柴油机主辅双进气道系统性能优化研究

对大功率柴油机采用主辅双进气道系统改善低负荷工况下的进气涡流进行理论分析和试验研究,并对进气控制挡板参数进行了优化。研究结果表明：在低负荷工况下,以螺旋气道进气为主,直流气道进气为辅,可以获得较强的进气涡流,达到改善低负荷性能的目的。     

TBD620柴油机进气系统性能研究

对TBD620柴油机进气系统进行了理论和试验研究。缸头气道稳流试验数据表明该机在低负荷工况下,在进气量较小时,采用单独涡流气道进气和直流气道不完全封闭,可以获得较大的进气涡流,达到改善大功率柴油机低负荷性能的目的。     

TBD620柴油机瞬态进气过程的三维数值仿真

利用PRO/E建立TBD620柴油机的进气道和燃烧室三维模型,采用FIRE软件对进气过程进行仿真计算,分析了TBD620柴油机双进气道可控涡流系统对瞬态进气过程中涡团发展的影响。结果表明,双进气道可控涡流系统产生的进气涡流能显著改善缸内混合气的形成,提高柴油机低负荷工况时的燃烧性能。     

船用直喷式柴油机的可控进气涡流技术

通过对直喷式柴油机进气系统的理论分析和试验研究表明,双进气道的设计目的是达到较高的流通能力和适度的进气涡流,而阀板控制着进气涡流的强度,兼顾在高低转速下进气涡流和燃油喷雾的最佳化调整, 起到了控制排放和降低油耗的作用。可控进气涡流系统可综合改善柴油机高、低负荷性能,在实际使用时还应考虑在系统上的配置。才能减少氮氧化物排放和降低燃烧噪声。     

TBD620柴油机缸内工作过程仿真研究

利用PRO／E建立TBD620柴油机的进气道和燃烧室三维模型;并在FIRE软件中对进气、压缩和燃烧过程进行仿真计算。分析了TBD620柴油机双进气道可控涡流系统对缸内涡流、油气混合和燃烧排放特性的影响。结果表明,低负荷工况时关闭双进气道可控涡流系统的进气控制阀能显著改善缸内混合气的形成,提高柴油机燃烧及排放性能。     

双进气道柴油机可调进气涡流形成机理的研究

在稳流气道试验台上,分别对两种由直气道和螺旋气道组合的双进气道柴油机的进气涡流调节特性进行了试验,结果显示:两种组合方式下的双进气道的可调进气涡流特性存在很大差异.利用三维进气流动仿真技术,对两种气道组合的双进气道进气涡流调节特性分别进行了仿真计算,计算所得的涡流比和流量系数与试验结果具有较好的一致性.通过对两种组合方式下进气涡流调节前后的流场变化及差异作进一步的分析比较,得到了双进气道柴油机可调进气涡流形成的机理.     

TBD620柴油机低负荷性能研究

对采用双进气道可控涡流系统的TBD620柴油机进行了理论分析，工作过程计算和实机试验，结果表明其低负荷工况性能较好满足经济性，烟度等要求。     

四气门柴油机的可变涡流进气系统的试验研究

设计开发了四气门柴油机单独进气道及四气门柴油机试验缸盖,分析了四种组合气道方案下关闭一个进气道对四气门柴油机进气道性能的影响。从而探求四气门柴油机的可变进气涡流系统的实现方法,在低速时通过关闭一个气道,可以形成四气门柴油机的可变进气涡流系统,具体关闭哪个气道取决于气道的不同组合。     

进气道位置对柴油机进气涡流可调性能影响的试验研究

针对某型号四气门柴油机设计制作了一个螺旋气道和直气道的阴模试验件,在稳流气道试验台上,利用挡板部分遮挡直气道的入口,实现进气涡流的调节,进行了进气道位置对进气涡流及其可调性能影响的试验,试验结果表明：两个进气道的位置不同,对进气流量的影响很小,但是对涡流比以及涡流比的调节范围有较大影响.     

