送风速度对碰撞射流气流特征影响的实验研究

通过实验研究了碰撞射流冬季热风供热时不同的送风速度对室内温度场和热舒适性的影响情况。对不同送风速度的影响效果进行分析,结果表明碰撞射流冬季热风供暖时送风速度对室内温度场、速度场和热舒适性有显著影响。     

定风量系统下碰撞射流通风的供热效果分析

对碰撞射流通风在定风量系统下的供热特性进行了数值模拟,并且对不同送风口安装高度和送风温差下的室内温度场分布和热气流扩散距离进行了分析。结果表明:同一送风温差时,送风口高度越高,热气流扩散距离越短;同一送风口高度时,送风温差越小,热气流扩散距离越长,由温度分层引起的不舒适感就会减弱。     

风机盘管机组测试用风量测量装置的设计

风量测量装置是空气焓差法测试系统中的重要部件,主要包括：围护结构、温湿度取样装置、喷嘴等部件,本文阐述了以上部件的设计思路,并结合实例,分析了各部件的技术难点及解决方案,研究结果对该装置的推广具有重要的指导意义。     

压差式流量开关在冰蓄冷空调中的应用研究

针对目前冰蓄冷空调机组（带制冰工况）的水流检测中出现的种种故障,提出了在冰蓄冷空调系统中使用压差式水流开关检测水流量的应用.     

脉冲电晕等离子体技术脱除有害气体研究进展

概述了脉冲电晕等离子体技术脱除有害气体的研究现状,总结了影响等离子体技术脱除有害气体效率的主要因素及可能的脱除机理,讨论了用等离子体处理有害气体的研究方向及应用前景。     

微磨料浆体射流形成过程的能量传输

为了研究微磨料浆体射流形成的能量传输与转换,用碳化硅磨料对40CrMnMo7钢进行冲击,建立数学模型描述冲击力与射流压力、喷嘴效率、射流流量、水力功率等参数的相互影响,通过测量射冲击力、射流流量来预测射流系统的单位水力功率的出力状况。结果表明,该数学模型可以预测射流冲击力与水力功率之比,由系统压力模型计算的冲击力比实验结果小20%;在射流的滞止区内,压力与冲击力不呈线性关系,在相同压力下,磨料粒子具有更大的动能,微磨料浆体射流冲击力比纯水射流的大20%,单位水力功率提供的射流冲击力随着射流压力的增大而减小;射流冲击力随着喷嘴直径、射流压力的增大而增大,在靶距较小的情况下,冲击力随着靶距的增大而增大,当靶距达到一定值时,冲击力随着靶距的增大而减小。     

On the Method of Air Jet Cooling in Green Manufacturing

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喷雾半干法脱硫塔内射流卷吸特性的数值模拟

喷雾半干法烟气脱硫塔内射流卷吸特性对塔内烟气与吸收剂的混合以及流场分布均匀有着重要影响。该文通过数值模拟的方法,分析双流体雾化喷嘴的射流卷吸混合特性,得到喷雾半干法烟气脱硫塔内射流流场分布。结果表明：双流体雾化喷嘴在塔内流场呈现中间大两边小的对称分布,并且在靠近塔壁的两侧产生了回流;射流流体与周围气体发生动量交换,对周围气体有明显的卷吸作用,沿着射流轴线方向,射流卷吸量逐渐增加,随着伴随风量的增加,射流卷吸量也逐渐增加。     

等离子体喷枪中的射流脉动控制

电弧等离子体喷枪中的射流脉动是影响等离子体喷涂质量的一个非常重要的因素,射流脉动很大程度上是由于等离子体喷枪内电弧分流引起的.分析了电弧分流的机理及其对射流脉动的影响.在此基础上,设计了一种直流等离子体喷枪,采用在阳极和阴极中间设置隔离段的方法来限制电弧的大尺度分流.为了研究电弧分流对射流脉动的影响以及检验新喷枪对射流脉动的抑制作用,而建立了专门的试验装置并进行了相关的试验.试验结果表明,电弧分流和射流脉动的频谱特性是一致的,在使用新等离子体喷枪时,电弧分流明显得到了限制.     

