水煤浆喷嘴传热的有限元分析

采用有限元法分别对Al2O3/TiC陶瓷、YG8硬质合金材料的水煤浆喷嘴工作时的温度场和热应力进行了计算,分析了出口锥角对温度场和应力场的影响。结果表明:水煤浆喷嘴的出口端面温度最高,出口处热应力最大;温度和热应力沿轴向由出口到入口递减;相同结构的Al2O3/TiC陶瓷喷嘴的温度和热应力都大于YG8硬质合金,带出口锥角的喷嘴最高温度和热应力明显低于出口不带锥角的喷嘴。     

PVTt法气体流量标准装置参数的选择与确定

本文基于PVTt法气体流量标准装置的流量基本方程及装置的基本特征,详细分析与论证了装置主要参数,如标准容器容积V、充气初态Pi与终态压力Pf、质量流量qm或体积流量qv的选择与确定,特别对于该装置在整体上为非定常流中要保持流经流量计为定常流的基本特征、措施与气动设计方法作了全面、系统而深入的分析,涉及确定充气终态压力Pf的流动阻力系数的概念是首次由作者明确地引入的。     

铁路运煤车防冻液自动喷洒系统研究与应用

研制了铁路运煤车防冻液自动喷洒系统,在太原选煤厂进行了工业应用,喷洒机构和扁平扇形喷嘴向车厢内表面和煤中均匀喷洒防冻液,解决了冬季运煤时冻车问题。系统根据气温变化自动调节防冻液喷洒量,车头和车厢连接空档经过喷洒区时停止喷洒,降低了防冻液喷洒成本,减少了操作人员。     

Raising the Reliability, Efficiency, and Ecological Safety of Operation of the BKZ-210-140F Boiler Transferred to Stage Firing of Kuznetsk Coal in a U-Shape Flame

The BKZ-210-140F boiler of the West-Siberian Cogeneration Plant was equipped initially with four uniflow tangentially oriented burners and tertiary air nozzles. In order to raise the efficiency of operation and lower harmful emissions the boiler was reconstructed. U-shape aerodynamics was organized in the furnace by mounting 8 burners, 8 secondary air nozzles, and 8 tertiary air nozzles on the front and rear walls of the furnace. The reconstruction ensured higher stability of ignition of pulverized coal without flame division and rated temperatures of the superheater metal, lowered the optimum excess air factor at the outlet from the superheater to 1.2 – 1.25, decreased the concentration of nitrogen oxides in the combustion products to 360 – 380 mg/m³, and increased the gross efficiency of the boiler to 91.5 – 91.7%.     

Formation of drops at narrow slots in a centrifugal liquid–liquid contactor

In experiments on the dispersion of organic phases into aqueous phases, drops were generated continuously at narrow slots of width 12 μm ≤ w ≤ 125 μm mounted peripherally and normal to the radius in a ‘Hi‐Gee’ centrifugal contactor. The drops formed at an array of sources attributed to the Rayleigh‐Taylor instability distributed an average distance apart where σ is the interfacial tension of the phases, Δρ their density difference and g the applied centrifugal acceleration. Measured Sauter mean drop diameters were in the range 0.48 to 1.00 mm. The average drop size, d, was given by where d?* = 0.1538 ± 0.0016 m^1/3 is a measured capillary factor. Drop size was marginally affected by inertial forces at the highest flow rates.     

基于多喷头并联的3D打印机控制系统的研究

针对现有的单喷头3D打印机在打印大体积模型或零件时打印时间长、打印精度低等问题,提出了一种基于多喷头并联的3D打印机控制系统的设计方法,实现在模型切片平面的多轨迹并联打印。设计了光固化树脂并联打印喷头;采用主从式系统结构,以双STM32F407ZGT为核心、双PCL6045BL和CPLD（complex programable logic device,复杂可编程逻辑器件）为控制终端,搭建了一套双CPU （central processing unit,中央处理单元）的嵌入式3D打印机硬件控制系统;基于喷头切向跟踪原理和等间距打印原则,推导了二轴-四轴插补数据转换算法,实现了“二轴”轨迹数据到“四轴”插补加工数据的转换;设计了并联打印数据预处理程序、并联打印控制程序和并联打印脉冲输出控制程序以实现多轨迹并联打印控制;进行了控制系统的实验测试,对比了多喷头并联与单喷头3D打印机的实际打印效果。结果表明：与传统的单喷头打印方式相比,采用多喷头并联打印方式可以显著提高打印效率和打印精度,且打印质量较好。研究结果为大体积打印件的快速加工成型提供了一种切实可行的解决方案,具有一定的实用价值。     

Measurements of concentration decays in underexpanded jets through rectangular slot nozzles

Previously studies of hydrogen releases have focused on hydrogen jets through round nozzles, but leaks are more likely to result in jets through slots. In this study, the concentration decays along the jet centerline were measured for underexpanded jets from rectangular slot nozzles with aspect ratios (AR) of 1–12.6 for storage pressures up to 3.7 MPa. The mass fractions along the jet centerlines decay inversely with distance from the nozzle as with axisymmetric jets but with a faster decay rate. All the data collapses onto a single curve when normalized by the proper factor of the downstream location, except for the jets from square nozzles (AR1). The decay rates for jets from rectangular nozzles with AR greater than unity are significantly larger than for the jets from square nozzles. The jets from square nozzles behave somewhat like the circular jets from circular nozzles due to the symmetric geometry, so the decay rate is closer to that of circular jets relative to the jets from the other rectangular nozzles. This database will be useful for model validations for the modeling of jets from rectangular nozzles.