Research on static characteristic of double redundance double nozzle flapper valve based on AMESim

The feedback spring rod of the armature assembly is cancelled in the double redundance double nozzle flapper valve(DRDNFV),and the difficulty of valve core displacement control is increased.Therefore,this paper intends to study the static characteristic of DRDNFV through the AMESet and AMESim simulation.It is explored under the circumstance of the fixed orifices being clogged and experimentally verified on the test bench.The results show that the pressure gain increases and the flow gain decreases with the increasing clogged degree of the fixed orifices on both sides.The zero bias increases synchronously with the increasing clogged degree of the unilateral fixed orifice.The experimental results are basically consistent with the theoretical curves and the theoretical correctness of the simulation model is effectively verified.The results can provide the theoretical reference for design,debugging,maintenance and fault diagnosis of DRDNFV.

Middle or low water pressure direct spiral double helix converging nozzle structure optimization and flow field analysis

In order to solve the problem of using new nozzle is proposed in fire rescue robot. middle or low water pressure to form fine water mist, a Existing water mist nozzles are basically used for high pressure and in large size, complex structure and poor low pressure atomization effect in comparison with requirement of snake-like fire rescue robots. On the basis of comprehensive typical spray noz- zles, a direct spiral double helix converging nozzle （DSDHCN） is proposed, which has the advanta- ges of small volume, light weight, simple structure, and convenient installation. To make the spray nozzle have good performance, and meet the requirements of more efficient fire extinguishing, a nu- merical study is carried out to analyze the internal and external full flow field of nozzle. A gas-liquid two-phase flow is applied to simulate the external full flow field of nozzle with VOF model in fluent software. The simulation results show the real situation of water flow out of the atomization nozzle and the water jet trajectory. Some simulations about middle or low water pressure direct spiral double he- lix converging optimized nozzle have been done in 30bar pressure. The simulation results show that the optimized nozzle structure not only makes the spray droplets have a good cone angle, but also have a sufficient axial velocity,which proves the structure rationality of the proposed optimized nozzle.

Numerical Simulation and Experimental Study of Heat-fluid-solid Coupling of Double Flapper-nozzle Servo Valve

The double flapper-nozzle servo valve is widely used to launch and guide the equipment. Due to the large instantaneous flow rate of servo valve working under specific operating conditions, the temperature of servo valve would reach 120℃ and the valve core and valve sleeve deform in a short amount of time. So the control precision of servo valve significantly decreases and the clamping stagnation phenomenon of valve core appears. In order to solve the problem of degraded control accuracy and clamping stagnation of servo valve under large temperature difference circumstance, the numerical simulation of heat-fluid-solid coupling by using finite element method is done. The simulation result shows that zero position leakage of servo valve is basically impacted by oil temperature and change of fit clearance. The clamping stagnation is caused by warpage-deformation and fit clearance reduction of the valve core and valve sleeve. The distribution roles of the temperature and thermal-deformation of shell, valve core and valve sleeve and the pressure, velocity and temperature field of flow channel are also analyzed. Zero position leakage and electromagnet＇s current when valve core moves in full-stroke are tested using Electro-hydraulic Servo-valve Characteristic Test-bed of an aerospace sciences and technology corporation. The experimental results show that the change law of experimental current at different oil temperatures is roughly identical to simulation current. The current curve of the electromagnet is smooth when oil temperature is below 80℃, but the amplitude of current significantly increases and the hairy appears when oil temperature is above 80℃. The current becomes smooth again after the warped valve core and valve sleeve are reground. It indicates that clamping stagnation is caused by warpage-deformation and fit clearance reduction of valve core and valve sleeve. This paper simulates and tests the heat-fluid-solid coupling of double flapper-nozzle servo valve, and the obtained results provide the reference value for the design of double flapper-nozzle force feedback servo valve.

