喷油参数对共轨柴油机排放影响的试验研究

针对某款轻型车用柴油机的燃油系统,进行了油嘴伸出量和柴油机燃烧室的匹配选择。试验研究了在转速为1696r·min-1,转矩为146N·m的工况下,轨压、主喷正时、预喷射参数以及EGR对NOx、烟度及燃油消耗率的影响。结果表明:在1.4mm的喷油器垫片下的油嘴伸出量,烟度最好。在试验所研究的工况点下,增大轨压可有效改善燃油雾化特性,使得烟度和燃油消耗率降低,但NOx排放增多;推迟主喷正时可有效降低NOx的排放,这两个喷油参数可作为优化柴油机性能的重要指标。通过试验可知,柴油机存在一个最佳的主预喷间隔;随着预喷油量的增加,烟度和燃油消耗率逐渐增加,NOx呈现先减少后增加的趋势;EGR阀开度的增加使NOx明显减少,但EGR阀开度在30%之后,烟度开始明显恶化。     

喷油器结构对柴油机NO_X和碳烟排放影响的研究

通过对某四缸增压中冷柴油机进行不同工况下的排放对比试验,研究喷油器压力室、喷孔直径、油嘴伸出量和喷油器开启压力对柴油机排放特性的影响,为样机优化提供参考方案。试验表明:无压力室喷油器碳烟的生成量减小但NO_X的生成量会增加;除了2850r/min转速的中高负荷情况下,柴油机的NO_X生成量随着喷孔直径的减小而增大,碳烟的生成量则随着孔径的减小而减小;随着油嘴伸出量的增加,柴油机的NO_X生成量逐渐增大,碳烟的生成量逐渐减小;喷油器的开启压力的增加导致柴油机的NO_X生成量变大,但是碳烟生成量有所减少,并且转速越低,负荷越小时这种影响更明显。通过试验确定喷油器压力室的选择以及最佳喷油器孔径、开启压力、喷油嘴伸出量。     

均匀试验设计方法在柴油机多变量优化中的应用

在发动机模拟软件AVL boost上使用均匀试验设计方法安排了不同水平的喷孔直径、喷油压力、喷油提前角和燃烧室压缩比对柴油机性能影响的模拟试验。然后建立回归方程进行优化，模拟和优化结果的对比表明：均匀设计方法在大大减少试验次数的同时仍可获得对燃油消耗率、功率和NOx排放的精确预测，其在发动机模拟计算上的应用是可行的。     

试验设计方法在耐磨涂层材料中的应用

在对全面试验法、正交试验法和均匀设计法进行介绍的基础上,用正交试验设计安排了耐磨涂层的喷涂工艺,采用配方均匀设计确定了涂层材料的配比.     

活塞燃烧室结构对高负荷柴油机经济性和排放的影响

针对某高负荷柴油机开展了燃烧室结构设计与柴油机性能关联因素的研究。研究过程中,燃烧室高度和容积保持恒定,燃烧室凸台高度、锥度和喉口直径作为设计与评价变量。研究的三种燃烧室结构包括:标准燃烧室(A);增加凸台高度并且喉口采用敞口形式的燃烧室(B);具有与标准燃烧室相同凸台高度但减少了锥度并且喉口采用敞口形式的燃烧室(C)。对该三种燃烧室进行了数值模拟计算与柴油机实验对比工作。研究表明,具有较高凸台且喉口采用敞口形式的燃烧室促进了燃料与空气的混合,提高了柴油机的经济性,有效降低了柴油机排放。     

基于试验设计法的L形薄板弯曲回弹预测

用正交试验设计法和均匀试验设计法对L形薄板弯曲回弹进行预测。借助两种试验设计方法进行方案试验,利用ANSYS/LS-DYNA数值模拟得出各组方案中不同因素组合下的回弹量;通过直观分析、方差分析、回归分析和假设检验,得到各因素对回弹角的影响,找出取得最小回弹量的各因素水平的最优组合,获得试验范围内影响回弹的最佳工艺范围。结果表明,均匀试验设计法能够对回弹进行更有效的预测和控制。     

