高层建筑外表面对流换热系数的数值模拟研究

通过西安市1幢既有高层住宅建立几何模型,以西安地区的自然气候条件为基础,运用CFD软件模拟外墙外表面的对流换热系数情况。研究结果表明风速对高层建筑对流换热系数影响很大,并成正比例关系;建筑高度对对流换热系数也有一定影响,主要表现在迎风面上成正比,背风面上无明显影响;风向投射角也会影响高层建筑表面的对流换热系数,在迎风面上随着夹角的变大对流换热系数也变大,对背风面无太大影响。     

薄规格带材气垫式连续热处理新技术研究

利用开发的新型带材气垫式加热-淬火装置,实验研究了新型气垫式射流喷嘴喷射压力、风速、风温及带材张力等参数对漂浮高度、漂浮稳定性和换热均匀性的影响规律,借助有限元模拟及数学建模等方法开发出动态漂浮技术和层级串联淬火技术,解决了传统气垫式热处理炉、淬火装备漂浮稳定性可控性不强,换热效率不高,换热均匀性差等难题.研究表明,采用新型装置和技术实现漂浮托举力增加近1倍,换热均匀性提高近1倍,淬火后带材平直度≤25I.     

The Hybrid Drop Test

To verify the cushion performance of transport packaging, two traditional drop test methods – free fall and controlled shock tests – and a traditional simulation method are often used. However, it is difficult to assure the safety of a test product when the traditional drop test method is applied, and results from the traditional simulation method are not sufficiently accurate to be used to test packaging material. Therefore, we propose a new test method called ‘the hybrid drop test’ by integrating the traditional drop test and simulation methods. The hybrid drop test ensures the safety of the test product and improves test efficiency. The results of the verification test show that this new drop test method can be applied to test the cushion performance of pulp mould transport packaging. Copyright © 2013 John Wiley & Sons, Ltd.     

Effects of ambient pressure and precursors on soot formation in spray flames

The effects of ambient pressure on soot formation in spray jet flames are investigated by means of a two-dimensional direct numerical simulation (DNS). In addition, the effects of precursors on soot formation are also discussed. The inception models considering acetylene and polycyclic aromatic hydrocarbon (PAH) precursors are employed and compared in this study. The extended flamelet/progress-variable approach (EFPV) in which heat transfer between a droplet and the surrounding fluid can be considered is employed as a combustion model. Jet A is used as a liquid fuel with considering the detailed chemistry including 274 chemical species and 1537 elemental reactions by the flamelet library. The evaporating droplets’ motions are tracked by the Lagrangian method and the non-equilibrium Langmuir–Knudsen model is used as an evaporation model. Results show that the spray jet flame structure and the soot formation characteristics are considerably affected by the ambient pressure condition. The soot volume fraction increases with increasing the ambient pressure. It is also revealed that the dominant process to promote the soot formation is different between the acetylene and PAH precursor models. It is essential to model a soot inception process with appropriate precursors in order to understand a detail mechanism of soot formation, since the precursor which plays the important role depends on the type of fuel and the combustion conditions.     

聚能射流前驱波起爆靶板屏蔽炸药的数值模拟

为系统地研究聚能射流前驱波对靶板屏蔽炸药冲击起爆的影响,从前驱波的形成机理出发,结合前驱波在靶板中传递时能量的衰减、作用面积的增大和在靶板-炸药界面能量的转化,对炸药冲击起爆的窄脉冲准则进行改进,构建了聚能射流前驱波冲击起爆靶板屏蔽炸药的数学模型,并对模型进行了详细地分析和研究,得到如下结论:对于直径3mm的聚能射流,其前驱波最大可起爆约4.2mm钢板屏蔽的A4炸药,符合试验结论;前驱波起爆能力的降低主要是由于作用面积的增大和不同材料交界面的能量转化,说明可以通过靶板厚度与靶板层数之间的最优组合,以最小的代价达到最大的前驱波防护能力,为复合靶板的研究、野战弹药生存能力的提高和废旧弹药的处理提供了理论依据.     

高程拟合取代水准测量研究

本文主要研究的是GPS高程拟合方面的内容,重点介绍了二次曲面高程拟合模型。。结合对内蒙某矿高程数据水准拟合结果说明利用GPS定位技术,不但可以获取地面点的精密平面坐标,而且,通过建立一定范围内的GPS高程异常模型也可以较精密的拟合地面正常高。其成果很可靠。理论分析和实践检验表明,在平坦地区的局部GPS控制网测量中,GPS高程测量可以逐步代替四等水准测量是可行的。     

船用喷射制冷机组的研究及发展现状

船用喷射制冷机组可以有效利用船舶上低品位热能,实现能源的节约和高效利用。简述了喷射制冷的原理,进行了热力学分析,对船用蒸汽喷射制冷机组及余热回收式喷射制冷机组的研究及发展现状进行了分析,并对太阳能等新型喷射制冷机组船用化进行了展望。     

鞍钢2150ASP线花纹板工艺开发与生产实践

介绍了鞍钢2150ASP生产线花纹板的开发及生产情况。选定了花纹的尺寸,制定了合适的轧制工艺,保证了花纹高度符合标准要求,将基板厚度×系数作为来料厚度进行卷取机的辊缝设定,实现了卷取机各辊缝值的全自动设定。通过工艺改进,单根花纹辊轧制量达到了1.5~2.0万t,解决了花纹板生产过程中卷取机上夹送辊表面挂腊缺陷,提高了生产效率,降低了生产成本。     

含能油墨配方设计及其在微孔装药中的应用

为优化微装药方法及设计合适的含能油墨配方,将喷墨打印装药和湿法压装两种装药方法结合起来,发现装药密度得到明显提高,装药均一性较好。采用激光点火方式,结合高速摄影和X射线衍射(XRD)等对微孔燃烧过程及其燃烧产物进行分析,获得了含能油墨中载体种类、纳米Al/Cu O含量和Φ值对微孔燃烧的影响规律。发现硝化棉(NC)不但有很好的油墨性能、装药性能,而且点火燃烧性能良好。得到以下结论:载体为NC且质量分数为7.5%,Al/Cu O的Φ值为1.6,初步测得最优配方下平均冲量约为145μN·s。