小型轴针式低惯量喷油器配机燃烧过程的研究

本文介绍国内最新开发的、装有小型P 系列轴针式喷油嘴的低惯量喷油器的喷油过程和配机燃烧过程的主要特点,从热力学上解释了小型轴针式低惯量喷油器改善小型分隔室式柴油机性能的原因。这种小型喷油器由于具有显著的节能效果可望具有广阔的应用前景。     

低惯量喷油器对直喷式柴油机性能影响的研究

喷油器运动件惯量,是影响柴油机性能的重要因素之一。在高速柴油机中,低惯量喷油器有高速响应灵敏、针阀起落迅速、断油干脆等优点,从而提高了喷嘴对高速化的适应性,有助于柴油机性能的改善, 不过通过试验发现,低惯量喷油器在柴油机的全部工作范围内,对柴油机性能影响情况很不一致。它随柴油机工况变化、负荷变化而异。此外,对不同的燃烧室,其影响程度也不相同。本文通过油泵试验台上低惯量喷油器与传统式喷油器喷油规律的对比,以及两种进气道、两种燃烧室的单缸柴油机试验结果及实机测录的动态压力的对比分析,探索其匹配规律。     

启喷压力对直喷式柴油机燃烧的影响

作者介绍了启喷压力对采用低惯量喷油器的直喷式柴油机性能影响的研究结果。通过采用激光全息和高速摄影等技术对燃油喷雾与气缸内燃烧过程的观察与分析，揭示启喷压力与燃油喷雾，混合气形成，扩散燃烧间的重要关系。根据研究结果，提出了直喷式柴油机采用低惯量喷油器启喷压力的一般方法。     

P系列轴针式喷油嘴及其低惯量喷油器的研制

一种国内最小型的P 系列轴针式喷油嘴及其低惯量喷油器已研制成功。它具有外形尺寸小、质量轻、运动件惯量低、高压容积小、配机性能好等特点。可适用于缸径D=60～100mm 的分开式燃烧室柴油机。     

P系列油嘴的加工工艺及设备的引进

1 前言 随着柴油机向着高速、直喷、低惯量等方向的发展,对柴油机的心脏——油泵油嘴提出了更加苛刻的要求。近年来,为适应小缸径柴油机直喷化的发展需要,小尺寸低惯量的P系列油嘴及喷油器总成引起行业的重视,得到蓬勃的发展。国内各大油泵油嘴厂均花费大量人力、物力、财力,争先试制P系列油     

喷油器定位销断裂故障排除及预防

<正> 英国CAV公司生产的低惯量喷油器,其工作性能是优越的。我国一拖生产的100等系列柴油机也采用了类似的低惯量喷油器,而且这种喷油器有逐步推广的趋势。但是笔者在使用拆装过程中,感到这种喷油器在结构上存在着明显的不足,在拧紧喷油头紧帽时,稍不留神就会将针阀体上的两根定位销扭切断。从结构上看,针阀体的定位孔直径为φ2.1mm,而喷油器体的定位销直径仅有φ1.6mm,虽然孔销之间的间隙在理论上是(1.6～2.1)/2mm,应能使断裂后的销头自动掉出来。但实际上却由于定位销断裂时发生扭曲、膨胀,使得定位销在被切断时突然卡死并粘连在定位孔内。如果不取出断销,喷油头就无法使用;若靠硬性敲打,弄不好则会因小(销)失大,造成喷油器报废。要将断销从针阀体中取出,可采用如下方法:先把喷油头固定好,用尖冲把定位销向下冲实,露     

喷油系统对直喷式柴油机性能影响的研究

大量试验和计算分析证实了喷油器结构因素对直喷式柴油机工作性能有很大的影响，本文以系统试验为基础，探讨总结了喷油系几个主要结构参数的影响。重点讨论喷孔直径和喷油器惯量（调压弹簧和挺杆的重量）以及喷油器安装高度的影响，这具有较大的实用性和对性能改进的参考价值。     

喷油系统对直喷式柴油机性能影响的研究

大量试验和计算分析证实了喷油器结构因素对直喷式柴油机工作性能有很大的影响，本文以系统试验为基础，探讨总结了喷油系几个主要结构参数的影响。重点讨论喷孔直径和喷油器惯量（调压弹簧和挺杆的重量）以及喷油器安装高度的影响，这具有较大的实用性和对性能改进的参考价值。     

新型船用气(汽)泡雾化喷油器的燃烧性能试验研究

通过在燃烧柴油的船用锅炉上对气泡雾化喷油器的燃烧试验,并与机械雾化离心式喷油器对比,结果表明:使用气泡雾化喷油器可以使燃油燃烧更加充分,减少冒黑烟现象;同样工况下,气泡雾化喷油器所需油压较机械雾化离心式喷油器低;同样风压下,气泡雾化喷油器燃烧效率更高;采用蒸汽为雾化介质时,炉膛温度提高的同时排烟温度较大降低。     

