共轨系统小压力室喷油嘴喷雾特性

柴油机喷油嘴是燃油系统和燃烧室之间的关键接口,对燃油雾化非常重要．设计加工了喷雾需要的单孔喷油嘴,检测了喷孔的入口和出口尺寸．喷油嘴经过液体挤乐研磨处理,并测试了喷油嘴在挤压研磨前后10MPa下的高斥流量．液体挤压研磨能够提高流量系数10％～15％．测得给定工况下试验喷油嘴的喷油规律和针阀升程,用Matlab编程得到的...     

喷油嘴喷孔挤压研磨及装机试验分析

为了解决喷油嘴流量低导致的燃油消耗率高和排气温度高等问题,采用KYM-2型喷油孔液体挤压研磨机进行了喷油嘴喷孔挤压研磨试验,并在XCW8200ZC-10型柴油机上进行了推进特性试验。喷油嘴喷孔挤压研磨及装机试验结果表明:挤压研磨压力为7 MPa,挤压研磨时间为20 s时,流量由挤压前的3.380 L/min增加至4.117 L/min,流量系数由挤压前的0.69提高至0.84,流量分散度由挤压前的-6.7%～5.8%缩小至-4.0%～3.5%。在标定工况,挤压研磨后的燃油消耗率比挤压研磨前的低5 g/(kW·h),挤压研磨后的总管排气温度比挤压研磨前的低18℃。     

机车柴油机用喷油嘴偶件流量的试验研究

通过稳态高压液体流量的试验,初步掌握了机车柴油机用喷油嘴偶件的流量系数和流量分散度的现状,分析了影响喷油嘴偶件流量的因素。介绍了应用液体挤压研磨技术提高机车柴油机用喷油嘴偶件流量的效果。     

多孔式喷油嘴喷孔入口处圆角探讨

<正> 1 前言 凡从事柴油机及燃油喷射系统工作的科技工作者都知道喷油嘴流量特性对柴油机性能有直接影响。多年来,不断看到有关资料介绍国内外同行研究喷油嘴喷孔入口处圆角效应对喷油嘴流量特性的影响。近年来获悉美国挤压研磨公司可对喷油嘴采用挤压研磨新     

喷油嘴喷孔液体挤压研磨工艺研究

通过对喷油嘴喷孔液体挤压研磨加工工作原理和磨料介质的流变特性和运动规律的分析，探讨了喷油嘴挤压研磨加工的工艺特点和工艺参数，为进一步控制喷油嘴的流量和流量系数提供了经验。     

双排喷孔液体挤压研磨压力的研究

通过不同等级压力的试验,研究了液体挤压研磨对双排喷油嘴喷孔形状的影响,结果显示,孔径随着研磨压力的减小而减小,孔径分布随着研磨压力的减小而更集中;奇数孔与偶数孔孔径的差值随着研磨压力的减小而明显减小;外孔圆度最大值及奇偶孔圆度均值均随着压力的降低而改善,在高压研磨加工双排喷油孔时比较合适的研磨压力是7.0 MPa左右.     

提高190柴油机喷油嘴性能的试验研究

本文通过试验研究,对１９０系列柴油机喷油嘴的设计和加工工艺进行了大量改进,使喷油嘴性能和柴油机燃油耗率获得了明显改善．     

液体挤压研磨技术在喷油嘴喷孔加工中的应用

介绍了液体挤压研磨新技术的原理和设备，经过液体研磨后，喷油嘴流量提高，流量系数提高，流量分散度缩小，发动机性能和排放得到明显改善。     

加工压力对喷油器喷孔研磨过程的影响

针对某喷油器对喷孔挤压研磨过程进行CFD模拟计算,对比分析不同加工压力对研磨结果的影响。结果表明:不同加工压力下的磨蚀分布基本一致,各喷孔入口处的磨蚀都明显高于喷孔壁面上的磨蚀,喷孔壁面的磨蚀主要分布在出口处;加工压力增加使流场压力、磨粒速度和湍动能增大,流动更为强烈,磨削作用增强,导致各处平均磨蚀率随之增大。     

针阀体喷孔去毛刺方法对喷孔流量的影响

在用钻削方法加工针阀体喷孔时，喷孔口的毛刺不可避免。毛刺的存在会降低喷孔的燃油流速，减小喷孔的流量，影响柴油机的工作性能，因此针阀体在插配之前必须去毛刺。文章介绍了传统方法去毛刺、研磨压力室去毛刺、电解压力室去毛刺、喷孔挤压珩磨去毛刺4种去毛刺方法以及它们各自的特点，着重分析了电解压力室去毛刺、喷孔挤压珩磨去毛刺对针阀体流量的影响，认为用电解压力室方法去毛刺既能够提高喷油嘴流量，经济性又好，是一种比较有效的工艺方法。     

