中文摘要: 针对乙醇与汽油固定掺混比例下使用不能充分发挥乙醇燃料优势的问题，开发出了乙醇汽油双燃料-双直喷系统，并在一台点燃式单缸试验机上进行试验，研究了稀薄燃烧下3种不同的喷射策略对发动机燃烧和性能的影响。研究发现：在稀薄燃烧的情况下，随喷射时刻的推迟，不同喷射策略下动力性呈现先增长后降低的趋势。在保证喷油量不变时，有效热效率随过量空气系数增大而明显提高，当量燃油消耗率逐渐降低。随喷射时刻的推迟，热效率呈现先升高后降低的趋势。在过量空气系数为1.2，汽油喷射时刻为上止点前180°，乙醇喷射时刻为上止点前300°时，有效热效率达到最高值40.5%。此外，相比于汽油，添加乙醇燃料使得稀薄燃烧更稳定，循环波动更小。 英文摘要: The advantages of ethanol cannot be fully utilized when ethanol is mixed with gasoline in a fixed proportion. To solve this problem, a system which can inject both ethanol and gasoline directly into cylinder was developed. With this system, the effects of three different injection strategies on combustion characteristics and engine performance under lean-burn condition were experimentally conducted on a spark ignition gasoline engine. The three injection strategies were: injecting gasoline and ethanol at the same time; fixing gasoline injection timing and delaying ethanol injection timing gradually; fixing ethanol injection timing and delaying gasoline injection timing gradually. The results show that with the three injection strategies engine power output and thermal efficiency increase first and then decrease with the delay of the injection timings under lean-burn condition. When the amount of injected fuel is kept constant, the effective thermal efficiency increases remarkably with the excess air coefficient, while the equivalent fuel consumption decreases gradually. The optimal combustion is obtained at the excess air coefficient of 1.2 and with the gasoline injection timing of 180° in crank angle before the top dead center and ethanol injection timing of 300° in crank angle before the top dead center. In this case, the effective thermal efficiency peaks to 40.5%. Besides, adding ethanol into gasoline makes lean-burn combustion more stable with less cycle variation.

中文摘要: 利用直径0.22 mm的单孔喷嘴高压共轨喷油器，以喷油器油量标定数据及控制参数为基础,采用高速相机成像技术在定容燃烧室内在等喷油量变喷油压力的前提下测量了着火点、着火滞燃期、燃烧持续期、火焰面积(AF)和火焰自然发光强度(SINL)的变化规律，对比研究了RP-3航空煤油、柴油碰壁喷雾的着火和燃烧特性。结果表明：在低喷油压力下着火点分布在离壁面较远的区域，在较高喷油压力下着火点位于壁面上，距喷油器中心线的距离随喷油压力的增加而增加，且RP-3航空煤油着火点距喷油器的距离比柴油更远。随着喷油压力的增加，RP-3航空煤油碰壁喷雾火焰的着火滞燃期先降低后增加，柴油碰壁喷雾火焰的着火滞燃期不断降低，且RP-3航空煤油具有更短的着火滞燃期。燃烧持续期随喷油压力的增加而降低，RP-3航空煤油的燃烧持续期比柴油短。喷油压力越高，火焰面积（AF）和自然发光强度（SINL）的变化速率越高，而AF和SINL的最大值及达到最大值所需的时间越小。与柴油相比，RP-3航空煤油的AF、SINL具有更高的变化速率，且AF、SINL的峰值更高，达到峰值的时间更短。 英文摘要: The ignition and combustion characteristics of wall-impinged kerosene(RP-3) and diesel spray were comparatively investigated under the condition of a fixed injection mass and different injection pressures and based on calibrated fuel injection quantity data and corresponding control parameters. Adopting a common rail nozzle with single-hole of 0.22 mm, the experiments were conducted in a constant volume combustion vessel to simulate diesel engine condition. Flame images were captured using a high-speed camera, and then the behaviors of ignition and combustion were processed. The variation laws of ignition position, ignition delay time, combustion duration, flame area(AF) and spatially integrated natural luminosity(SINL) of both wall-impinged fuel sprays were determined by analyzing the flame images. The results show that at low injection pressures, the ignition positions of both fuels are in the region that is far from the wall surface. At high injection pressures, the ignition positions of both sprays are on the wall surface, and are pushed farther away from the injector center-line with the increase of the injection pressures. The ignition positions of the kerosene spray are farther away from the injector center-line than those of the diesel spray. The ignition delay of the wall-impinged kerosene flames shortens first and then prolongs with the increase in the injection pressure, and that of the diesel flames reduces with the increased injection pressure. The kerosene RP-3 spray has a shorter ignition delay than the diesel spray. The combustion durations of both sprays are shortened with the increased injection pressures, but that of the kerosene RP-3 spray is shorter. Increasing the injection pressures enhances the variation rates of AF and SINL of both sprays, but the maximum values of AF and SINL and the time to reach them decreases. The kerosene RP-3 spray has higher variation rates of AF and SINL, greater values of the maximum AF and SINL, and shorter time to reach the maximum AF and SINL compared to the diesel spray.