Characteristic Analyses of Plasma Air Cleaning Systems for the Removal of Indoor Air Pollutants

Tobacco smoke is one of the most common manmade aerosols. Yellow sand dust and pollen are the particular and regional pollutants generated by natural phenomena. These pollutants have different removal characteristics, respectively, when the air cleaning system is operated. It is well known that tobacco smoke particles are removed effectively with electrostatic precipitators. But it is necessary to evaluate whether the plasma air cleaning system has good performance of removing Yellow sand dusts and pollens simultaneously and also to establish the operation modes for efficient removal of those particular air pollutants by controlling the air flow rates passing the electrostatic precipitator and operating times of air cleaning system. In this study, the performance evaluation of plasma air cleaning systems is investigated with tobacco smoke particles, Yellow sand dusts, and pollens. For the multi-pass test in occupied spaces of 150 m³, the operation time required to reduce dust concentration from the initial concentration of 300 µg/m³ to 150 µg/m³, the criteria of indoor air quality in Korea, are 40 min for tobacco smoke, 28 min for Yellow sand dust, and 5 min for pollen when the flow rate is 17 m³/min. Also, the optimal operation modes for each pollutant are suggested for the efficient removal of indoor air pollutants. At first, most particles are removed by maximum flow operation. Second, the rest of the particles are removed by medium flow operation. Next, the plasma air cleaning systems are maintained by minimum flow for tobacco smoke mode and by repeating minimum flow and medium flow for Yellow sand and pollen modes. Edit to “Because the Yellow sand dust and the pollen flow into the room continuously and settle down … noise reduction.” Because the Yellow sand dust and the pollen flow into the room continuously and settle down. The plasma air cleaning system is suitable for the removal of the tobacco smoke, the Yellow sand dust, and the pollen for maintaining suitable indoor air quality, and, if it is operated through the suitable operation mode, energy efficiency will improve noise reduction.     

动力气垫地效翼船的流体空气动力性能研究

文章简要阐述了动力气垫地效翼船的空气--流体动力设计特点和难点,及"天鹅"号地效翼船的试验研究。由于采取一系列措施,使艇在静垫升性、两栖性、耐波性与气动力配平和运动稳定性等方面,在船模与实船上均取得令人满意的结果。     

锂电池涂布烘箱风嘴射流压强分布优化研究

目的烘箱射流风嘴对极片烘干的均匀性和一致性具有重要影响,拟改善干燥过程中由于射流压强分布不均导致的极片烘干质量不良问题。方法利用SolidWorks软件对射流风嘴与极片间的空气流体域进行建模,基于k-ε湍流方程完成热风流场的数值仿真计算,根据流体仿真结果对射流风嘴结构进行优化设计,最后通过实验对数值仿真计算结果进行验证与完善。结果经数值仿真优化后的极片与风嘴间压强分布较改进前有较大提升,在相同的测量位置处,仿真得到的压强差由20 Pa下降到了8 Pa,实验得到的压强差由21 Pa下降到11 Pa,在误差允许范围内,实验结果与仿真结果基本保持一致。结论优化后的射流风嘴完善了射流压强分布,数值仿真研究对风嘴结构的优化设计具有重要的指导意义。     

采用环状流实现均匀分配的空调器分流器研究

为解决空调器中多流路换热器内制冷剂分配不均的问题,本文设计了一种能够均匀分配两相制冷剂的新型分流器样件并进行了可视化实验。设计均匀分流器的基本思路是构建环状流并均匀分配环状流,具体设计方法是提出分流器进口管结构的计算方法实现环状流的构建,并通过设计新型进、出口管的连接结构实现环状流的均匀分配。实验表明：制冷剂的质量流量为14~22 g/s时,水平、倾斜和竖直安装的新型分流器的质量流量不均匀度比传统圆锥式分流器分别下降10%~24%、14%~27%和24%~47%。基于环状流整流的新型分流器的分配性能优于目前最常用的圆锥式分流器。     

热膜式空气质量流量传感器动态非线性建模

热膜式空气质量流量传感器响应速度较快,测量范围宽,可靠性高,广泛应用于发动机空燃比的测量。但是,这种传感器的动态非线性问题影响了进气量测量的精度。采用基于多幅值阶跃信号的Hammerstein模型和两步辨识方法描述了传感器的特性。通过动态标定实验,得到不同幅值的阶跃输入、输出数据。根据幅值,用最小二乘拟合方法确定非线性系数,由输入数据和非线性系数得到静态非线性环节的输出。根据输出数据,运用线性自回归方法得到动态线性环节的传递函数。这样就建立起块联形式的动态非线性模型,有利于传感器动态非线性的校正。建模结果表明,动态非线性模型比线性模型可更准确地描述传感器的特性。     

气流紧实机理及影响因素的研究

在自行研制的气流紧实试验机上,对气流紧实过程进行了研究,特别是采用了加速度传感器,考察了型砂在气流作用下的运动过程、同时就各种工艺参数和结构参数进行了研究,最后在大量实验的基础上建立了描述型砂惯性冲击力的数学物理模型、并与实验结果进行了比较。     

喉嘴段收缩半角对液气射流泵流场特性影响的数值研究

基于计算流体动力学,对不同的液气射流泵喉嘴腔收缩半角进行了三维数值计算,根据数值计算结果,分析了喉嘴腔收缩半角对液气射流泵内部流场情况的影响,以及对液气射流泵吸气效率的影响关系。研究结果表明:随着喉管收缩半角的增大,流量比先略有升高然后略微减小随后保持不变,压力比先急剧增大,达到峰值后缓慢减小,存在最大值;射流泵的效率随收缩半角的变化趋势与压力比的变化趋势相似,存在最大值。根据最大吸气效率减小5%来确定最优吸气效率区间,相应的喉管收缩半角的最优范围为13.5°~17.1°。     

