal the flow structure of the supersonic flow field under oblique shock wave interference, three-dimensional steady RANS equations and SST k-ω turbulence model are adopted. The current work focuses on comparing the interaction effects between oblique shock wave and bow shock wave, which are formed by fuel jet on fuel mixing under different conditions. The numerical analysis demonstrates that an optimal angle exists for the mixing efficiency of the ramp. The optimal angle diminishes as the jet-to-crossflow pressure ratio increases. The oblique shock wave in a certain range is conducive to enhance the penetration depth of ethylene. The smaller angle of the ramp does not cause large stagnation pressure losses.     

论住宅区坡地景观设计现状及其发展趋势

目前,我国的住宅区坡地设计有三种倾向:统一和融合、多功能性、现代技术和现代材料的使用,并存在形式化和盲目性问题.住宅区坡地设计的发展趋势表现在整体性、人性化、创新和可持续发展方面.     

立交桥匝道沉陷原因分析与治理

通过对哈尔滨二环南直路立交桥匝道 4填方工程产生的沉陷进行补充勘察 ,分析了沉陷产生的原因 ,提出了软弱新近堆积土补强方法 ,介绍了其治理效果     

立交匝道平面线形优化设计及MATLAB的应用

本文在探讨最优化计算理论与方法的基础上,分析立交匝道平面线形设计的特点与方法,拟定线形组合型式,建立平面线形优化设计的数学模型,给出相应的优化计算方法,并应用大型通用的辅助计算软件MATLAB优化工具箱里的优化函数,实现线形参数的优化设计。     

基于Ramp响应技术的雷达目标3D图像重构

在雷达目标识别的应用中,目标形状的3D图像可提供识别目标的最直接和最有用的信息。Ramp响应技术是一种应用最为广泛的低频雷达目标成像技术,而最终的目标图像质量主要取决于图像重构算法的性能。因此,在详细介绍了两种典型的基于Ramp响应技术的3D图像重构算法的基础上,对两种算法在不同条件下进行了仿真比较,提出了一种计算重构图像轮廓函数的算法,并利用该算法计算图像与目标之间的误差,分析比较了两种算法的性能,得出了有益的结论。     

三山岛金矿新立分矿斜坡道通风系统优化

以三山岛金矿新立分矿斜坡道通风系统为研究对象,针对其存在的斜坡道能见度低、炮烟矿尘积聚、湿度大以及各个中段联巷风流紊乱等问题,运用通风网络优化技术以及风机优选技术展开了系统研究,提出采用强制通风方式将矿山主竖井、措施井的新鲜风流从-240 m中段东北巷引入斜坡道的通风模式,并采用Ventsim三维通风动态仿真模拟软件进行了解算。结果表明：通过优化井下东、西两翼回风路线,在67#线运输巷增设1台K45-6-№16型风机后,斜坡道进风量由15.03 m3/s提高至50.12m3/s,-320,-360,-400,-440,-480 m中段斜坡道联巷的进风量分别为11.33,11.21,11.15,11.09,11.01 m3/s,理顺了斜坡道通风系统,斜联巷风流紊乱现象得到有效改善,为矿山安全生产提供了技术支撑。     

Precipitation kinetic of Al3(Sc,Zr) dispersoids in aluminium

The non-isothermal formation of Sc- and Zr-containing dispersoids in Al–Zr–Sc ternary alloys has been investigated by atom probe tomography (APT). In the early stages of precipitation, a high number density of Sc-rich clusters form. These clusters subsequently transform into Al₃Sc particles with a L1₂ structure. When Zr diffusion becomes significant, Zr atoms are found to segregate to Al₃Sc/α-Al matrix interfaces. Further annealing at 748 K gives rise to a duplex core/shell structure.     

Numerical analysis of welding residual stress using heat source models for the multi-pass weldment

Numerical prediction of welding-induced residual stresses using the finite element method has been a common practice in the development or refinement of welded product designs. Various researchers have studied several thermal models associated with the welding process. Among these thermal models, ramp heat input and double-ellipsoid moving source have been investigated. These heat-source models predict the temperature fields and history with or without accuracy. However, these models can predict the thermal characteristics of the welding process that influence the formation of the inherent plastic strains, which ultimately determines the final state of residual stresses in the weldment. The magnitude and distribution of residual stresses are compared. Although the two models predict similar magnitude of the longitudinal stress, the double-ellipsoid moving source model predicts wider tensile stress zones than the other one. And, both the ramp heating and moving source models predict the stress results in reasonable agreement with the experimental data.     

接水盒注塑成型工艺分析及模具设计

介绍了冰箱接水盒注塑件的成型工艺特点及注塑模具的结构特点及工作过程。通过采用斜导柱,弹簧等为动力实现了侧孔,卡钩等注塑件上的侧成型特征。该注塑模具设计成为需要侧成型开关的注塑模具典范。     

MasterDrive变频器使用外加斜坡给定的研究与应用

西门子MasterDrive变频器内部带有一个复杂功能的斜坡发生器,用于将阶跃给定增加斜坡后发给速度调节器。在某些场合比如设备需要复杂起动特性的时候,变频器需要接收外加的带斜坡的速度给定,这就需要对其进行特殊的设置。本文对外加含斜坡速度给定信号进行了分析,并提出了处理方法,最后举例说明了该方法的实际应用情况。