陶瓷纤维铝基复合材料在铝合金活塞燃烧室喉口的应用

本文针对高强化柴油机活塞燃烧室喉口开裂的失效问题,简要分析了喉口开裂的原因,提出对喉口进行局部强化的对应措施。研究了陶瓷纤维铝基复合材料对喉口性能的影响,对陶瓷纤维复合材料的制作过程进行了阐述,并进行了材料的性能对比和试验试验。经过对比,燃烧室喉口部位的复合材料比ZL109G基体材料金相组织更加细密均匀,具有更加优异的高温性能,高温抗拉强度明显提高。优良的高温性能可以提高活塞的耐高温负荷能力,满足中重型高强化柴油机对活塞喉口性能的需求。     

陶瓷纤维铝基复合材料在铝合金活塞燃烧室喉口的应用

本文针对高强化柴油机活塞燃烧室喉口开裂的失效问题,简要分析了喉口开裂的原因,提出对喉口进行局部强化的对应措施。研究了陶瓷纤维铝基复合材料对喉口性能的影响,对陶瓷纤维复合材料的制作过程进行了阐述,并进行了材料的性能对比和试验试验。经过对比,燃烧室喉口部位的复合材料比ZL109G基体材料金相组织更加细密均匀,具有更加优异的高温性能,高温抗拉强度明显提高。优良的高温性能可以提高活塞的耐高温负荷能力,满足中重型高强化柴油机对活塞喉口性能的需求。     

改进燃烧系统提高车用柴油机的性能

阐述了燃烧系统对发动机性能的影响；介绍了双ω型燃烧室；设计了与车用柴油机相匹配的双ω燃烧室；优化了喷油系统参数，列出了相应的试验研究成果。     

基于均匀设计法的L形板料弯曲优化设计

使用均匀设计法,对影响L形板料弯曲回弹的相关因素进行优化设计。借助均匀设计方法来安排试验方案,利用ANSYS/LS-DYNA的数值模拟得出各组方案中不同因素组合下的回弹量。通过求解多元线性和二次回归方程,得到各因素对回弹角的影响。对二次回归模型进行极值分析,得出取得最小回弹角的各因素水平的最优组合,并得到试验范围内影响回弹的最佳工艺范围,能够对回弹进行有效的预测和控制。     

A preliminary investigation of the design parameters of an air induction nozzle

In the present study, an experimental study on design parameters of an air induction nozzle was performed. These nozzles are capable of producing large size droplets, including microbubbles, which in turn results in high drift reduction. A magnified 2D version of an air induction nozzle was designed and manufactured. The manufactured geometries have the ability to be disassembled easily, thus several geometrical parameters are replaced sequentially. The effects of a venturi throat, air orifices and discharge orifice diameters along with the length of the mixing chamber are analyzed. Analysis of the parameters revealed their strength of prediction on the air liquid ratio and the nozzle performance.     

Investigation of design parameters for droplet generators driven by piezoelectric actuators

This paper presents a numerical analysis of a drop-on-demand (DOD) piezoelectric (PZT) actuated droplet generator. A finite difference numerical model was established to analyze the design parameters of droplet ejection. First, we discussed the influence of the driving conditions on the droplet ejection characteristics, such as the driving time and the driving volume change in the pressure chamber. The volume factor, an important design parameter, was proposed from the analysis. The ejected droplets can maintain the same ejection velocity at different nozzle diameters, as long as the volume factor remains the same. Two empirical formulas, based on the analysis data, are suitable for the design of PZT actuated droplet generator. The first empirical formula is a linear relationship between the droplet velocity and the volume factor with a slope of 0.3422 for different nozzle diameters. The second empirical formula defines the driving volume of PZT and nozzle diameter to eject the desired droplets. The geometrical design parameters of droplet generator, such as the nozzle thickness, the pressure chamber width and depth, as well as the driving conditions of the PZT actuator, are all included in the analysis. The sensitivity of geometrical design parameters which affect the droplet volume, the droplet velocity, and the lowest driving condition is established. The quantitative criterion for ejection of droplet, liquid jet, and no droplet is presented. The proposed empirical formula and figures provide easy-to-use tool for design of DOD PZT actuated droplet generators.     

