有限元仿真模拟在超声喷水无损检测用水套设计中的应用

水套在超声喷水穿透检测中具有重要作用,为设计出具有良好耦合效果的水套,减少水流紊流对声波耦合的影响,本文通过构建探头套几何模型、物理建模、数值求解的有限元仿真方法对探头水套进行流体动力学仿真。结果表明,在无整流装置下,从入水口射入的水流撞击探头套内壁,产生严重紊流,进入出水管后,紊流状态仍然保持,水流流线方向杂乱。增加整流装置后,探头套内紊流得到很好的抑制,使得进入出水管的水流流线方向趋向一致,这种现象随着整流片增多而效果越加明显。本文为后续模拟水流经过出水口后的水柱状态,特别是随着初始水流速度加大后的水柱状态,以及利用有限元多物理场模拟功能,在加入声场后,模拟紊流状况下声场的变化打下了基础。     

磁絮凝在餐饮废水中的应用研究

以COD去除率作性能参数,考察了几种复合磁絮凝剂在高、低二种浓度餐饮废水中的絮凝效果。研究结果表明:与普通絮凝剂相比,采用复合磁絮凝剂处理餐饮废水不仅能大大缩短分离时间、减少污泥体积,还能提高絮凝效果。     

复合工作液提高高速走丝电火花线切割效率研究

从极间放电特性的角度,分析了目前阻碍高速走丝电火花线切割(WEDM-HS)工艺指标提高的原因.指出WEDM-HS在使用含油比例较少的复合工作液作工作介质后,会因为极间冷却状态的改善而获得切割工艺指标的大幅度提高,一次稳定切割的效率已经超过200 mm2/min.     

Estimation of vertically integrated water vapor in Hungary using MODIS imagery

Information about the amount and spatial structure of atmospheric water vapor is essential in understanding meteorology and the Earth environment. Space-borne remote sensing offers a relatively inexpensive method to estimate atmospheric water vapor in the form of integrated water vapor (IWV). The research activity reported in the present paper is based on the data acquired by the HRPT/MODIS (High Resolution Picture Transmission, MODerate resolution Imaging Spectroradiometer) receiving station established in Budapest (Hungary) by the Space Research Group of the Eötvös Loránd University. Integrated water vapor is estimated by the remotely sensed data of the MODIS instrument with different methods and also by the operational numerical weather prediction model of the European Centre for Medium-Range Weather Forecasts (ECMWF). Radiosonde data are used to evaluate the accuracy of the different IWV fields though it has been pointed out that the in situ data also suffers from uncertainties. It was found that both the MODIS and the ECMWF based fields are of good accuracy. The satellite data represent finer scale spatial structures while the ECMWF data have a relatively poor spatial resolution. The high quality IWV fields have proved to be useful for radiative transfer studies such as the atmospheric correction of other satellite data from times different than the overpass times of satellites Terra/Aqua and the forecast times of the model data. For this purpose the temporal variability of IWV is scrutinized both using ECMWF and MODIS data. Taking advantage of Terra and Aqua overpasses, the mean rate of change of IWV estimated by the near infrared method was found to be 0.47 ± 0.45 kg m⁻² h⁻¹, while it was 0.13 ± 0.65 kg m⁻² h⁻¹ based on the infrared method. The numerical weather prediction model’s analysis data estimated −0.01 ± 0.13 kg m⁻² h⁻¹ for the mean growth rate, while using forecast data it was 0.24 ± 0.18 kg m⁻² h⁻¹. MODIS data should be used when available for the estimation of the IWV in other studies. If no satellite data are available, or available data are only from one overpass, ECMWF based IWV can be used. In this case the analysis fields (or the satellite field) should be used for temporal extrapolation but the rate of change should be calculated from the forecast data due to its higher temporal resolution.     

水滴撞击特性的动态图像测量方法

用石膏脱模的方法制作圆柱实验件.实验采集圆柱试件表面不同位置染色过程的动态视频数据;依据圆柱驻点处色度值时序信号的增长曲线,将实验划分为欠饱和区、平衡区和过饱和区3个阶段;将平衡区RGB色度空间的色度值c与水滴撞击特性的局部水收集系数建立关联.结果表明:平衡区的比色分布符合局部水收集系数相对驻点处β/β_m分布;不同位置c值增长曲线具有相似性,缩比时间尺度1/t_b分布符合数值仿真欧拉法β/β_m分布的定义;实验结果与数值仿真结果对比误差率小于10%.     

舰船油,水系统监控和动力系统技术诊断研究

本文简要论述了舰船油、水系统监控和动力系统技术诊断原理,介绍了以微处理机为核心的监控与技术诊断系统的关键硬件设计要点和软件主程序设计框图,A/D转换虑波程序、数据采集、故障处理及声光报警程序设计。给出了新研制的舰船油、水系统监控和系统技术诊断的背景性参考实例的调试经验。     

关于对黄河治理与开发的设想

黄河的危势无时无刻不在威胁着黄淮海平原人们生产与生活的安全,人们都在探讨对黄河的治理与开发的方案,有人建议废弃旧河床重修新河道,有人建议让它改道等等。但,不管采取什么样的治理方式,如果不能从根本上解决黄河的泥沙沉积问题,将都不能从根本上使黄河得到治理。设想从解决黄河泥沙沉积问题入手,探寻治理与开发黄河的途径。     

航空发动机地面模拟吞水试验

介绍了航空发动机地面模拟吞水试验的试验目的、试验设备、大气中的雨水状况；提出了军、民用发动机的吞水试验要求；分析了试验选用的雨滴直径；计算了试验用水量。     

几种特种纤维的热水老化及性能研究

在25℃,50℃和96℃的热水中,对Kevlar29纤维、Kevlar49纤维和PBO纤维分别进行了吸水老化实验,测定了吸水率和拉伸断裂强度与热水老化条件(即温度和时间)的关系,通过FTIR图谱分析了纤维在吸水过程中可能发生的化学结构变化,通过SEM观察了热水老化导致的纤维表面微观形貌变化,讨论了纤维的吸水机理。     

液氢突扩燃烧冲压发动机性能

对航天飞机用液氢突扩燃烧冲压发动机性能进行了比较详细的计算及分析。研究的工作范围为Ma=1.50～6.50、高度变化范围为H=0～40km。并把计算结果与等截面液氢冲压发动机性能进行了比较。计算结果表明,在低空低马赫数时突扩燃烧冲压发动机性能较为优越,而在高空高马赫数时性能基本没有变化。航天飞机使用突扩燃烧室冲压发动机在低空低马赫数时可以部分解决流量匹配问题,还可提高发动机推力、减少溢流阻力。燃烧室结构也较简单。