中文摘要: 运用激光诱导荧光法（LIF）定量分析了缸内直喷汽油机单孔喷油器喷雾撞壁的二维油膜特性。研究发现：燃油在壁面上向油膜铺展的方向聚集，并在边缘形成较厚的油膜。高喷射压力有助于形成质量较小且厚度较薄的油膜，同时减小喷射脉宽能进一步降低燃油附壁率。增加撞壁距离能同时减小油膜质量和油膜面积，然而油膜的平均厚度并未减小，对油膜蒸发并没有明显的促进作用。将喷射角度从15°增加到45°能够显著减少油膜质量和平均厚度。 英文摘要: The two-dimensional oil film characteristics of the single-hole injector spray wall impingements in a direct injection gasoline engine were quantitatively analyzed by the laser induced fluorescence method. Results show that the fuel accumulates on the wall in the direction of oil film expansion and forms a thicker oil film on the edge. High injection pressure helps to form an oil film with a lower mass and a thinner thickness, while reducing the jet pulse width can further reduce the fuel adherence rate. Increasing the wall impingement distance can simultaneously reduce the oil film quality and the oil film area, but can not reduce the average thickness of the oil film, so there is no obvious promotion effect on the oil film evaporation. Increasing the spray angle from 15° to 45° can significantly reduce the oil film quality and average thickness.

中文摘要: 针对一款4缸1.5 L废气涡轮增压缸内直喷汽油（GDI）发动机，进行了废气再循环（EGR）缸内稀释燃烧技术、空气缸内稀释燃烧技术与原机燃烧的经济性、排放特性对比试验研究。研究了不同缸内稀释技术对发动机性能和排放影响的变动规律，并对比分析了相同稀释率下、采用不同稀释技术时发动机的性能变化。结果表明：空气稀释率在49.5%时比油耗相比原机下降6.2%，而EGR稀释率在20.5%时经济性改善4.2%，在相同稀释率时，EGR稀释可采用更为提前的点火角实现更优的燃烧相位，但空气稀释所带来的多变指数提升使其经济性优于EGR稀释，且发动机燃烧系统对空气稀释程度具有更强的容忍性；NOx 排放在空气稀释率为11.0%时达到峰值水平，随后随着稀释率的提高不断下降，而EGR稀释的NOx 排放随着稀释率的提高持续大幅下降；空气稀释的CO排放水平远低于原机，EGR稀释的CO排放随着稀释率的增加而略有下降；对于HC排放，空气稀释的排放量低于EGR稀释，而当空气稀释率由49.5%增加为68.0%时，HC排放出现较大幅度上升。 英文摘要: A comparative test of fuel economy and emission characteristics was carried out on a 1.5 L turbocharged direct injection gasoline engine using different technologies of exhaust gas recirculation(EGR) and in-cylinder air diluted combustion. Results show that compared with the original engine, the use of an air diluted combustion system can reduce fuel consumption by 6.2% at an air dilution rate of 49.5%, while with the EGR system, fuel consumption can be improved by 4.2% at a dilution rate of 20.5%. At the same dilution rate, the EGR system can use a more advanced ignition timing to achieve a better combustion, while the polytrophic exponent increment caused by the air diluted combustion system makes the engine more economical than the EGR system, and the engine is more tolerant to air dilution. When the air dilution rate of the air diluted combustion system is 11%, the engine emissions reach the highest level, and then decrease with the increase of air dilution rate. As for the EGR system, as the dilution rate increases, NOx emissions continue to drop significantly. In addition, when using the air diluted combustion system, CO emissions will be much lower than the original engine, while for the EGR system, CO emissions slightly decrease with the increase of dilution rate. Moreover, the use of air diluted combustion system can make HC emissions lower than the EGR system, and when the air dilution rate increases from 49.5% to 68.0%, HC emissions will increase significantly.

