Experimental study of a heavy fuel oil atomization by pressure-swirl injector in the application of entrained flow gasifier

The available SMD(Sauter mean diameter) correlations on pressure-swirl injectors predict droplet sizing very different from each other, especially for heavy fuels. Also there was a lack in the literature for comparing available correlations. So an experimental study was conducted on a heavy fuel oil(HFO) spray, Mazut 380. A pressure swirl injector was designed and fabricated. The experiments for Mazut at 40℃ and 80℃ were compared with the results for water, including spray half cone angle, breakup length and mean droplet diameter,at different injection pressures. Lower spray angle, higher breakup length and larger droplets were observed for lower injection pressures and higher liquid viscosity. SMD was about 75 μm for water and about 87 μm for Mazut at 80℃. The results for droplet mean diameter were also compared with correlations from previous studies on pressure swirl atomizers. The SMD results show that for water spray, LISA method was in good agreement,also Babu and Ballester correlations were successful when high viscosity fluid was injected.

Numerical simulation of heavy fuel oil atomization using a pulsed pressure-swirl injector

It is known that increasing the injection pressure reduces the breakup length and the droplet size.Adding pulses,on the other hand,helps to atomize the liquid into finer droplets,similar to airassisted injectors but without altering the airtofuel concentration.To further reduce the droplet size and breakup length,a novel injector type,called''Pulsed PressureSwirl"(PPS),is introduced in this work,which is a combination of pressureswirl and ultrasonic pulsed injectors.A pressureswirl atomizer was designed and fabricated specifically for Mazut HFO(Heavy Fuel Oil).The droplet formation process and droplet size distribution have been studied experimentally(by shadowgraphy high speed imaging)and numerically(with the opensource VolumeofFluid code Gerris).Changing liquid injection pressure effect on the spray angle and film thickness has been quantified.These simulations have been used to study the primary breakup process and quantify the droplet size distributions,using different injection pulse frequencies and pressures.The numerical results have revealed that the new injector concept successfully produces finer droplets and results in a decrease in the breakup length,especially when applying high pulse frequencies,with no significant changes in the spray angle.

Floating Clamping Mechanism of PT Fuel Injector and Its Dynamic Characteristics Analysis

PT fuel injector is one of the most important parts of modern diesel engine.To satisfy the requirements of the rapid and accurate test of PT fuel injector,the self-adaptive floating clamping mechanism was developed and used in the relevant bench.Its dynamic characteristics directly influence the test efficiency and accuracy.However,due to its special structure and complex oil pressure signal,related documents for evaluating dynamic characteristics of this mechanism are lack and some dynamic characteristics of this mechanism can＇t be extracted and recognized effectively by traditional methods.Aiming at the problem above-mentioned,a new method based on Hilbert-Huang transform（HHT） is presented.Firstly,combining with the actual working process,the dynamic liquid pressure signal of the mechanism is acquired.By analyzing the pressure fluctuation during the whole working process in time domain,oil leakage and hydraulic shock in the clamping chamber are discovered.Secondly,owing to the nonlinearity and nonstationarity of pressure signal,empirical mode decomposition is used,and the signal is decomposed and reconstructed into forced vibration,free vibration and noise.By analyzing forced vibration in the time domain,machining error and installation error of cam are revealed.Finally,free vibration component is analyzed in time-frequency domain with HHT,the traits of free vibration in the time-frequency domain are revealed.Compared with traditional methods,Hilbert spectrum has higher time-frequency resolutions and higher credibility.The improved mechanism based on the above analyses can guarantee the test accuracy of injector injection.This new method based on the analyses of the pressure signal and combined with HHT can provide scientific basis for evaluation,design improvement of the mechanism,and give references for dynamic characteristics analysis of the hydraulic system in the interrelated fields.

Effect of pulsed laser process parameters on welding quality of automobile fuel injector

In this research, pulverization plate and base of a fuel injector in an automobile electronic-controlled engine was joined by pulsed laser welding. The different welding parameters were evaluated and effect of process parameters on joint characteristics was analyzed. The optimal process parameters were obtained as follows： welding current 120 A, welding speed 600 ram/rain, pulse duration 1.80 ms and pulse frequency 60 Hz. The microstructure of weld metal was investigated. Results show that the fusion zone is austenitic dendrite, the weld center is equiaxed grain, while the transition zone between fusion zone and weld center is mixed crystal with austenitic dendrite and equiaxed grain. The weld layered phenomenon was observed, and eddy caused by keyhole effect is the main reason for the formation of layered structure in molten pool.

