城市绿地的喷灌设计简介

简述城市绿地的喷灌技术及其设计计算,包括喷灌系统的组成及其造型、灌水量及管道的水力计算、管径和水泵的确定和选择等。设计合理的喷灌系统在满足需水要求的同时,可以满足景观和环境效果。     

稳态闪急沸腾喷雾速度分布的试验研究

为探索闪急沸腾喷雾的形成机理，以氟里昂R12为试验液体，采用激光多普勒测速仪(LDA)测量了稳定流动条件下粒子的速度分布。为作比较，还在相同试验条件下测量了传统压力雾化喷雾——柴油喷雾。试验结果表明：闪急沸腾喷雾的径向速度和径向扩散范围远大于传统喷雾，前者速度的空间分布远比后者均匀。闪急沸腾改善雾化的原因在于气相对液体射流的闪急冲击作用。     

石南大桥旧桥加宽与改造

随着交通量的日益增多，位于佛山境内的石南大桥旧桥宽度已不能满足交通需要，但检测其结构，健康状况良好，为此需对旧桥进行加宽改造。文中针对旧桥的具体情况进行了加宽与改造，并对施工中的注意事项进行了阐述。     

Determining the hydrodynamic forces on a planing hull in steady motion

A combination of methods was developed that can determine hydrodynamic forces on a planing hull in steady motion. Firstly, a potential-based boundary-element method was used to calculate the hydrodynamic pressure, induced resistance and lift. Then the frictional resistance component was determined by the viscous boundary layer theory. Finally, a particular empirical technique was applied, to determine the region of upwash geometry and determine spray resistance. Case studies involving four models of Series 62 planing craft were run. These showed that the suggested method is efficient and capable, with results that are in good agreement with experimental measurements over a wide range of volumetric Froude numbers.     

金属陶瓷镀膜技术在车用内燃机上的应用研究

为降低内燃机活塞环与气缸套表面的摩擦因数,提高发动机的机械效率,进而提高内燃机的性能,在内燃机活塞环上应用了金属陶瓷镀膜技术。在剖析了金属镀膜技术的理论基础和技术背景的基础上,着重介绍了在内燃机活塞环上应用金属陶瓷镀膜技术前后所进行的发动机对比试验研究。试验结果表明,采用此项技术后,发动机成本仅增加3%～5%,而整机动力性和经济性得到了明显改善,实用价值很高。     

武汉市中环线西环段8+725～9+030段软基处理

武汉市中环线西环段途径沟渠纵横 ,湖塘发育的地区 ,其土壤含水量大、孔隙率高。如何处理好软土地基是设计中的一个关键问题。本文结合在 8+72 5～ 9+0 3 0段软基采用粉喷桩处理的工程实践 ,对处理情况作了分析 ,并就粉喷桩设计、施工、补强和检测中的有关问题进行探讨。     

乙醇汽油喷雾特性研究及低压直喷喷嘴优化

通过闪光灯喷雾测试试验和乙醇汽油物性的测量、计算,对乙醇汽油喷雾特性进行了研究,最后使用AVL Fire软件完成低压喷嘴结构参数修改,并对不同喷嘴的雾化效果进行了对比.试验结果表明;混合燃料中乙醇比例增大导致乙醇汽油密度、黏度增大,乙醇比例与表面张力关系不大;喷雾贯穿距随着乙醇汽油密度和黏度的升高而降低,而喷雾角与表面...     

Experimental research on spray and combustion characteristics of the third generation conical spray

A new generation conical spray system for conventional diesel engines or premixed combustion diesel engines is introduced. By means of oriented impingement method, flexible spray penetration in design is realized. High-speed photograph was used to investigate the spatial distribution characteristics of the new spray for cases of different impingement angles and needle valve opening pressures. The results show that, by applying spray impingement orientation, fuel jets spread along the cone surface as shape of sectors, so the dispersion of jets is increased obviously. Changing on impingement angle leads to variation of penetration, which is critical in homogeneous mixture preparation. Due to the flexibility of spray penetration in design, the spray impingement on liner is avoided in a great extent. The results also indicate that higher needle valve opening pressure results in longer penetration and larger spray angle after impingement. Combustion characteristics of the impinged conical spray were studied in the 1135 type diesel engine. The new impinged conical spray system work smoothly in full load range with better fuel economy and lower emissions of NOx and soot than the original test engine.     

柴油机喷嘴空穴流动特性分析

利用混合多相流空穴模型进行了喷嘴内气液两相流动的数值模拟。分析了喷油压力、背压、喷嘴几何特征参数对喷孔内空穴流动、空穴区域分布的影响,以及各种参数对流量系数和燃油出口平均速度的影响。研究结果表明,无量纲空穴数直接影响喷孔内的空穴分布,而流量系数和燃油出口平均速度等流动特性则与喷油压力、喷孔入口圆角半径、喷孔倾角、针阀升程等几何特征参数有很大关系。     

缸内喷雾燃烧CFD仿真模型校验

摘要：采用AVLFIRE软件,对某重型柴油发动机进行缸内喷雾燃烧过程仿真。利用内窥镜系统,获得缸内喷雾燃烧图像。通过CFD仿真结果与喷雾过程、燃烧火焰、碳烟浓度分布进行定性对比分析,校验了缸内喷雾燃烧CFD仿真模型的准确性。