中文摘要: 为了研究轨道压力、主喷正时、预喷正时及预喷油量这4个主要喷油参数对增程式电动汽车增程器（APU）发动机有效燃油消耗率和NOx 排放特性的影响，根据APU发动机不同工况下的运行特点，结合整车功率需求及所匹配发电机的最佳工作区域，采用多工况点模式的基础控制策略，选取3个稳态工况点为APU发动机的运行工况。之后基于空间填充+V最优设计方法采用混合试验方案，利用二阶多项式回归模型+径向基函数（RBF）神经网络模型建立发动机性能和排放拟合模型。给出APU发动机的性能优化约束条件和优化目标，利用法线-边界交集优化算法（NBI）进行油耗最低和NOx 排放最低的双目标优化，确定了3个稳态工况点的最佳喷油策略。结果表明各工况点在优化后的有效燃油消耗率平均降低了4.03%，NOx 排放平均降低了30.51%。 英文摘要: In order to study the effect of rail pressure, main injection timing, pre-injection timing and pre-injected fuel amount on the fuel consumption and NOx emission characteristics of the auxiliary power unit(APU) engine for an electric vehicle, according to the operating characteristics of the APU engine under different operating conditions, together with the vehicle's power demand and optimal operating area of the matched generator, the basic control strategy of multi-mode was adopted, and three steady-state operating points were selected as the operating conditions of the APU engine. Then, based on the space filled+V optimal design method, the hybrid test was adopted, and an engine performance and emission fitting model was established by using the regression calculation and neural network model. Under the given conditions of engine performance optimization conditions and optimization objectives, the normal boundary intersection optimization method was used to optimize the double target with minimum fuel consumption and NOx emissions, and the optimal fuel injection strategy for three steady-state operating points was determined. Results show that compared to the original engine, the optimized fuel consumption of each mode is reduced by 4.03% on average, and the average NOx emissions is reduced by 30.51%.