Experimental and numerical investigation of circularly lobed nozzle with/without central plug

The experimental rig was established for the pumping performance investigation of a circularly lobed nozzle with a central plug, and of the same nozzle without a central plug for comparison. Seven different cylindrical mixers were designed to match the circularly lobed nozzle. Results show that the central plug increases the pumping ratio of the secondary mass flow rate to the primary mass flow rate about 60-70% over the same lobed nozzle without a central plug, and the total pressure prior to flow's entry into circularly lobed nozzle increased about 0.8-1.0% over the same lobed nozzle without a central plug. In order to know the mixing process between the primary and the secondary flows, in addition, a numerical procedure was developed to solve the incompressible Navier-Stokes equations in a curvilinear nonorthogonal coordinate. The numerical results show that there are great differences in the thermal mixing process, of the case with a central plug in which the low temperature contour lines in the exit cross-section of cylindrical mixer can reach the central line of the mixer, from the case without a central plug in which the elevated temperature contour lines in the exit cross-section of cylindrical mixer still occupy the central zone of the mixer. This was the fundamental reason why the thermal mixing efficiency of the lobed nozzle with a central plug was much more than that of without a central plug. Lastly, good agreements of temperature and axial velocity component in the exit cross-section of the mixer had been observed between the numerical results and the measured ones.     

Investigation of spray cooling: Effect of different heater surfaces under acceleration

Spray cooling characteristics under acceleration conditions for different heat transfer surfaces were experimentally investigated with the aid of an acceleration test bench. Three heater surfaces tested were the flat surface, straight fin surface and porous tunnel surface. Water was used as the coolant and sprayed onto the heater surface at various nozzle heights by nozzles having different flow rates. The results of the fundamental studies show that for all the three surfaces, flow rate as well as nozzle height affects the spray cooling performance under the acceleration condition just like it does under the stationary condition. The influence of acceleration for the three heater surfaces is different and for one specific surface the effect of acceleration is also different due to the change in flow rate or nozzle height. According to the comparison results of the heat transfer performance for three surfaces under acceleration condition, it is observed that the porous tunnel surface has the best performance in all tests, followed by the flat surface in most tests. While for a certain case with a low flow rate and low nozzle height, the spray cooling capability for straight fin surface is better than flat surface.     

CFD simulations of premixed hydrogen combustion using the Eddy Dissipation and the Turbulent Flame Closure models

This paper presents a CFD simulation of premixed combustion tests, and centers around a comparison between the classical Eddy Dissipation Model (EDM) and the more sophisticated Turbulent Flame Closure (TFC) model. The chosen tests relate to hydrogen-air deflagration experiments in the THAI and ENACCEF facilities, featuring respectively slow and fast dynamics.Validation of the models is accomplished by comparing model predictions against important measured combustion parameters (flame velocity and spatial propagation, pressure history, spectra, etc.). We follow CFD Best Practice Guidelines, in particular by conducting systematic mesh and time-step sensitivity studies.Both default models predict combustion evolution reasonably well in all tests studied. For the ENACCEF dual compartment experiments, the flame propagation features several dynamical phases, and the TFC model using the progress variable approach reproduces better than the EDM the flame velocity evolution, which leads to better estimation of the temporal gradient of pressure. The better performance of the TFC model comes however at the expense of a larger computational effort, i.e. larger meshes and smaller time steps. This observed trend in 2D geometries is likely to be enhanced in 3D settings.     

Study of flow and combustion characteristics of optimized low swirl premixed nozzle for micro gas turbine

With the micro gas turbine is used more and more widely, the operating conditions become complex and fluctuating which impacts the environmental friendliness of combustor. In this work, a low swirl premixed nozzle (LSPN) is designed based on the original premixed nozzle (OPN) of a 60 kW micro gas turbine, in order to adapt the flexibility of load and operating environment by improving the mixing performance of fuel and air. The flow and combustion characteristics of LSPN and OPN fed by natural gas is numerically studied using the standard k-ε model and the combined Finite Rate Chemistry/Eddy Dissipation Model (FRC/EDM) under various operating conditions. The results show that the mixing performance of air and fuel in LSPN has been improved. The flow unmixedness in LSPN is always smaller than OPN, and it is 41.74% lower at the outlet of the nozzle. While the equivalence ratio decreases, the mean temperature in the combustor decline. Furthermore, under the majority of operating conditions, the emission performance of LSPN is better than OPN.     