Optimization for aerodynamic performance of double serpentine nozzles with spanwise offsets using Taguchi-based CFD analysis

Serpentine nozzles are widely used in combat aircraft to realize strong stealth characteristics.Based on the layout characteristics within a confined space,a series of double serpentine nozzles with spanwise offsets are established.Using computational fluid dynamics and Taguchi method,the influence mechanisms of the Distribution of Area(DA),Distributions of Centerline for the first and second‘S’sections in the Vertical direction(DCV1 and DCV2),and Distribution of Centerline in the Spanwise direction(DCS)are analyzed.The impact of these factors on the total pressure recovery coefficient can be ranked as DA>DCV2>DCS>DCV1,whereas their impacts on the discharge coefficient and axial thrust coefficient can be ranked as DCV2>DCS>DA>DCV1.Considering the statistical significance of these factors,a nozzle in which DA changes rapidly at the exit and DCV1,DCV2,and DCS change rapidly at the entrance gives the best aerodynamic performance.Compared to the worst configuration,the total pressure recovery coefficient,discharge coefficient,and axial thrust coefficient are improved by 1.6%,3.5%and 3.6%,respectively.DA influences the gas flow acceleration in the entire serpentine channel,resulting in different wall shear stress and friction losses.The various centerline distributions influence the gas flow acceleration effects and form complex wave structures in the constantarea extension section,resulting in different local and friction losses.

一种喷口控制的多目标约束设计方法

为克服试凑法在控制回路参数优化中的局限性,针对涡扇发动机在加力状态易出现喷口摆动的不协调现象,考虑喷口双环控制结构工作特点,采用按需正向设计策略,按照控制系统时域、频域性能指标设计要求,制定兼顾频域、时域性能要求的内、外环协调控制的设计目标准则,提出一种喷口控制的多目标约束的差分进化内外环控制参数自整定优化设计方法,在双转子涡扇发动机非线性模型上进行闭环控制系统仿真验证。结果表明:在飞行高度从0增加到10 km、飞行马赫数从0加速到0.9的起飞和爬升状态进入加力过程以及平飞中保持飞行马赫数不变的关断加力过程中,发动机未出现喷口摆动等现象,涡轮落压比最大相对误差不大于1.5%,喷口闭环控制系统具有期望的伺服跟踪和抗飞行条件变化干扰能力。

双孔扇形喷头在选煤厂的应用

随着选煤厂入洗原煤压力增加,脱介筛筛上煤层变厚,选煤厂现有脱介筛喷头脱介能力不足,产品携带介质量增多。为进一步降低介质消耗量,设计了一种双孔扇形喷头,在选煤厂进行了应用研究,取得了良好效果,为降低重介分选过程介耗提供了技术支撑。结果表明:使用双孔扇形喷头时,<1 mm粒级的产率为0.58%,筛上细泥含量降低约1.7个百分点。<0.045 mm和0.038 mm粒级的磁性物产率占比分别为94.93%和91.41%,稀介质中<0.5 mm和0.25 mm粒级的非磁性物产率占比分别为52.02%和34.53%,磁性物与非磁性物含量提高1.5个百分点,较广角扇形喷头脱介性能更佳。筛下稀介质浓度提升1.5个百分点,可在一定程度上减缓稀介系统的处理压力。

双孔扇形喷头脱介性能试验及分析

为解决选煤厂传统脱介筛喷头透筛难、脱介效率低的问题,拟设计一种双孔扇形喷头,通过搭建脱介试验系统,在实验室开展了脱介性能的试验研究。结果表明:大喷管直径、切槽角度、偏移量的喷头结构有利于降低筛上磁性物含量,与传统喷头相比,喷头脱介与脱泥效率提升。确定了双孔扇形喷头的关键结构参数为喷管直径φ10 mm,切槽角度70°,偏移量3 mm,喷管倾斜角度分别为35°和40°。

钢包双水口及滑板设计优化

针对转炉钢包机构上水口子母台周围易产生裂纹、上滑板易产生横断、下水口与长水口配合不佳等问题,优化上水口子母口的结构,增加子母台的有效果使用面积,提高上水口与上滑板配合安全系数,在与长水口配合角度不变的情况下,延长配合深度,将装配下水口调整为内装式,从设计上改进了滑板耐材安全系数,减轻了职工劳动强度,缩短了修包时间。

双喷嘴挡板刹车控制阀参数敏感度研究

基于某型民用客机刹车系统架构,介绍了国内某型民用飞机刹车系统所配套的刹车控制阀的结构及工作原理,通过AMESim软件建立基于结构化的模型,仿真分析关键参数,如负载容积、弹簧预紧力、滑阀遮盖量、喷嘴前置级阻尼孔孔径、喷嘴孔径、回油路阻尼孔孔径、喷嘴挡板间隙、弹簧管弹性模量、弹簧管壁厚及磁间隙等对刹车控制阀输出特性的敏感度,辅助产品正向设计,指导产品装配调试,帮助定位产品故障原因,提高产品的性能稳定性及可靠性。

