Numerical investigation of dynamic characteristics of dual throat nozzle and bypass dual throat nozzle in thrust vectoring starting process

The Bypass Dual Throat Nozzle(BDTN)is a novel fluidic Thrust Vectoring(TV)nozzle,it switches to TV state by opening the valve in the bypass.To greatly manipulate the BDTN,the dynamic characteristics in the TV starting process should be analyzed.This paper conducts numerical simulations to grasp the variation processes of performances and the flow field evolution of BDTN and Dual Throat Nozzle(DTN).The dynamic responses of TV starting in typical DTN models are investigated at first.Then,the TV starting processes of BDTN in different Nozzle Pressure Ratio(NPR)conditions are simulated,and the valve opening durations(T)are also considered.Before the expected TV direction is achieved in the DTN,the jet is deflected to the opposite direction at the beginning of the dynamic process,which is called the reverse TV phenomenon.However,this phenomenon disappears in the BDTN.The larger injection width of DTN intensifies unsteady oscillations,and the reverse TV phenomenon is strengthened.In the BDTN,T determines the delay degree of performance variations compared to the static results,which is called hysteresis effect.At NPR=10,the hysteresis affects the final stable performance of BDTN.This study analyses the dynamic characteristics in DTN and BDTN,laying a foundation for further design of nozzles and control strategies.

Analysis of the Flow Field Characteristics Associated with the Dynamic Rock Breaking Process Induced by a Multi-Hole Combined External Rotary Bit

The characteristics of the flow field associated with a multi-hole combined external rotary bit have been studied by means of numerical simulation in the framework of an RNG k-εturbulence model,and compared with the results of dedicated rock breaking drilling experiments.The numerical results show that the nozzle velocity and dynamic pressure of the nozzle decrease with an increase in the jet distance,and the axial velocity of the nozzle decays regularly with an increase in the dimensionless jet distance.Moreover,the axial velocity related to the nozzle with inclination angle 20°and 30°can produce a higher hole depth,while the radial velocity of the nozzle with 60°inclination can enlarge the hole diameter.The outcomes of the CFD simulations are consistent with the actual dynamic rock breaking and pore forming process,which lends credence to the present results and indicates that they could be used as a reference for the future optimization of systems based on the multi-hole combined external rotary bit technology.

Nosing process of empty and foam-filled circular metal tubes on semispherical die by theoretical and experimental investigations

Nosing process of circular metal tubes in empty and polyurethane foam-filled conditions on a semispherical rigid die was analyzed by theoretical and experimental methods.A new theoretical model of plastic deformation of circular metal tubes was demonstrated during the nosing process on a rigid semispherical die.Based on the analytical model,some theoretical relations were calculated to estimate instantaneous forming load and dissipated energy of empty and foam-filled circular metal tubes versus axial displacement.Some circular brazen and aluminum tubes were prepared and shaped into semispherical nosed nozzles to verify the present theory.Comparison of theoretical predictions and the corresponding experimental measurements reveals that predicted load?displacement and dissipated energy?displacement diagrams by theoretical formulas have a good correlation with the corresponding experimental curves and it proves verity of the theory.Also,the present theory shows that dissipated energy and axial load of empty tubes depend on material type,wall thickness and diameter of the tubes and they are independent of tube initial length.Furthermore,the experimental results show that the presence of polyethylene Teflon-constraints increases ultimate axial displacement of the forming process.

Research on the application of the wet scrubber on the BSSF slag processing system at Baosteel

Based on the analysis results of the dust size distribution of flue gas from Baosteel＇s short-flow （BSSF） slag processing system and the mechanism of the wet scrubber,a wet scrubber system was designed and installed in the No. 1 BSSF slag processing system at Baosteel. The results show that the dust removal efficiency of the previous system that had conventional water nozzles was only 69% with a liquid-gas ratio of 0.79 L/m^3 ,while the dust removal efficiency reached 94% when three sets of high-efficiency dual phase spray guns were installed inside both the flue and the chimney. For the latter system,the liquid-gas ratio was 0. 84 L/m^3 ,and the dust concentration in the cleaned emissions reduced to less than 40 mg/m^3.