柴油机喷油器喷孔磨粒流加工过程中颗粒形状影响的数值模拟

以喷油器喷孔为对象,基于欧拉-拉格朗日法和磨蚀模型对磨粒流研磨过程中的流场及颗粒运动进行了数值模拟,分别得出采用不同形状颗粒时的动压力、湍流动能、颗粒速度、磨蚀速率,探究了颗粒形状因子对研磨结果的影响。研究表明,磨蚀速率同颗粒形状因子成反比关系,采用形状因子较小的颗粒可加快研磨速度,形状因子为0.3的颗粒在喷孔入口处的磨蚀速率最大,比形状因子为0.7的磨蚀速率高出86.6%,颗粒形状对工件表面的磨蚀位置也有较大影响。     

CFB锅炉风帽改造及试验研究

钟罩式风帽存在的问题与现场安装、运行控制和日常检修息息相关,文中针对某厂循环流化床锅炉钟罩式风帽存在的问题进行分析研究,改造应用新型耐磨防漏渣风帽,完成了布风板阻力试验和料层阻力试验.结果显示,改造后风室漏渣和流化不均彻底消除,改造取得了圆满成功,相关研究可为今后循环流化床锅炉同类改造参考.     

Effect of silicone oil on solid propellant combustion in small motors

The feasibility of reducing troublesome nozzle blockage (by condensation deposits) in laboratory-scale solid rockets by addition of a silicone oil as a propellant ingredient was explored experimentally. An aluminized composite propellant and its counterpart with 1% silicone oil replacing part of the binder were fired in a 63.5 mm diameter, end-burning, all-metal burner. Pressure-time histories were recorded for all of the tests by a Taber gauge mounted at the downstream end of the chamber; temperature-time data at the nozzle throat were obtained in some of the runs by thermocouples having junctions positioned at the wall but insulated from the metal. Deposition of condensables on the nozzle walls causing a progressive increase in the chamber pressure with time was noted. The fraction of firings exhibiting practically no condensation was 59% with silicone and 32% without. On the average, temperature readings at the nozzle throat were higher with the silicone propellants. Although various phenomena may contribute to these findings, the results are not understood completely.     

柴油机喷油器结构参数与磨料流加工效果关联的研究

基于磨蚀模型和多相流离散相模型建立了柴油机喷油器磨料流加工过程的CFD计算模型。在验证基础模型的有效性后,分别针对喷孔直径、喷孔锥角和交点位置三种结构参数进行变参数模拟计算。通过对加工域颗粒流速、湍流强度和磨蚀率的分析,获得了喷油器主要结构参数对液力研磨加工的影响机理:喷孔直径和喷雾锥度的变化对喷孔壁面磨蚀量的影响较大,随着两者的增大,喷孔壁面的磨蚀量有所增加;交点位置由上至下的变化对喷孔壁面磨蚀量的影响较小,但是喷孔入口处磨蚀量有所增加。     

Studies on the fabrication of metallic bipolar plates—Using micro electrical discharge machining milling

Owed to the advantages of highly precise and flexible machining, micro electrical discharge machining milling (micro EDM milling) can machine higher aspect ratio micro flow channels than the micro flow channels made from etching or deposition techniques, which have aspect ratio of only 0.5-0.7.This study reports on the production of micro flow channels in metallic bipolar plates, using micro EDM milling. Through the use of micro EDM milling with tungsten carbide electrodes, this study succeed in machining channels with a depth and rib width of 500 μm, and height of 300 μm, 600 μm (aspect ratio of 0.6 and 1.2), respectively, in a reaction area 20 mm × 20 mm, on 50 mm × 50 mm × 1 mm SUS 316L stainless steel.In single cell tests, the cell performance in metallic bipolar plates with aspect ratio of 1.2 is higher than that of other tests, and this result shows that the aspect ratio can promote performance of micro fuel cells. Moreover, under the same condition regarding cell size, single cell performance in metallic bipolar plates of aspect ratio of 1.2 with micro EDM milling in this study is higher than the performance in metallic bipolar plates with electroforming or electrochemical machining techniques, and the metallic bipolar plate can promote power per unit volume.