普通机床加工发动机缸盖球形燃烧室的工艺试验

发动机缸盖是发动机的关键零部件.发动机缸盖的燃烧室容积,直接影响到发动机的工作性能,所以在发动机缸盖制造过程中,最终必须保证发动机缸盖燃烧室的形状、表面粗糙度、尺寸精度、容积等一系列参数,从而保证发动机总机性能.     

喷水减温阀离心喷嘴雾化性能的优化研究

为了探索喷水减温阀喷嘴结构参数变化对其雾化效果的影响,优化喷嘴结构参数,根据Fluent软件VOF模块对喷水减温调节阀的离心喷嘴进行气-液两相仿真分析。以喷嘴出口直径、旋流槽倾斜角、旋流室收缩角作为优化因素,以雾化锥角、流量系数作为雾化性能的评价指标,进行正交实验设计。基于响应面法建立雾化锥角和流量系数的代理模型,再运用粒子群优化算法对代理模型进行寻优,得到一个最优结构参数。结果表明:当出口直径为2.55 mm,旋流槽角度为40°,旋流室角度为110°时,雾化性能得到最优,雾化锥角比原模型增大17.7％,流量系数增大32.53％,为喷嘴的设计提供了一个新的方案。     

Effect of nozzle geometry for swirl type twin-fluid water mist nozzle on the spray characteristic

Experimental investigations on the atomization characteristics of twin-fluid water mist nozzle were conducted using particle image velocimetry (PIV) system and particle motion analysis system (PMAS). The twin-fluid water mist nozzles with swirlers designed two types of swirl angles such as 0°, 90° and three different size nozzle hole diameters such as 0.5mm, 1mm, 1.5mm were employed. The experiments were carried out by the injection pressure of water and air divided into 1bar, 2bar respectively. The droplet size of the spray was measured using PMAS. The velocity and turbulence intensity were measured using PIV. The velocity, turbulence intensity and SMD distributions of the sprays were measured along the centerline and radial direction. As the experimental results, swirl angle controlled to droplet sizes. It was found that SMD distribution decreases with the increase of swirl angle. The developed twin-fluid water mist nozzle was satisfied to the criteria of NFPA 750, Class 1. It was proven that the developed nozzle under low pressures could be applied to fire protection system.     

柴油机燃烧室匹配参数对撞壁喷雾特性的影响

利用高速纹影摄像技术,研究了喷油器喷孔角度、喷孔与活塞顶面间的撞壁距离、燃烧室缩口半径和凸台夹角对柴油撞击燃烧室壁面后喷雾特性的影响。研究结果表明,试验条件下适宜的喷孔角度为75°,增大喷孔角度可以促进喷雾撞壁后的油气混合,但是喷孔角度过大会增加油束撞击气缸盖和气缸套的风险;适宜的撞壁距离为4.2mm,即压缩上止点前15°CA（CA指曲轴转角）,较小的撞壁距离会促进喷雾液滴在凹坑区域的碰撞与黏结,而较大的撞壁距离不利于燃烧室中心区域的空气利用;此外,适当增大缩口半径可以促进燃油与空气的混合,减小燃烧室壁面的燃油湿壁面积;改变凸台夹角可以控制撞壁后喷雾在燃烧室中心区域的扩散速度。     

Measurement and analysis of injection characteristics among each nozzle hole within a heavy-duty diesel engine