四气门柴油机进气道组合对涡流和流量影响的研究

四气门柴油机进行气道可以选用不同类型的进气道进行组合,如二个螺旋进气道、二个切向进气道或一个切向进气道一个螺旋进气道等。螺旋进气道和切向进气道气门出口处气流分布不同,不同的气道组合对进气涡流影响必然不同。本文介绍了在气道稳流试验台上进行试验研究的结果。     

可变涡流进气系统及其在直喷式汽油机中的应用

设计了一种简单的阀片式变涡流控制系统。在螺旋气道中安装一适当形状的阀片,可在较大范围内连续调节涡流比。在充气效率不受影响的情况下,本涡流控制系统可使涡流比在０．３５～１．６８之间变化。通过在稳流吹风试验台上的大量试验,对阀片形状,包括阀片外形和逆流弯角进行了优化。将本系统应用在汽油机直接喷射分层燃烧系统中,发动机的综合性能,尤其是低负荷下的排放性能有了较大的改善。试验表明,当涡流比在１．０～１．５之间变化时,所研究的直接喷式汽油机在低负荷工况下ＣＯ、ＨＣ和ＮＯｘ的排放水平较低。     

A study on the effects of the intake port configurations on the swirl flow generated in a small D.I. diesel engine

This paper investigates the effect of intake port configuration on the swirl that is generated within a direct injec- tion （D.I.） diesel engine. The in-cylinder flow characteristics are known to have significant effects on fuel-air mixing, combustion, and emissions. To clarify how to intensify the swirl flow, a swirl control valve （SCV） and a bypass were selected as design parameters for enhancing the swirl flow. The optimal intake port shape was also chosen as a parameter needed to efficiently generate a high swirl ratio. The results revealed that a key factor in generating a high swirl ratio was to control the intake airflow direction passing through the intake valve seat. Further, the swirl intensity was influenced by changing the distance between the helical and tangential ports, and the swirl flow was changed by the presence of a bypass near the intake valve seat. Additionally, the effect of in- take port geometry on the in-cylinder flow field was investigated by using a laser sheet visualization method. The experimental results showed a correlation of swirl ratio and mass flow rate. In addition, we found that employing the bypass was an effective method to increase swirl ratio without sacrificing mass flow rate.     

基于Kiva3v的柴油机进气和压缩过程模拟

借助专业的网格划分软件,生成带有螺旋进气道的柴油机分块结构化六面体计算网格,基于ki-va3v程序,建立了柴油机的进气压缩仿真模型。计算发动机倒拖的缸内压力,外特性工况点的进气量,并与试验值进行了对比,结果显示吻合较好。分析了缸内的滚流比与涡流比以及缸内的流场变化。缸内涡流比的变化过程对发动机转速的变化不敏感,在压缩上止点达到了最大值。缸内的气流流场在进气压缩过程中变化复杂,产生的涡旋经历了生成、发展和衰减的演变过程。在压缩过程中,缸内的湍流强度在燃烧室区域最强。     

Combustion and emissions control in diesel–methane dual fuel engines: The effects of methane supply method combined with variable in-cylinder charge bulk motion

In this paper, the results of an extensive experimental campaign about dual fuel combustion development and the related pollutant emissions are reported, paying particular attention to the effect of both the in-cylinder charge bulk motion and methane supply method.A diesel common rail research engine was converted to operate in dual fuel mode and, by activating/deactivating the two different inlet valves of the engine (i.e. swirl and tumble), three different bulk flow structures of the charge were induced inside the cylinder. A methane port injection method was proposed, in which the gaseous fuel was injected into the inlet duct very close to the intake valves, in order to obtain a stratified-like air–fuel mixture up to the end of the compression stroke. For comparison purposes, a homogeneous-like air–fuel mixture was obtained injecting methane more upstream the intake line. Combining the different positions of the methane injector and the three possible bulk flow structures, seven different engine inlet setup were tested. In this way, it was possible to evaluate the effects on dual fuel combustion due to the interaction between methane injector position and charge bulk motion. In addition, methane injection pressure and diesel pilot injection parameters were varied setting the engine at two operating conditions.For some interesting low load tests, the combustion development was studied more in detail by means of direct observation of the process, using an in-cylinder endoscope and a digital CCD camera. Each combustion image was post-processed by a dedicated software, in order to extract only those portions with flame presence and to calculate an average luminance value over the whole frame. These luminance values, chosen as indicators of the combustion intensity, were represented over crank angle position and, then, an analysis of the resulting curves was performed.Results showed that the charge bulk motion associated to the swirl port, improving the charge mixing of the diesel spray and the propagation of the turbulent flame fronts, is capable to enhance the oxidation of air–methane mixture, both at low and high engine loads. Furthermore, at low loads, the analysis of combustion images and luminance curves showed that methane port injection can significantly affect the intensity and the spreading of the flame during dual fuel combustion, especially when a suitable in-cylinder bulk motion is obtained.Concerning the engine emissions, some correlations with what observed during the analysis of the combustion development were found. Furthermore, it was revealed that, for several combinations of the engine operating parameters, methane port injection was always associated to the lowest emission levels, demonstrating that this methane supply method is a very effective strategy to reduce unburned hydrocarbons and nitric oxides concentrations, especially when implemented with variable intake geometry systems.     