Elimination of Fuel Pressure Fluctuation and Multi-injection Fuel Mass Deviation of High Pressure Common-rail Fuel Injection System

The influence of fuel pressure fluctuation on multi-injection fuel mass deviation has been studied a lot,but the fuel pressure fluctuation at injector inlet is still not eliminated efficiently.In this paper,a new type of hydraulic filter consisting of a damping hole and a chamber is developed for elimination of fuel pressure fluctuation and multi-injection fuel mass deviation.Linear model of the improved high pressure common-rail system（HPCRS）including injector,the pipe connecting common-rail with injector and the hydraulic filter is built.Fuel pressure fluctuation at injector inlet,on which frequency domain analysis is conducted through fast Fourier transformation,is acquired at different target pressure and different damping hole diameter experimentally.The linear model is validated and can predict the natural frequencies of the system.Influence of damping hole diameter on fuel pressure fluctuation is analyzed qualitatively based on the linear model,and it can be inferred that an optimal diameter of the damping hole for elimination of fuel pressure fluctuation exists.Fuel pressure fluctuation and fuel mass deviation under different damping hole diameters are measured experimentally,and it is testified that the amplitude of both fuel pressure fluctuation and fuel mass deviation decreases first and then increases with the increasing of damping hole diameter.The amplitude of main injection fuel mass deviation can be reduced by 73%at most under pilot-main injection mode,and the amplitude of post injection fuel mass deviation can be reduced by 92%at most under main-post injection mode.Fuel mass of a single injection increases with the increasing of the damping hole diameter.The hydraulic filter proposed by this research can be potentially used to eliminate fuel pressure fluctuation at injector inlet and improve the stability of HPCRS fuel injection.

Fault Detection of Fuel Injectors Based on One-Class Classifiers

Fuel injectors are considered as an important component of combustion engines. Operational weakness can possibly lead to the complete machine malfunction, decreasing reliability and leading to loss of production. To overcome these circumstances, various condition monitoring techniques can be applied. The application of acoustic signals is common in the field of fault diagnosis of rotating machinery. Advanced signal processing is utilized for the construction of features that are specialized in detecting fuel injector faults. A performance comparison between novelty detection algorithms in the form of one-class classifiers is presented. The one-class classifiers that were tested included One-Class Support Vector Machine (OCSVM) and One-Class Self Organizing Map (OCSOM). The acoustic signals of fuel injectors in different operational conditions were processed for feature extraction. Features from all the signals were used as input to the one-class classifiers. The one-class classifiers were trained only with healthy fuel injector conditions and compared with new experimental data which belonged to different operational conditions that were not included in the training set so as to contribute to generalization. The results present the effectiveness of one-class classifiers for detecting faults in fuel injectors.

Failure in Fuel Injector Nozzles Used in Diesel Engines

This paper aims to conduct a study of the problems associated with the wear of the needles and fuel injection nozzles utilized in diesel engines. The wear found on the needles is mainly associated to impurities in the fuel oil and microcavitation occurred due to high pressure in the phase of the air compression for combustion of the combustible fluid. These pressures associated with the temperature and the fluid velocity results in the occurrence of vaporization, which releases shock waves that cause damage to the affected surface. The impurities solid particles from the fuel oil cause problems inside the nozzles as obstruction of the holes and wear on the needle tip and nozzle seat surface. These failures affect in the atomization of the fuel, since the deterioration of the internal passages of the nozzles interferes in the spray formation and in the end passage of the fluid. For the execution of this study it will be used digital microscopic analysis in specimens that suffered damage, in order to investigate the effects of fuel property, and the temperature conditions and pressure in the formation of the wear on the needles and injector nozzle.

The Possibility of Active Attitude Control for Fuel Spray

The internal combustion engine (ICE) is an attractive power source for automobiles, with its superior storability, transportability, and suppliability of liquid fuel with high energy density. Compact ICEs with high performance and a low environmental load are greatly needed. In the future, smart active control of combustion by means of fuel spray injection must be considered as a breakthrough technology to address serious issues related to conventional ICEs, such as emissions. A designed fuel injection rate and spray pattern during the injection period have been technically developed, and combustion can be partially controlled in the conventional ICE. However, spatial fuel distribution is not progressing as desired in the field of combustion;thus, new and effective active control technologies for fuel spray are very necessary for the smart control of combustion. Cavitation, flash boiling, spray-to-spray interaction, spray-to-wall interaction, and air flow have potential as a basis for active attitude control of fuel spray. This article uses evidence from the literature to discuss the possibility of active spray attitude control for future fuel spray combustion technology in a smart compact ICE.