The mass flow rate from each injector nozzle hole of a diesel engine influences the distribution, atomization, and combustion of fuel in the chamber. Thus affecting the power, the fuel economy, and the emission quality of the diesel engine. A spray momentum flux test bench was built and used to measure the injection rate from each nozzle hole of a multi-hole nozzle in this study. Selected force sensors used for data acquisition were one of the integral parts of the set-up. The influence of the force sensors’ installed position (location in the set-up) on measured results, were analyzed and the optimum position that ensures independence of the results, determined. Additionally, the effects of injection pressure, injection pulse width and injection hole diameter on the injection characteristics were also investigated. Furthermore, in this research, the reliability and robustness of Strain sensor and Piezoelectric sensors were analyzed with regards to their response. The analysis showed that, strain sensors have weak dynamic response characteristic compared to piezoelectric sensors also, the measured result obtained from strain sensors fluctuated greatly. Piezoelectric force sensor gave a more reliable and stable measurement, comparatively. The accuracy of the results were affected by the installation position of the sensors. A distance of 16 mm (between nozzle hole exit and sensor surface) was determined to be adequate for the acquisition of reliable experimental data. As the injection pressure gets higher (during injection), the rate of mass flow increased, the average cycle-to-cycle variation coefficient and nozzle-to-nozzle variability coefficient of injection quantity decreased. Hence, improving the consistency of each cycle and the uniformity of each hole. In addition, increasing the injection pulse width decreased the average cycle-to-cycle variation coefficient. Also, nozzle-to-nozzle variability coefficient had minimal or no influence with regards to injection pressure. At 80 MPa, the uniformity of injection from the multi-hole nozzle improved significantly. In summary, the larger the hole diameters, the higher the maximum value of mass flow rate and the fuel injection quantity.     

Analysis upon fuel injection quantity variation of common rail system for diesel engines

Fuel injection quantity variation of common rail system has effect on the stability and reliability of diesel engines. For purpose of investigating the influence rule and mechanism of fuel injection quantity variation caused by parameters, taking account of the influence of fuel physical properties on dynamic injection characteristics of the system, a bond graph model of common rail injector has been proposed based on bond graph methodology and the state equations of the system are obtained. Comparisons between calculated fuel injection quantities by the numerical model and experimental measurements at different rail pressures and injection pulse widths indicate that the developed model can reasonably predict the fuel injection quantity characteristic of the system. Fuel injection quantity variation characteristics caused by the parameters of common rail injector have been analyzed in entire operating conditions. The selected parameters are delivery chamber diameter, needle seat semi-angle, needle cone semi-angle, ball valve seat semi-angle, nozzle hole diameter, inlet orifice diameter and outlet orifice diameter. The variation rules of quantitative percentages are obtained by quantitative analysis upon fuel injection quantity variation influential factors. It is concluded that ball valve seat semi-angle, nozzle hole diameter, inlet orifice diameter and outlet orifice diameter have the most significant effect on fuel injection quantity variation, and the followed are delivery chamber diameter and needle seat semi-angle. In addition, needle cone semi-angle also results in the variation of fuel injection quantity, but the effect is insignificant.

     

大功率柴油机燃烧室优化及其与喷油嘴的匹配试验

运用仿真与试验相结合的方法,利用KIVA-3软件对燃烧室进行了优化研究,确定燃烧室的优选方案。并在一台模拟增压单缸机上对燃烧室的优选方案与不同方案喷油嘴进行优化匹配试验,确定喷油嘴最佳方案。结果表明:采用燃烧室B和8×Ф0.42 mm喷油嘴,可以达到研究目的。     

高空、低速、低雷诺数对发动机部件及整机性能的影响研究

为研究FWS-9发动机作为高空无人飞行平台动力装置的可行性,在对发动机旋转部件(压气机、涡轮)雷诺数修正的基础上,研究了高空、低速、低雷诺数对发动机部件(风扇、压气机、主燃烧室和涡轮)和整机性能、稳定性的影响规律。