喷油嘴开启压力对柴油机低速性能影响的研究

本文介绍喷油嘴开启压力对柴油机低速大负荷时性能影响的研究。试验工作是在一台具有直喷式燃烧系统和低惯量喷油器的单缸柴油机上进行的。结果表明,过高的喷油嘴开启压力不仅会恶化柴油机的比油耗与烟度等性能指标,而且会降低其在低速大负荷时的工作稳定性。通过对嘴端燃油压力波的观察分析发现,造成这一现象的原因在于柴油机供油系统的供油速率不足,增大供油速率则可以改善上述情况。本研究结果为合理选择在喷式柴油机的喷油嘴开启压力提供一个参考。     

超音速燃烧的喷嘴模型研究

在综合现有的强化混合技术基础上，提出了一种新的喷嘴模型－低角度分级喷嘴模型，并设计了缩尺寸燃烧室。通过燃烧室入口马赫数为２的氢燃烧超音速燃烧实验，获得了超音速燃烧室中壁压沿轴向的变化规律，证明了低角度分级喷嘴模型燃烧室比目前公认的后掠斜坡喷嘴模型燃烧室有更高的燃烧效率。     

P系列双弹簧喷油器与CA498柴油机的匹配研究

在一台498增压中冷柴油机上对开发的P系列双弹簧喷油器与普通P系列单弹簧喷油器进行了性能、排放、噪声及低速稳定性等一系列匹配试验研究,结果表明：使用P系列双弹簧喷油器能在保持柴油机动力性、经济性原有较好水平的前提下,明显地改善低速稳定性、NOx排放以及降低柴油机噪声(燃烧噪声)。     

Fuel injector deposits in direct-injection spark-ignition engines

Controlling fuel injector deposits is recognized as a challenge for advanced direct-injection spark-ignition (DISI) engines. This paper gives a comprehensive overview of the research on formation, measurement, effect, and mitigation of injector deposits in DISI engines. Methodologies for the injector deposit studies include visual and compositional analysis. It is shown that injector deposits will reduce injector fuel flow rates, and lead to changes in spray characteristics. Consequently, spray angle and envelope are likely to be affected, and spray penetration distance as well as droplet diameter can be increased. Injector deposits are revealed to be primarily fuel-derived and created by two distinct free radical pathways, i.e., low temperature auto-oxidation and high temperature pyrolysis. Fuel compositions (olefins, aromatics, and sulphur), as well as T90 parameter, are significant factors in injector deposit formation. The worst consequences of injector fouling are pre-ignition, and engine misfiring and malfunction. Emissions, especially particulates, dramatically increase as the fuel injector becomes fouled. It appears that fuel detergent is the most effective method in controlling injector deposit formation if its chemistry and dosage rate are optimized. Outward opening piezo-driven injector configuration with a good surface finish, a sharp nozzle inlet, and a counter bore design, is useful in preventing injector deposit formation. Reducing injector nozzle temperature by methods such as designing special injector cooling passages, and improving engine design are also proven to be helpful in reducing injector fouling. Anti-deposit coatings only delay the onset of injector deposit formation.     

Experimental Investigations of Micro Air Injection to Control Rotating Stall

Steady discrete micro air injection at the tip region in front of the first compressor rotor has been proved to be aneffective method to delay the inception of rotating stall in a low speed axial compressor.Considering the practicalapplication a new type of micro injector was designed and described in this paper,which was imbedded in thecasing and could be moved along the chord.In order to verify its feasibility to other cases,such as high subsonicaxial compressor or centrifugal compressor,some other cases have been studied.Experimental results of the samelow speed axial compressor showed that the new injector could possess many other advantages besides success-fully stabilizing the compressor.Experiments performed on a high subsonic axial compressor confirmed the ef-fectiveness of micro air injection when the relative velocity at the blade tip is high subsonic.Meanwhile in orderto explore its feasibility in centrifugal compressor,a similar micro injector was designed and tested on a lowspeed centrifugal compressor with vaned diffuser.The injected mass flow was a bit larger than that used in axialcompressors and the results showed micro injection could also delay the onset of rotating stall in the centrifugalcompressor.     