中文摘要: 为了研究掺烧含氧燃料对柴油机排放及柴油机氧化催化器（DOC）耦合催化型柴油机颗粒捕集器（CDPF）后处理系统低温氧化特性与再生特性的影响，基于一台4缸高压共轨柴油机，选取国五柴油、15%生物柴油-柴油（D85B15）、15%正戊醇-柴油（D85P15）、20%正戊醇-柴油（D80P20）作为燃料，在1900 m海拔环境下进行了试验。研究表明：在外特性工况下，与柴油相比，燃用D85B15和D85P15的柴油机动力性略有下降，燃用D85P15的柴油机有效热效率最高。燃用D85B15的NOx排放略低于柴油，最高降低3.33%；而D85P15的NOx排放有所增加，最高增加2.85%。在低负荷工况下燃用国五柴油时DOC+CDPF对CO的转化效率明显高于燃用D80P20时，2000 r/min时燃用柴油时CO转化效率高达96.8%，而D80P20只有36.9%。低速高负荷工况下燃用国五柴油与D80P20时，DOC对排气温度的提升作用均比较明显，平均提升41.8 ℃和42.5℃。燃用D80P20时DOC+CDPF压差升高较慢，压差最高比燃用国五柴油低6 kPa，DOC后端平均温度比燃用国五柴油高10 ℃。柴油机燃用D80P20在高负荷尤其是低转速高负荷时可有效降低颗粒物排放，降低DOC+CDPF压差。 英文摘要: In order to study the effect of oxygenated blended fuels on the diesel engine emissions and the low temperature oxidation and regeneration characteristics of a diesel oxidation catalyst(DOC) coupled catalytic diesel particulate filter(CDPF) aftertreatment system, a comparison of three oxygenated blended fuels and a pure diesel fuel was carried out on a 4-cylinder high pressure common rail diesel engine at an altitude of 1900 m. Study indicates that in the case of engine mapping(maximum torque conditions), the power performance of running with 15% biodiesel/diesel fuel and 15% n-pentanol/diesel fuel, respectively is lower than the diesel fuel operation, while the thermal efficiency with 15% n-pentanol/diesel fuel operation is the highest, and the NOx emissions with 15% biodiesel/diesel fuel is slightly lower than the diesel fuel operation with a highest drop of 3.33%, while the NOx emissions from the 15% n-pentanol/diesel fuel operation is increased by up to 2.85%. As observed, under low load conditions, when using diesel fuel, the conversion efficiency of DOC+CDPF to CO is significantly higher than the 20% n-pentanol/diesel fuel operation by up to 96.8%, and only 36.9% is obtained when using 20% n-pentanol/diesel fuel. Under low speed and high load conditions, when using diesel fuel and 20% n-pentanol/diesel fuel, DOC has a significant effect on the increase of exhaust temperature with an average rise of 41.8 ℃ and 42.5 ℃, respectively. The use of 20% n-pentanol/diesel fuel will increase the back pressure of DOC+CDPF slowly, the highest back pressure is 6 kPa lower than the diesel fuel operation, and the average temperature at the rear end of DOC is increased by 10 ℃. The use of 20% n-pentanol/diesel fuel can effectively reduce particulate emissions and pressure difference of DOC+CDPF at high load, especially at low speed and high load.

中文摘要: 为了获取两种脂肪酸酯类燃料棕榈酸甲酯和棕榈酸乙酯的热物理性质，并为将其作为燃料和燃料添加剂提供理论和试验数据支持，利用表面光散射法、振动管法和全反射法在较宽温区下分别研究了两种棕榈酸酯类的表面张力、黏度、密度和折射率。密度和折射率数据分别关联成了温度的多项式和线性函数，棕榈酸甲酯和棕榈酸乙酯的密度试验值与方程计算值平均绝对偏差分别为0.033%和0.013%，折射率试验值与方程计算平均偏差均为0.004%；黏度数据关联成了温度倒数的多项式，棕榈酸甲酯和棕榈酸乙酯的试验值与方程计算值平均绝对偏差分别为1.76%和2.30%；表面张力数据利用了van der Waals方程进行关联，棕榈酸甲酯和棕榈酸乙酯的试验值与方程计算值平均绝对偏差分别为0.86%和1.70%。 英文摘要: To provide theoretical basis and test data support for methyl palmitate and ethyl palmitate, which are two fatty acid esters, to be used as fuels or fuel additives in diesel engine, their thermophysical properties including surface tension, viscosity, density and refractive index were investigated in a wide temperature range by the surface light scattering, vibration tube and total reflection. The test data of the density and refractive index of both palmitates were correlated respectively as polynomial and linear functions of temperature. The average absolute deviations of density values calculated with the polynomial functions from the test data were 0.033% and 0.013% respectively, and both the average absolute deviations of refractive index values calculated with the liner function from the test data were 0.004%. The test data of the viscosities of both palmitates were correlated as polynomial functions of the reciprocal of temperature, and the average absolute deviations of these values calculated with the polynomial functions from the test data were 1.76% and 2.30% respectively. The test data of the surface tension of both palmitates were correlated as the van der Waals type functions, and the average absolute deviations of these values calculated with the van der Waals type functions from the test data were 0.86% and 1.70% respectively.