环卫车旋转喷杆喷嘴射流技术分析

深度保洁车是近年来市场较受欢迎的一种道路保洁环卫车,其核心部件是旋转喷杆喷嘴。文章对深度保洁车的旋转喷杆喷嘴进行分析,相比传统洗扫车的直线喷杆喷嘴,旋转喷杆喷嘴能够有效消除梳子印,有着更好的清洗效果。不足之处是作业车速较慢,因为旋转喷杆转速与车速存在对应关系,当转速低于车速对应的临界值地面就会出现螺旋线,影响清洗效果。同时对比主动旋转与自旋转的清洗效果,以及对旋转双喷杆喷嘴和旋转三喷杆喷嘴的运动分析,为设计深度保洁车旋转喷杆喷嘴提供更好的指导意见。

挖沟机双喷嘴冲击射流的数值研究

海底射流式挖沟机或疏浚设备的使用过程中涉及到双喷嘴冲击射流问题,揭示射流流场的演化规律有望对工程问题提供理论支持。使用CFD方法对二维双喷嘴淹没条件下射流冲击固体壁面问题进行建模并求解,分析在不同射流靶距、喷嘴间距以及射流流速下流速场、冲击区压力及剪应力的分布特性。验证算例表明,CFD方法可以获得较好的预测结果。计算结果表明,喷嘴间距越小,冲击区压力分布越大;射流靶距减小时,射流压力骤增,且在双喷嘴之间会形成振荡效应,让冲击区压力及剪应力大小和位置发生波动。在实际工程中,应注意这种振荡效应对机械运动稳定性的影响。

双长水口七流中间包结构优化的数值物理模拟

以某钢厂双长水口七流方坯中间包为研究对象,进行中间包优化研究。建立1∶4水模型并开展水模实验,对水模实验结果进行分析,研究导流孔位置和上仰角度对双长水口中间包流场的影响,选取最优的控流装置。同时,运用商业软件ANSYS Fluent对原型中间包和优化中间包进行流场和温度场耦合计算,并与水模型结果相互验证。结果表明,优化前后停留时间从127 s增至253 s,死区比例从57.13%减至24.10%,停留时间标准差从21.74减至10.87,浇注区纵截面浇注温度最大温差从4.7 K降至1.2 K,各流水口温差明显降低,中间包各水口一致性增加,流动更加均匀。

Pressure Wave and Fluid Velocity in a Bend-Mode Inkjet Nozzle with Double PZT Actuators

A new concept of bend-mode inkjet nozzle with double PZT (lead zirconate titanate) actuators has been designed and fabricated in the present study. Then the pressure wave and fluid velocity at the nozzle exit have been investigated. The complex pressure behavior inside the channel was solved numerically based on the narrow channel acoustic theory. The two PZTs attached to a rectangular channel were actuated sequentially by setting the waveforms of each PZT to be center-aligned with various pulse widths. As a result, the double PZT actuation is superior to the single PZT actuation in view of strong momentum force and fast dissipation of residual pressure. The maximum fluid velocity at the nozzle exit is observed when the respective pulse widths equal to their optimum pulse widths. The numerical results are supported by the experimental results with the fabricated inkjet device by measuring the speed of meniscus just out of the nozzle.

基于PIV的大豆蛋白液双枪喷涂速度场的研究

目的 为了在保证喷涂雾化表征均匀性的前提下实现宽幅覆膜,提高覆膜的效率,以期得到均匀一致的大豆蛋白覆膜。方法 利用粒子图像速度场仪(Particle Image Velocimetry,PIV),对不同干涉程度下的大豆蛋白液双枪喷涂雾化场进行拍摄,利用PIV和Origin软件处理图像,得到速度数据并对比。结果 随着双枪间偏转角的增大,基线上的平均速度减小;偏转角为0°时,两喷雾粒子流在干涉线处碰撞,少有透过干涉线的粒子;在不同偏转角下,基线上的速度峰值从大到小为偏转角7°时的速度峰值、偏转角0°时的速度峰值、偏转角15°时的速度峰值;当偏转角为0°时,随着液压的增大,基线上的第2个速度谷值会右移,并且会增大直至消去。结论 当偏转角为0°、液压为0.24 MPa时,在基线上干涉区域内的速度最均匀。

