双稳射流元件压力特性的研究

用理论分析和数值模拟和实验研究的方法，分析了双稳射流元件内流体流动的状况，计算了压力在双稳内的传播和压力波射流的控制。计算结果显示，射流由双稳元件内的压力控制，且压力呈现周期性变化。控制压力会随入口压力的变化而不同。     

下喷自吸环流反应器内气-液-固三相流局部非线性特性(英文)

应用重标度范围（Ｒ／Ｓ）分析技术和吸引子重构技术,初步研究了下喷自吸环流反应器内气－液－固三相流动的时序压力波动的局部分形维数和局部最大Ｌｙａｐｕｎｏｖ指数特性．结果表明,在喷射有效区和导流筒内管流区,分形维数和最大Ｌｙａｐｕｎｏｖ指数均随喷射液体流量和固体颗粒加入量的增加而增大,且局部分形维数与最大Ｌｙａｐｕｎｏｖ指数的分布规律相似．在本文实验条件下,反应器内最大Ｌｙａｐｕｎｏｖ指数均为正值,表明该反应器内的流动行为呈现混沌特性．局部分形维数和局部最大Ｌｙａｐｕｎｏｖ指数等局部非线性表征参数可用来从更深层上揭示三相环流反应器内的流动特性,例如流区过渡及流动结构等．     

主流区风口模型在室内气流CFD模拟中的应用

分析了4类风口模型（即基本模型、盒子模型、N点动量模型、主流区风口模型）在计算流体动力学中的应用以及在实际工程案例中的运行情况.在环境舱内进行了足尺实验,利用全方位热风速表测量了环境舱内的气流速度和温度场,并与4类风口模型的模拟结果进行比较.结果表明：基本模型与盒子模型并不适用于结构复杂的送风口模拟;基于N点动量模型和主流区风口模型的流体速度在工作区的模拟值与实测值的相对误差小于20%;在主流区风口模型中,送风口附近的气体速度模拟值与实测值的最大相对误差小于15%.证明主流区风口模型相对于其他3类风口模型而言,对于结构复杂的送风口模拟更准确,应用性更强.     

Reaction thrust of water jet for conical nozzles

Clear knowledge on the reaction thrust of water jet is valuable for better design of water jet propulsion system. In
this paper, theoretical, numerical and experimental studies were carried out to investigate the effects of the nozzle geometry
as well as the inlet conditions on the reaction thrust of water jet. Comparison analyses reveal that the reaction thrust has a
direct proportional relationship with the product of the inlet pressure, the square of flow rate and two-thirds power exponent
of the input power. The results also indicate that the diameter of the cylinder column for the conical nozzle has great influence
on the reaction thrust characteristics. In addition, the best values of the half cone angle and the cylinder column length exist
to make the reaction thrust reach its maximum under the same inlet conditions．     

Reaction thrust characteristics of high-pressure submerged water jet of cylinder nozzles

The shapes and geometrical parameters of nozzles are key factors for fluidics. The relationship among the reaction thrust, flow rate pressure, diameter do and length L of a cylinder nozzle is analyzed theoretically. The simulation of the flow field characteristics was conducted via the FLUENT computational fluid dynamics package. Effects of the inlet conditions and the nozzle dimensions on the reaction thrust of a water jet were addressed particularly. The reaction thrust experiments were performed on a custom-designed test apparatus. The experimental results reveal that a） the nozzle diameter and the inlet conditions exert great influence on the water jet reaction thrust; and b） for L≤4d0, where the nozzle is treated as a thin plate-orifice, the reaction thrust is independent of nozzle length; for L〉4d0, where the nozzle is treated as a long orifice, the reaction thrust can reach maximum under the condition of a certain flow rate. These findings lay a theoretical foundation for the design of nozzles and have significant value, especially for the future development of high-oressure water-let orooulsion technology.     

一种塑编行业实用的喷水平织机纬线折边装置

综述了国内塑编行业的现状,分析了国内纺织行业织机折边装置的应用,介绍了塑编业喷水平织机纬线折边装置的结构与原理,总结了喷水平织机纬线折边装置的技术特点.     

低压蒸喷制冷技术的应用与实践

为了保证高效低耗和环境无污染,本钢热连轧厂采用了低压蒸喷制冷技术,该技术以蒸汽和水为介质,不采用任何化学制冷剂和载冷剂,用蒸汽做动力,通过能量转换实现制冷。实践表明采用低压蒸喷制冷技术节能10%,并且可以100%回收蒸汽冷凝水。     

择时运动在时差调整中的作用初步研究（一）

】通过对大白鼠进行择时运动，观察其中枢神经系统的端脑中的神经递质去甲肾上腺素（ＮＥ）、多巴胺（ＤＡ）、５－羟色胺（５－ＨＴ）在模拟飞行中的节律峰相位移度，以探讨择时运动在时差调整中的作用。结果表明，择时运动对中枢神经递质的节律峰相位有明显的导引作用。中枢抑制性神经递质ＤＡ表现出“过度滞后现象”。实验为教练员应用择时运动调整运动员的生理机能和克服时差综合症提供了理论依据     

Effects of cryogenic cold air jet cutting on chip break in metal machining

1.IntroductionTherequirementsforenvironmentalprotectionaregettingstricterworldwide.Notonlythenaturalecologyandresourcesshouldbeconsideredinconservation,butalsotheenvironmentbeprotectedfrombeingsacrificedastheexpenseofproductivityboosts.Aconventionalmachiningprocessusedtotakeoilasthelubricantandcoolantforthesurfacesofmachinedtoolsandworkpieces,whichbroughtforthenvironmentpollution,andincreasedcostsonpost-treatingoftools,workpiecesandcuttingscrap.Asaresult,greenmachiningtechnologyfeaturingcleanp…     

华北南部一次暴雪过程的诊断分析

利用风廓线资料、探空资料、NCEP1o×1o逐6小时再分析资料和常规观测资料,对2011年11月29~30日影响华北南部的一次低槽冷锋类暴雪天气过程进行了诊断分析,结果表明：(1)东北风急流为干冷性质,850hPa以下冷空气强迫抬升、地形抬升是暴雪的主要触发机制;(2)850hPa-700hPa逆温层的出现和850hPa以下偏东风的增强对降雪的发生、发展有很好的指示意义;在垂直结构上出现了自下而上的湿-干-湿的比湿层结结构;(3)唐山风廓线仪测风计算的温度平流变化及监测到东北风急流的出现对于华北南部暴雪有重要联系,冷平流大值中心的出现对暴雪区发生时段有很好的对应关系。