滤棒直接加香装置改进设计研究

近年来滤棒加香技术由于具有不发生热降解、添加香料种类多样等优点,已成为烟草企业重要的研究方向。然而,滤棒加香工艺中存在滤棒喷嘴易堵塞和香料加注流量不稳定等问题。本研究对滤棒直接加香装置的结构和工艺流程进行了优化,解决了喷嘴易堵塞等问题,并通过定压控制保证了香料加注流量的稳定性。同时本研究采用双称重传感器差值的方法,对小流量的测量起到一定补充作用,提高了滤棒加香工艺的精度,本研究为滤棒加香技术的发展和应用提供了参考。

航空导向器三维测点处理与喉道面积精确计算

导向器是航空发动机的重要部件,喉道面积作为其关键参数直接影响发动机动力性能。针对导向器喉道面积现有测量方法效率低、喉道面积估计不准的问题,提出了导向器三维测点处理与喉道面积精确计算的新方法,并在多联叶片导向器样件上开展了该方法与三坐标测量计算方法的对比实验。实验结果表明,所提方法得到的喉道面积更精确,且多次测量计算结果具有较高的一致性。

Analysis and control of the compaction force in the composite prepreg tape winding process for rocket motor nozzles

In the process of composite prepreg tape winding,the compaction force could influence the quality of winding products.According to the analysis and experiments,during the winding process of a rocket motor nozzle aft exit cone with a winding angle,there would be an error between the deposition speed of tape layers and the feeding speed of the compaction roller,which could influence the compaction force.Both a lack of compaction and overcompaction related to the feeding of the compaction roller could result in defects of winding nozzles.Thus,a flexible winding system has been developed for rocket motor nozzle winding.In the system,feeding of the compaction roller could be adjusted in real time to achieve an invariable compaction force.According to experiments,the force deformation model of the winding tape is a time-varying system.Thus,a forgetting factor recursive least square based parameter estimation proportional-integral-differential（PID）controller has been developed,which could estimate the time-varying parameter and control the compaction force by adjusting the feeding of the compaction roller during the winding process.According to the experimental results,a winding nozzle with fewer voids and a smooth surface could be wounded by the invariable compaction force in the flexible winding system.

Comparisons of nozzle orifice processing methods using synchrotron X-ray micro-tomography

Based on the high flux synchrotron X-ray of the Shanghai Synchrotron Radiation Facility (SSRF), high precision 3D digital models of diesel nozzle tips have been established by X-ray micro-tomography technology, which reveal the internal surfaces and structures of orifices. To analyze the machining precision and characteristics of orifice processing methods, an ap- proach is presented based on the parameters of the internal structures of nozzle orifices, including the nozzle diameter, the orifice inner surface waviness, the eccentricity distance and the angle between orifices. Using this approach, two kinds of nozzle orifice processing methods, computerized numerical control drilling and electric discharge machining, have been studied and compared. The results show that this approach enables a simple, direct, and comprehensive contrastive analysis of nozzle orifice processing methods. When processing a single orifice, the electric discharge machining method has obvious advantages. However, when there are multiple orifices, the error levels of the two methods are similar in relation to the symmetry of distribution of the orifices.

烟草制丝线香糖料喷嘴雾化效果在线监测装置的研究应用

为有效监视烟草制丝线加香加料雾化效果,避免因雾化不均给产品质量带来风险,通过设计一种香糖料喷嘴雾化效果在线监测装置,实现实时对加香加料喷嘴雾化效果进行判断。结果表明:该装置可在线对滚筒内喷嘴雾化情况进行实时有效监测,及时发现并警示喷嘴雾化的异常情况,有效提高卷烟加香加料的稳定性和均匀性,稳定烟丝质量,保障卷烟品质。