可变涡流对高速柴油机性能影响的仿真研究

采用计算仿真的方法模拟某高速柴油机缸内的工作过程,分析柴油机缸内及进排气道内的流场、缸内燃烧过程以及有害排放物的生成。计算过程中采用部分或完全关闭一个进气道的方法改变缸内涡流状况,分析不同气道关闭方案下缸内涡流的强度,及其对柴油机动力性、经济性及排放性能的影响。计算结果表明,对柴油机完整工作循环进行三维数值模拟计算可获得缸内瞬态流场参数,当转速低于2400r·min-1时,完全关闭一个进气道可以在对动力性和经济性影响很小的情况下显著提高缸内涡流强度,减少碳烟的峰值生成量;部分关闭一个进气道,可以在对动力性、经济性几乎不影响的情况下减少NOx的生成量。     

进气道和燃烧室形状对大缸径天然气发动机缸内流动和燃烧的影响

为了提升采用当量燃烧的大缸径天然气发动机的指示热效率,提出了组织弱涡流、强滚流、高湍流强度的缸内气流运动的理念,据此设计了不同形状的进气道和燃烧室,并采用三维数值模拟的方法研究了进气道和燃烧室形状对缸内流动和燃烧的影响.研究发现:与原机相比,当将原螺旋进气道改为直进气道并配合原缩口型、新的直口型、敞口型和半球型燃烧室时...     

发动机诱导产生进气涡流和可调进气涡流的研究

在稳流气道试验台上开展了诱导产生发动机进气涡流和可调进气涡流的研究工作,证明在短直气道内,通过安装进气导流片能够产生一定强度的进气涡流,再配合另一气道进气流量的控制,可获得发动机缸内可调的进气涡流。非增压发动机试验表明在低速低负荷工况下,发动机的燃油消耗率有明显的改善。     

缸内涡流比对冷起动燃烧火焰的影响探究

针对汽油发动机冷起动存在的燃烧不稳定、燃烧效率低的问题,基于单缸可视化发动机在冷起动工况下调节进气涡流,通过分析缸内燃烧火焰特性来探究增强进气涡流对发动机循环波动及输出功率的影响。试验所用发动机为单缸四气门(两进两出)缸内直喷汽油机,其中一个进气道加装有涡流控制阀,通过将一个进气道关闭或者开启来改变缸内涡流的强度。利用高速相机从活塞上的光学通道得到发动机缸内的火焰传播图像,并计算火焰传播面积,提取火焰边界,获取火焰中心速度及火焰扩散速度等信息,同时也利用燃烧分析仪对缸内压力、燃烧放热率等特性进行同步测量和记录,通过多角度的对比和分析揭示缸内燃烧状况与发动机宏观性能的相关联系,有效地发掘了在不同涡流强度下缸内火焰的传播特征。研究结果从缸内燃烧火焰的角度解释了提高涡流比能够很好地提高冷起动的燃烧稳定性,促进发动机缸内燃烧。研究表明,早期火核分布越集中,波动越小,后期循环波动就越小。试验结果还表明,由缸压计算的瞬时放热率与火焰面积存在很好的线性关系。