EXPERIMENTAL INVESTIGATIONS ON DIFFUSION CHARACTERISTICS OF HIGH CONCENTRATION JET FLOW IN NEAR REGION

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｒｅｓｅａｒｃｈｏｆｊｅｔｉｓａｎｉｍｐｏｒｔａｎｔｆｉｅｌｄｉｎｆｌｕｉｄｍｅｃｈａｎｉｃｓ.Ｉｔａｌｓｏｈａｓｍａｎｙａｐｐｌｉｃａｔｉｏｎｓｉｎｅｎｇｉｎｅｅｒｉｎｇ ,ｆｏｒｅｘａｍｐｌｅ ,ｔｈｅｄｉｓｃｈａｒｇｅｏｆｐｏｌｌｕｔａｎｔａｎｄｃｏｏｌｉｎｇｗａｔｅｒｉｎｉｎｄｕｓｔｒｉｅｓ .Ｗｈｅｎｔｈｅｉｎｉｔｉａｌｄｅｎｓｉｔｙｏｆｔｈｅｊｅｔｉｓｄｉｆｆｅｒｅｎｔｆｒｏｍｔｈａｔｏｆｔｈｅａｍｂｉｅｎｔｗａｔｅｒｂｏｄｙ ,ｔｈｅｊｅｔｗｉｌｌｂｅａｆ…     

用大涡模拟方法计算尾水管内非定常周期性湍流

本文运用大涡模拟-双方程模型进行尾水管内部非定常周期性湍流计算。而且本文对尾水管复杂计算域的网格划分，提出一种更加合理的多块结构网格。计算结果用波形显示了尾水涡带和压力脉动的主要性质和运动特征。     

Measurements of turbulent mass transport of a circular wall jet

The results of a laboratory investigation on the turbulence characteristics of a circular three-dimensional turbulent wall jet are presented. Measurements were taken up to 50 nozzle diameters using combined particle image velocimetry and planar laser induced fluorescence. The results showed that the induced turbulence was still evolving in the present range and had not achieved similarity. While the turbulent intensity for both velocity and concentration increased downstream, the turbulent mass transport showed a decline over distance for both the streamwise and spanwise directions, implying weakening dispersion from the jet core.     

横流均匀环境中三维线源型正负浮力射流特性研究

本文利用混合有限分析法及交错网格。对横流均匀环境中三维线源型正负浮力射流及负浮力射流的特性进行研究，分析了不同工况下流速，温度和湍动能在断面上的分布及影响射流轨迹线的因素，讨论了轨迹线上温度的变化及浮力射流的贴壁现象。对三维长线源型负浮力射流，分析了流速比，喷口弗汝德数对负浮力射流的影响。     

热流体喷射变形机理与喷嘴结构

高速短程纺技术能生产三维卷曲短纤维,该技术的关键之一是热流体喷射装置。本文介绍了热流体喷射装置的演变与特点及它的加工机理和某些已应用的实际装置。     

柔性管自激振动减阻效果的实验研究

在实验确认柔性管紊流减阻效果的基础上,采用双重管结构,对柔性管的自激振动减阻效果进行了实验研究。结果表明:管的壁厚越小自激振动的减阻率越大;在雷诺数约为2.2×104时,壁厚为2 mm,3 mm及4 mm的柔性管自激振动减阻率依次约为13%,10%,8%。     

无捻毛巾产品毛羽问题的分析与实践

对无捻毛巾产品毛羽问题进行了分析,对成因进行了初步探索.通过试验,制定了较为有效的改进措施和工艺.无捻毛巾制品的毛羽问题得到改善,并控制在一个较为合理的范围内.     

影响喷气燃料与橡胶相容性的因素

采用几种具有不同初始物理性能及不同丙烯腈含量、不同硫化剂和硫化程度的丁腈橡胶，考察了其配方和物理性能对采用不同工艺条件生产的喷气燃料的相容性。结果表明，喷气燃料与橡胶的相容性不仅与喷气燃料的加工工艺有关，而且与橡胶的组成及其制备工艺有关。采用非加氢工艺生产的喷气燃料与橡胶的相容性好于采用加氢工艺(特别是加氢裂化工艺)生产的喷气燃料。橡胶材料的初始力学性能的好坏并不完全决定其与喷气燃料相容性的好坏，橡胶材料的耐过氧化物侵蚀能力才是影响相容性好坏的主要因素。橡胶的组成和其制备工艺决定了橡胶在喷气燃料中萃取物的数量和组成，不同萃取物的综合作用给相容性带来不同程度的影响。用硫作硫化剂的橡胶虽然原始强度低于用过氧化物作硫化剂的橡胶，但前者与喷气燃料的相容性却远好于后者。     

可控环量船用翼的数值模拟和试验研究

本文提出一种可控环量船用翼数值模拟方法,其计算结果与最近Mclachlan的试验数据十分吻合。通过本文的计算,对广泛引用的Kind ＆ Maull的二维试验数据提出了修正。根据本文所作的三维可控环量帆翼的试验结果,与二维计算值的比较,指出它们之间所存在的显著差别。     

Pulsating Jet Impingement Heat Transfer Enhancement

This article presents results from a numerical study of pulsating jet impingement heat transfer. The motivation is to seek conditions offering a significant enhancement compared to steady flow impingement drying. The CFD software package FLUENT was used for simulating slot-type pulsating jet impingement flows with confinement. The parameter study included velocity amplitude ratio, mean jet velocity, and pulsation frequency. The distance from nozzle exit to surface was three times the hydraulic diameter of the nozzle. The Reynolds number based on the nozzle hydraulic diameter and jet temperature was 2,460 with a mean jet velocity of 30 m/s, which is the base case of the numerical experiments. Results showed that time-averaged surface heat transfer increased with increasing velocity amplitude for the same mean jet velocity. Large velocity amplitudes helped enhance heat transfer by two mechanisms: high jet velocity during the positive cycle and strong recirculating flows during the negative cycle. For the cases with different mean jet velocities but the same maximum velocity, time-averaged surface heat flux decreased with decreasing mean jet velocity. As for the effects of pulsation frequency, with high-velocity amplitude ratio, time-averaged surface heat fluxes were at the same level regardless of frequency. However, at low-velocity amplitude ratio, high frequency caused stronger recirculating flows resulting in greater heat transfer compared to the cases with a lower frequency.