Effects of Blending Long-Chain Alcohols with Jet Fuel on the Macroscopic Spray Characteristics

Long-chain alcohols were considered to be promising alternative fuels and fuel additives. This study was aimed at figuring out the influences of blending long-chain alcohols with jet fuel on the macroscopic spray characteristic. n-Butanol and n-pentanol were chosen as tested alternative fuels. A common-rail injection system was used to create high-pressure injection conditions. The Schlieren imaging system was used to capture spray processes. Results showed that with the addition of long-chain alcohols, the spray tip penetration and the peak spray tip velocity increased, whereas the spray cone angle and the spray area decreased. Comparisons between those macroscopic spray characteristics of AKB blends and AKP blends were also conducted. Compared to AKB blends, AKP blends showed similar spray tip penetration, larger peak tip velocity, smaller spray cone angle, and smaller spray area.

Thermal Modeling of a Novel Heated Tip Injector for Otto Cycle Engines Powered by Ethanol

This work presents a thermal modeling of a new cold-start system technology designed for Otto cycle combustion based on the electromagnetic heating principle. Firstly, the paper presents a state-of-the-art review and presents the context of automobile industry where heated injectors are necessary. The novel method of electromagnetic heating principle to solve the cold-start problem is still in the development phase and it enables engine starting at low temperatures in vehicles powered by ethanol or flex-fuel vehicles (FFV). This new system technology should be available as an alternative to replace the existing system. Currently, the cold-start system uses an auxiliary gasoline tank, which brings some inconvenience for the user. Secondly, the aim was also to create a physical model that takes into consideration all the parameters involved on the heating process such as power heating and average heat transfer coefficient. The study is based on the lumped system theory to model the ethanol heating process. From the analysis, two ordinary differential equations arise, which allowed an analytical solution. Particularly, an ethanol heating curve inside the injector was obtained, an important parameter in the process. Comparison with experimental data from other authors is also provided. Finally, a sensitivity analysis of controlling parameters such as heating power and heat transfer coefficient variation. The paper is concluded with suggestions for further studies.

柴油-天然气双燃料喷射器燃料喷射特性的测试方法

针对双燃料喷射器结构复杂而无法实现喷射特性同时测量的问题,以同心双轴针式喷射器为研究对象,提出一种油和气同场测量方法,用动量法获取喷油规律及喷气规律型线,再通过测试密闭容腔内的压力变化计算喷气量,将二者结合可在测量喷气量的同时测量出精确喷气规律,最后对柴油-天然气双燃料喷射器的常用工况进行测试及验证。结果表明,采用动量法结合容积法的喷气规律测量方法得出的喷气量误差不超过5%。对喷射器的一致性进行验证,喷油量与喷气量的波动率均不超过3%,证明其喷射器一致性较好,该测试技术具有较高的准确度与可信度。

基于三维建模的喷油器流量系数在线测试

该文提出一种柴油机喷油器喷嘴流量系数在线测量方法。通过实验探究了燃油系统内部压力波的演化及传递过程并基于实验数据验证了算法的准确性;基于黎曼不变量理论将燃油系统内部复杂的压力变化过程简化为黎曼波的演化及传递过程,并建立了喷油过程中喷油器入口压力与流量系数的数学关系;根据燃油系统结构提出了一种基于喷油器入口压力信号的黎曼波解耦方法,提高了算法的使用范围。该文搭建了流量系数测量平台,通过实验验证了所提出方法有较高精度。

基于堆叠稀疏自编码器的多缸喷油器堵塞定位算法

燃油喷射系统的工作质量直接影响柴油机工作过程及性能,针对多缸机不同喷油器发生堵塞故障且故障程度不一时,传统故障诊断方法难以精准定位故障喷油器的问题,提出一种基于堆叠稀疏自编码器(Stacked Sparse Autoencoder,SSAE)的故障定位算法。通过SSAE提取不同喷油器发生堵塞故障时轨压信号的深层特征,以softmax网络实现故障部件定位。以一维轨压信号为输入,故障喷油器定位为输出,并研究算法超参数对算法精度的影响。研究结果表明,此算法能精准定位发生堵塞故障的喷油器,且精度不受堵塞程度的影响,故障诊断正确率可达96.7%。

基于网格搜索和投票分类模型的喷油器故障诊断研究

为了提高高压共轨试验台对喷油器检修效率,提出一种基于网格搜索和投票分类模型的喷油器故障自动诊断方法。由于压电喷油器故障数据采集困难,使用AMESim软件模拟不同轨压和脉宽状态下压电喷油器可能出现的多种故障情况。随后,将采集到的1 760组数据使用由随机森林、支持向量机和GBM组成的投票分类模型进行训练,并使用网格搜索法优化各分类器的超参数。实验结果表明:该模型对压电喷油器的5种故障状态及正常状态诊断时的准确率、精确率、召回率和F1-score分别为98.86%、99.13%、98.56%、98.83%,表现出较高的准确性和稳定性。该方法能够快速高效地对喷油器故障情况进行定位。