某滑梯喷嘴组件加工工艺研究

针对应急撤离滑梯喷嘴组件采用常规手工钨极氩弧焊易存在变形、烧穿、焊瘤缺陷等问题,通过对喷嘴组件加工工艺分析研究,采用多种加工工艺进行试验筛选,开发了高频脉冲弧焊和真空钎焊等方法,保证了喷嘴组件焊接质量,解决了型号研制的加工瓶颈。同时,通过对几种加工方法进行对比分析,确定了不同产量需求下的加工工艺措施,为滑梯喷嘴组件的高质量制造提供了解决方案。

陶瓷片密封水嘴重金属释出规律及除铅工艺影响

目的目前国内缺乏陶瓷片密封水嘴的重金属析放规律的系统研究,同时水嘴生产企业也缺乏相关知识,因此有必要对此进行研究,为水嘴产业的绿色可持续发展提供科学依据。方法本研究通过实验室模拟方法,采用电感耦合等离子体质谱仪对水嘴重金属污染物析出量进行分析试验,系统地研究了陶瓷片密封水嘴中重金属污染物的析出规律。结果通过测试分析表面水嘴材料的材质也决定重金属污染物析出种类,浸泡时间和水质无机盐浓度与重金属析出量成正比。铅黄铜水嘴通过除铅工艺,有效降低铅、铬重金属析出量;铅析出量降低81%~86%,铬析出量降低52%~56%。结论企业可根据自身情况选择合适的材质及工艺生产水嘴。消费者应根据使用情况避免接触到过量重金属。

喷头综合性能精密测试试验台的研制

为精密测试喷头的综合性能,研制了喷头综合性能精密测试试验台.试验台能够精确测量现场温度、压力、总流量、各分流量及喷雾角等参数.通过数据采集网络采集数据,多片采集卡通过RS485总线连接,并通过专门开发的数控系统与上位管理机相连.数控系统的任务是对采集数据进行初步处理并把数据传输给上位管理机,配合上位机完成整个控制任务,也可独立完成各项控制功能.喷雾角的测量是通过图像处理技术实现的.在数据处理过程中,应用了数据融合技术、神经网络技术及分段处理技术,因而提高了采集数据的精度.

RESS法制备超细萘粒子

采用常规、简便的喷射装置,建立了一套超临界溶液快速膨胀(Rapid Expansion of Supercritical Solutions,RESS)实验装置。该装置能有效地防止堵塞。以CO2为溶剂,萘为溶质,考察了喷嘴直径及收集距离对沉积微粒粒径的影响,研究了在不同的收集距离时粒径随溶液浓度的变化规律。结果表明喷嘴直径增大将使产物粒子粒径增大;在50mm的范围内,产物粒径随着收集距离的增加而明显增加,结果也显示出RESS产物是通过更小粒子之间的碰撞凝结而生长。当收集距离较大时,晶体的生长过程相比于晶核的形成过程对沉积微粒的粒径影响更大,故粒子粒径随溶液浓度增加而增大;当收集距离较小时,晶核的形成过程占主导地位,因此产物粒径随溶液浓度的增加而减小,符合经典成核理论。

金刚石钻头可再生水口的试验

从仿生学的角度,依据脱皮动物的脱皮特性,设计一种可再生水口,用于增加金刚石钻头工作层的高度,进而延长钻头寿命。在可再生水口的加工方法上,首先利用冷压法把含有金刚石的胎体粉料冷压成型,然后组装在模具中,在特定的温度和压力下进行热压烧结,成功获得了具有可再生水口的小口径金刚石钻头;并在此基础上加工了Φ59mm钻头,模拟野外条件进行室内试验。结果表明:选用特定的水口材料,可以成功实现水口的可再生,为长寿命金刚石取心钻头的研制提供了一种新的思路。