冷启动时PTC-base喷油器内高压瞬变流场传热研究

汽车在冷启动时有害物质排放很高,这和燃油温度有很大关系。本研究提出一种基于PTC的喷油器,该喷油器是在普通喷油器内部油路周围嵌入PTC材料,并以车载电源供电。当温度低于居里温度时,PTC材料的电阻很小,因此可产生大量热量,这些热量可以使流经管路的燃油得到加热。当温度达到居里温度时,PTC材料电阻变得很大,材料停止发热。利用PTC材料的这种特殊的阻温特性,我们可以在车辆启动时把喷油器出口的燃油温度控制在一个理想的范围。本研究的主要工作是对PTC-base喷油器建立模型并对不同条件下该喷油器的燃油传热进行分析。分析结果表明,冷启动时,在PTC-base喷油器中,燃油可以得到很好的加热。这对降低汽车冷启动排放将产生重要的作用。     

Investigation of the effect of pilot burner on lean blow out performance of a staged injector

The staged injector has exhibited great potential to achieve low emissions and is becoming the preferable choice of many civil airplanes. Moreover, it is promising to employ this injector design in military engine, which requires most of the combustion air enters the combustor through injector to reduce smoke emission. However, lean staged injector is prone to combustion instability and extinction in low load operation, so techniques for broadening its stable operation ranges are crucial for its application in real engine.
In this work, the LBO performance of a staged injector is assessed and analyzed on a single sector test section.The experiment was done in atmospheric environment with optical access. Kerosene-PLIF technique was used to visualize the spray distribution and common camera was used to record the flame patterns. Emphasis is put on the influence of pilot burner on LBO performance. The fuel to air ratios at LBO of six injectors with different pilot swirler vane angle were evaluated and the obtained LBO data was converted into data at idle condition. Results show that the increase of pilot swirler vane angle could promote the air assisted atomization, which in turn improves the LBO performance slightly. Flame patterns typical in the process of LBO are analyzed and attempts are made to find out the main factors which govern the extinction process with the assistance of spray distribution and numerical flow field results. It can be learned that the flame patterns are mainly influenced by structure of the flow field just behind the pilot burner when the fuel mass flow rate is high; with the reduction of fuel, atomization quality become more and more important and is the main contributing factor of LBO. In the end of the paper,conclusions are drawn and suggestions are made for the optimization of the present staged injector.     

Stabilization regimes and pollutant emissions from a dual fuel CH4/H2 and dual swirl low NOx burner

Burning hydrogen in gas turbines is a relevant technological solution to decarbonize power production and propulsion systems. However, ensuring low NOx emission and preventing flashback can be challenging with hydrogen. Stabilization regimes and pollutant emissions from partially premixed CH₄/H₂/air flames above a coaxial Dual Fuel Dual Swirl injector are investigated in a laboratory-scale combustor at atmospheric conditions for increasing hydrogen contents. The injector consists of an external annular swirler providing premixed methane/air and a central channel fed with pure hydrogen. This burner virtually removes the risk of flashback due to the late injection of hydrogen. Flame stabilization regimes, CO and NOx emissions are analyzed for different configurations of the injector and operating points. The effect of swirling the hydrogen stream is investigated together with the influence of the hydrogen injector recess, i.e. its nozzle position with respect to the backplane of the combustion chamber. It is shown that swirling the central hydrogen stream favors aerodynamically stabilized flames resulting in a low thermal stress on the injector and limited NOx emissions. The study also highlights that a small recess of the central hydrogen injector widely extends the operability range of the burner with aerodynamically stabilized flames. With a sufficient inner swirl and a small recess, flames detach from the injector rim when the hydrogen bulk velocity is large enough. In this configuration, it is found that NOx emissions remain low even for operation with pure hydrogen. Moreover, NOx emissions decrease when increasing the thermal power for a fixed equivalence ratio.     

伞状喷雾及HL喷雾在柴油机均质预混合燃烧中的应用研究

针对柴油机均质预混合燃烧的混合气形成提出满足喷雾碰壁少，雾化好等要求的早期喷射缸内预混合方式，并对喷雾状态、性质及其预混合燃烧做了深入探讨。对HL喷雾与多孔喷雾做了比较研究。试验证明，HL喷雾具备双工作模式的能力。     

喷油嘴密封座面对共轨喷油器开启压力散差的影响

解释了机械式喷油器与电控共轨喷油器在开启压力的控制方式上的不同,阐述了电控共轨喷油器在开启时针阀的受力状态,试验验证了喷油嘴密封座面的散差会影响喷油器开启压力的散差,在装配前对喷油嘴的密封座面进行检测、分组,就能够明显降低其对喷油器开启压力散差的影响.     

喷油器电磁阀电流反馈驱动控制研究

采用Simulink建立了喷油器电磁阀的数学模型,根据电流反馈控制思路开展喷油器驱动控制技术研究。设计了电流反馈控制型高低压分时驱动电路,并采用Multisim软件对该驱动电路进行仿真。仿真结果表明:该电路可通过峰值电流、维持电流反馈回路自动控制驱动电流的大小。针对某型喷油器进行了驱动试验,结果表明:喷油器电磁阀模型准确,电流反馈控制驱动电路性能优良。