涡轮分级机分级轮流场的数值模拟与分析

为进一步研究涡轮分级机流场中的分级轮径向速度和分级区流场分布情况,更好地指导涡轮气流分级机的设计、优化和运行,通过用FLUENT6.2中的分离-隐式求解器对涡轮分级机的流场进行了模拟与分析。主要针对分级机径向速度的均匀性分析,并与实验进行比较。结果表明:进入分级轮的气流径向速度不均匀,分级轮的高度越高,径向速度越不均匀,较高的分级轮会有部分气流外溢,外溢位置、大小与分级轮的高度相关,从而引起进入分级轮的径向气流速度反而增大,高径比最好为0.3～0.5。     

循环风量对新型家用半导体纯净水机系统性能的影响

针对目前家用净水机需要频繁清洗和更换滤芯的问题,本文提出并搭建了一种利用半导体珀尔贴效应和空气增湿去湿原理相结合的家用净水系统,实验研究了循环风量对系统运行工况、功耗、单位时间产水量和单位能耗产水量的影响。实验结果表明：随着循环风量的增加,半导体冷热端温度逐渐下降,冷热端温差略有下降,系统制冷量、半导体功耗和制冷性能系数(COP)逐渐上升。当循环风量为100 m3/h,单位时间产水量和单位能耗产水量达到峰值,分别为345 g/h、459 g/(kW?h)。系统所制取水的卫生指标(TDS＜3 mg/L)符合国家饮用水标准,系统日产水量(＞7.2 L/d)满足一般家庭饮水需求。     

Modeling Performance of a Tangential Flow Cyclone: Effects of Secondary Outlet Geometry and Boundary Conditions

Numerical calculation of the performance of cyclones for gas-particle separation is becoming a popular tool for cyclone analysis and design. A traditionally accepted way to treat these problems is by solving the flow field and particle transport equations in the spatial domain (C1) limited by the inlet and overflow outlet cross-sections, where the flow is usually assumed fully developed, and the dust outlet cross-section. Formulation of the boundary conditions for the flow and particles’ transport at the dust outlet cross-section remains an open question. We address this problem numerically by comparing results of calculations performed by the above traditional approach, i.e., treating the problem in configuration C1, as well as in extended domains, namely those including a dust collecting bin (configuration C2) and a downcomer tubular outlet (configuration C3). Two boundary conditions at the downflow outlet were checked for each configuration, namely, a blocked outlet (zero velocity) and an open outlet (zero gas flow rate). Toward this goal, an efficient computational fluid dynamic (CFD) model of turbulent flow based on the Reynolds Stress turbulent closure scheme was developed, validated, and used to calculate velocity field and the pressure drop as well as particle cut size and separation efficiency in several Stairmand-type tangential flow cyclones. The results were tested and corroborated against the experimental data reported in the literature, including careful measurements performed by Gottschalk and Bohnet (1995 Gottschalk , O. , and M. Bohnet . 1995 . Two stage circuit for the separation of fine particles. PARTEC 95, Europ. Symposium on Separation of Particles from Gases, Nurnberg, March.  [Google Scholar], 1998 Gottschalk , O. , and M. Bohnet . 1998 . Calculation of grade efficiency and pressure drop of aerocyclones with suction of partial gas stream. PARTEC 98, European Symposium Separation of Particles from Gases, Nurnberg, March.  [Google Scholar]) for a 225 mm tangential flow cyclone, with downflow outlet connected to a tubular extension.

Particle separation in the traditional C1 cyclone configuration was shown to be most sensitive with respect to the choice of the boundary conditions at the downflow outlet, whereas with the dust outlet connected to a bin (C3 configuration) this condition has a much weaker effect on the fractional efficiency. Solutions for the C1 and C2 configurations, both combined with the blocked downflow outlet boundary condition yielded the cyclone's pressure drop in agreement with the Gottschalk and Bohnet's data. However, C2 configuration which contained a downcomer tubular extension was found preferable for correlating the measured fractional efficiency.     

新型超音速压气机内气固两相流场CFD模拟分析

为预测和预防压气机叶轮磨损，基于多相流理论对超音速压气机内的三维气固两相流场进行数值模拟。在分析中将压气机内的流场按可压缩气体处理，同时考虑温度对颗粒运动轨迹的影响。模拟结果表明，叶片出口端部前缘，温度达到最大，颗粒的运动速度也达到最大值。由此判明叶轮磨损最严重处位于叶片端部。