低压射流不同喷嘴参数及压力下破碎过程实验

研究了不同低压下喷头喷嘴直径和喷嘴锥角对射流破碎的影响。采用高速摄像仪对低压圆柱射流的射流核心长度和射流破碎长度进行实验,测量了不同喷嘴结构的流量、射程和末端水滴直径。结果表明:同一压力下,当喷嘴锥角不变时,随着喷嘴直径的增大,喷头流量、射程和喷头末端水滴直径都变大,射流核心长度和破碎长度均增大;当喷嘴直径不变时,随着喷嘴锥角的增大,喷头流量逐渐减小,而喷头射程呈先增大后减小趋势,喷头末端水滴直径也变大,射流核心长度逐渐减小,射流破碎长度先减小后增大。综合考虑射程和雾化效果,直径为5 mm、锥角为45°的喷嘴为最优选择。同时通过对不同Re数和We数的实验和分析,给出了适合低压喷嘴的两种射流特征长度的拟合关联式。

四喷嘴气化炉烧嘴接管关键加工工艺技术研究

根据四喷嘴气化炉烧嘴接管的结构特点与技术要求,分析烧嘴接管的装配和加工上的技术难点,将烧嘴接管的八角垫环槽精加工列为关键工序,通过工艺技术研究,选取合适的数控加工设备和设计专用非标刀具,并针对加工过程中发现的问题加以改进,最终取得了较好的加工效果。

网络器与网络加工关系的研讨

通过对圆形丝道１２种网络器的研究，阐述了网络器丝道与气道的截面积及其比值与喂入率、空气压力及网络度之间的关系。提出了网络器的特性曲线及控制网络度的方法。通过该曲线可选择和确定网络器的尺寸参数，对确定的网络器可选择和确定工艺参数。

半干半湿法烟气脱硫雾化增湿设计

烟气增湿对半干半湿法烟气脱硫起着关键作用。本文分析了空气雾化效果优于机械雾化效果;计算了FM10型空气喷嘴雾化粒径可满足给定烟气条件下的蒸发粒径;烟气流中雾羽角度收缩,喷嘴均匀布置于烟道,避免湿壁;烟气增湿后,袋式除尘器需采取良好的保温措施,应选用表面处理的易清灰滤料,圆筒状滤袋。

气枪喷嘴高速射流的除水效率研究

为揭示喷嘴除水的机理并进而对气枪喷嘴进行改进和优化设计 ,本文提出了利用图像分析处理对小尺度气枪喷嘴高速冲击射流的除水效率的研究方法。该方法将有效除水面积作为衡量喷嘴除水效率的标准 ,从而实现了对喷嘴整体除水效率的定量测量 ,并利用该方法对影响气枪喷嘴除水效率的各种因素 (一次侧压力、喷嘴到平板的距离和射流攻角 )进行了研究 ,并将实验结果与用热线风速仪及总压探头测量的结果进行了比较 。

节省光刻胶的超声雾化喷涂工艺雾锥特性研究

光刻胶在集成电路(Integrated circuit,IC)制造、微机电系统(Micro electro-mechanical systems,MEMS)等工艺中广泛使用,价格昂贵、有毒。由于传统光刻胶薄膜制备多采用旋涂工艺,约95%的光刻胶浪费,且无害化处置成本高。为此,提高光刻胶的利用率一直是涂胶工艺追逐的目标之一。针对节省光刻胶的超声雾化喷涂薄膜制备工艺面临的薄膜均匀性问题,在自行开发的100 kHz的超声雾化喷嘴的基础上,通过分析载气的流场分布,建立雾化液滴在旋转、对称载气流场中的受力模型和碰撞模型,提出超声雾化液滴输运的数值模拟计算流程。超声雾化液滴输运的数值模拟有效地描述了供气流量、供液流量以及雾锥截面高度对雾锥液滴粒径和液滴浓度分布的影响。利用对AZ4999光刻胶雾锥特性的分析,在满足喷涂生产率的前提下,进行304.8 mm晶圆实际喷涂试验。试验结果表明超声雾化喷嘴不仅能够有效地实现光刻胶薄膜制备均匀性,而且较旋涂工艺节约80%以上的光刻胶,光刻胶利用率高。