迈腾B8高压喷油器常见故障诊断

迈腾B8不仅在中国中级车辆的销售市场占有率较高,还是全国汽车技术技能竞赛的主选车型之一。在各类汽车故障中,高压喷油器是故障高发区域之一,对于高压喷油器常见故障及时进行精准诊断,是把握故障原因,做好有效处理的关键。本文主要结合燃油控制电路,对迈腾B8发动机喷油器的喷油过程进行分析,最后以案例的形式,讲解其高压喷油器常见故障的分析诊断过程,最后对于高压喷油器的故障诊断提供几点有效方法参考。通过理论联系案例分析,为更好的把握迈腾B8高压喷油器故障问题提供指导,为高压喷油器的故障诊断和处理提供一些思路和借鉴。

基于PISO算法的汽车喷油器优化仿真研究

通过三维数值模拟软件Converge结合PISO算法,针对重型直喷柴油机,研究喷油器的不同孔径、孔深和喷油倾角对发动机燃烧和排放性能的影响,得到柴油发动机最佳热效率的喷油器参数设置方案。结果表明:相较于喷孔深度和喷孔倾角,喷孔直径的改变对发动机热效率的影响更大,且可有效改善发动机的NO_(x)和碳烟排放。当喷孔直径为0.179 mm、0.219 mm及0.259 mm时,分别能实现1.4%、3.4%、和2.8%的增幅,热效率提升较为显著。

回油背压对高压共轨喷油器喷油特性影响的研究

高压共轨喷油器是柴油机高压共轨电控系统中最重要的一个部件,其喷油特性(如喷油器量)的优劣将直接影响发动机的性能表现。喷油器的喷射特性不仅受到喷油器的结构参数的影响,同时在喷射过程中还受到外界工作环境的影响,比如喷油器喷射时发动机缸内的背压,以及喷油器工作时的回油通道中的背压。本文主要对某高压共轨喷油器进行台架试验测试,研究喷油器回油背压对喷油特性的影响,并分析产生影响的原因,为开发新型的燃油喷射系统提供试验数据。

某船用发电辅机性能优化

为降低某船用发电辅机常用工况油耗,采用仿真分析确定最佳配气相位、压缩比、柱塞速度;通过负荷特性试验及正交试验,确定最佳喷油器方案;通过热怠速试验选择合适的机油泵、海水泵;通过台架负荷特性试验对比发电辅机优化前、后的油耗。结果表明:该发电辅机优化后,进气关闭角对应的曲轴转角为565°,排气开启角对应的曲轴转角为135°,压缩比为15.5,最高柱塞速度提高至2.54 m/s,选用喷孔直径为0.32 mm、喷孔锥角为158°的喷油器,机油泵、海水泵体积流量分别降低10、15 m^(3)/h,辅机常用工况区油耗比原机下降4~5 g/(kW·h),达到降低油耗的目的。

两种不同大小喷孔直径喷油器对柴油机组经济性的影响

柴油机喷油器喷孔直径影响喷油器的雾化特性,而喷油器的雾化特性对柴油机热效率、燃油消耗率、有害物排放、机械故障等有着重要的影响。以某电控单体泵柴油机组为例,分别使用喷孔直径为0.28 mm和0.30 mm的2种喷油器进行负荷试验,对比2种喷油器柴油机组的燃油缸内爆发压力、燃油喷射压力、涡前排温及燃油消耗率。结果表明:使用喷孔直径为0.28 mm喷油器的柴油机组,其经济性优于使用喷孔直径为0.30 mm喷油器的柴油机组。

喷油器安装角对156FMI发动机缸内直喷燃烧过程的影响

以156FMI摩托车发动机为原型,针对其进气道喷射改为缸内直喷时喷油点位置的确定问题展开研究,考察喷油器安装角对缸内直喷燃烧过程的影响。基于四方程湍流模型、Enable扩散模型、walljet碰壁模型、Dukowicz蒸发模型和KHR破碎模型以及ECFM燃烧模型模拟156FMI摩托车发动机缸内直喷燃烧过程,并充分考虑此发动机缸盖空间位置的限制,将喷油器安装在相对气缸盖原火花塞对称位置,研究喷油器安装角对缸内平均压力、温度、瞬时放热率及压力升高率等的影响。结果表明:循环喷油量10 mg、转速3 600 r/min及当量比为1的工况下,θ为55°时,相较于35°峰值压力增大了19.85%,峰值相位提前了2.5°CA,温度峰值升高了14.89%。θ从40°增大到55°时气缸内的压力、温度、瞬时放热率和累积放热量峰值都不同程度地出现了上升,峰值对应的相位角也出现了不同程度的提前,缩短了着火落后期,使气缸内的混合气燃烧速率加快。当θ为55°时,火焰传播速率最快,气缸内的热功转换效率最高,其在燃烧性能方面较好。研究结果为156FMI摩托车发动机缸内直喷技术的应用提供了理论指导和参考。