双腔室自振脉冲喷嘴空化射流数值模拟

以风琴管喷嘴为基础,串联一个谐振腔形成双腔室自激振荡脉冲喷嘴,利用Fluent对其流场进行数值模拟,分析射流靶距、二级谐振腔腔长比、腔径比的变化对空化射流流场的影响。结果表明:谐振腔尺寸过大或过小均会影响涡环结构的形成,进而影响空化效果。当谐振腔腔长比为0.77、腔径比为2.6时,谐振腔内涡环结构对称性好,轴向含气率高,射流速度较高,该结构利于清洗效率的提高。靶面滞止压力可对空化效果产生影响。当射流靶距较小时,在滞止压力的作用下二级谐振腔无涡环结构产生,轴向含气率较低。当靶距增加到18 mm时滞止压力产生的影响减小,轴向含气率明显提高,因此清洗靶距应至少为18 mm。但靶距的增加会降低射流到达靶面的动能,因此最佳靶距应取18 mm。

双电极熔体微分静电纺丝实验分析

基于多喷头阵列熔体微分电纺过程中高电压紊乱和纤维分布不均等问题,研发了双电极熔体微分静电纺丝技术。通过对单、双电极进行对比实验,分析了双电极结构对纤维数量和分布直径的影响,并得到了最佳的实验参数。实验结果表明,当单电极距喷头为200 mm、电压为70 kV时,纤维数量和分布直径分别为30根、16.5 mm。当双电极距喷头分别为20和200 mm,电压为30/40~10/60 kV时,与单电极相比,纤维数量增加了10%~80%,纤维分布直径增大了9%~54.5%。当双电极电压为22/48 kV时,纤维数量最多且分布直径达到最大,其值分别为54根和25.5 mm。可以通过控制上电极内圆直径和电压调节纤维沉积面积。为解决多喷头熔体静电纺丝过程中存在的问题提供了指导。

双炉膛双切圆电站锅炉水冷壁防高温腐蚀数值模拟研究

锅炉水冷壁高温腐蚀是影响大型火力发电机组安全、经济运行的主要因素之一。文中针对某国内1000 MW双切圆锅炉试运行期间左右墙水冷壁发生高温腐蚀的现象,通过Fluent数值模拟,分别研究了燃烧器高宽比和二次喷口摆动角度对水冷壁高温腐蚀的影响。模拟结果表明:锅炉在实际运行时应使用高宽比较小的燃烧器组合方式;二次风喷口在向上摆动15°时燃烧区域贴壁面处CO浓度均小于3%,氧气含量充足,可以有效降低水冷壁高温腐蚀的风险。

顺风流动下单双层喷嘴雾化特性的数值模拟研究

为研究顺风流动下单双层喷嘴的雾化特性,采用Fluent中离散相模型对顺风流动下单、双层喷嘴的雾化特性进行数值模拟,先将雾滴平均粒径的模拟值与实验值进行对比分析,验证模型的可靠性,再分析不同工况下单、双层喷嘴喷射出的雾滴群平均粒径及速度变化规律。结果表明:同一扰动风速及供水压力条件下,单层喷嘴比双层喷嘴喷射出的雾滴群平均粒径小;随扰动风速、供水压力的增大,单、双层喷嘴喷射出的雾滴群平均粒径均逐渐减小;扰动风速显著影响雾滴群的速度分布,扰动风速越大,单、双层喷嘴喷射出的雾滴群速度越大且雾滴群射程越远,整体呈现出大粒径雾滴先于小粒径雾滴沉降的趋势。

喷嘴特性对双旋流燃烧室出口温度分布影响的实验研究

本文以双旋流全环燃烧室为试验对象,在高温高压试验条件下,通过调整全环燃油喷嘴的流量离散度和径向位置来研究其对出口温度分布的影响。试验结果表明,当喷嘴燃油流量离散度控制在±4%以内时,采用简单的大、小流量喷嘴间隔搭配的方案即可保证出口温度分布的均匀性;当燃油流量离散度放大到4%~8%时,采用本实验研究的搭配方案仍可保证出口温度分布的均匀性;当燃油流量离散度放大到10%时,通过调整喷嘴搭配方案已经无法保证出口温度分布均匀性。燃油喷嘴径向位置较火焰筒头部中心线偏离旋流杯腔道高度的11.5%以内时,不影响出口温度分布的均匀性。

120 t双水口LF精炼钢包生产实践

针对双水口全精炼钢包内衬严重侵蚀,影响钢包安全使用、制约生产顺行的现状,对双水口全精炼钢包寿命提升进行研究。通过开发应用钢包内衬复合砌筑、精炼喷粉调渣、电极溅渣补包等技术手段,使双水口全精炼钢包寿命大幅提升,一次包龄由35.9次提高到53.7次。