中文摘要: 使用格子玻尔兹曼方法对二维不混溶、不可压缩流体的Kelvin-Helmholtz（K-H）不稳定性进行数值模拟。以卷起高度 H 作为参考值，研究了密度比、表面张力、切应力对流体K-H不稳定性内产生Rayleigh-Taylor（R-T）不稳定性的影响。研究结果显示，密度比对两种不稳定性耦合起决定性作用。密度比接近1时，K-H不稳定性中不会产生R-T不稳定性，随着密度比增大，K-H不稳定性中开始产生R-T不稳定性。表面张力系数的增大对流体产生K-H不稳定性及两种不稳定性的耦合的卷起高度变化没有影响,但会对流体向内运动起抑制作用，且卷起流体的厚度明显增加。切应力对两种流体不稳定性的耦合起抑制作用。 英文摘要: By using the lattice Boltzmann method, the Kelvin-Helmholtz instability of two dimensional immiscible and incompressible fluids was numerically simulated. Taking the rolling height H as a reference value, the effects of density ratio, surface tension and shear stress on the appearance of Rayleigh-Taylor (R-T) instability in Kelvin Helmholtz(K-H) instability was studied. The results show that the density ratio plays a decisive role in the coupling effect of the two instabilities. When the density ratio is close to 1, the R-T instability does not occur in the K-H instability. When the density ratio increases, the R-T instability begins to occur in the K-H instability. An increase in the surface tension coefficient has no effect either on the K-H instability, or on the coupling height variation of the two instabilities, but it has an inhibitory effect on the inward movements of the fluids, and the thickness of the rolled fluid is significantly increased. The shear stress has an inhibitory effect on the coupling of the K-H instability and R-T instability.

中文摘要: 针对船用低速柴油机各缸和各循环间燃烧不平衡性问题，以6EX340EF型船用低速柴油机为研究对象，使用AVL Cruise M软件开发了具有各缸和各循环间的压力波动功能且满足准确性和实时性要求的仿真模型；结合NI CompactRIO硬件和NI LabVIEW软件，开发了缸压闭环控制快速原型，通过位置管理模块和缸压采集分析处理模块，从缸压数据中提取平均指示压力和50%燃烧放热量相位作为反馈变量，以喷油正时和喷油脉宽为控制变量，对缸压进行闭环控制；集成实时仿真模型、硬件在环仿真系统和快速控制原型，构成闭环系统。试验验证表明：开发的缸压闭环控制策略能够使燃烧特性参数波动减少50%左右，对各缸和各循环间的燃烧不平衡性均有改善效果。 英文摘要: Taking a 6EX340EF low-speed marine diesel engine as the research object, the issue of the combustion imbalance between the cylinders and working cycles of low-speed marine diesel engines was studied using the in-cylinder pressure feedback control technology. A simulation model with pressure fluctuations between the cylinders and working cycles was developed using the AVL Cruise M software to meet accuracy and real-time requirements, and a rapid control prototype was also developed based on the NI CompactRIO hardware and NI LabVIEW software. The closed-loop adjustment of the in-cylinder pressure was accomplished by using combustion characteristic parameters as feedback variables, such as indicated mean effective pressure and 50% combustion heat release phase extracted from the pressure in cylinder through position management module and cylinder pressure acquisition analysis processing module, and injection timing and injection pulse width as control variables. Then the real-time simulation model, hardware-in-loop simulation system and control prototype were integrated to form a closed-loop system. The test results show that the proposed in-cylinder pressure feedback control strategy can reduce the pressure fluctuation by about 50%, and it has an improvement effect on the reduction of the combustion imbalance between the cylinders and working cycles.

中文摘要: 以某3缸增压直喷汽油机正时皮带怠速低频噪声为研究对象，通过试验锁定噪声源和噪声频段，并对该噪声产生机理进行分析。针对该噪声源和噪声频段，通过一维动力学仿真的方法来优化正时皮带系统的布置参数，寻找到降低该噪声的方法，并最终通过噪声-振动-平顺性（NVH）试验验证了提高皮带刚度和增加小惰轮的方案能够有效降低该噪声。 英文摘要: The low-frequency noise of the timing belt of a three-cylinder turbocharged direct injection gasoline engine at idle speed was studied. The noise source and noise frequency spectrum were derived by test. The mechanism of noise generation was also analyzed. According to the obtained noise source and spectrum, the layout parameters of the timing belt system were optimized by the one-dimensional dynamic simulation. The method to reduce the noise was worked out and verified by noise vibration and harshness test. It is to increase the stiffness of the timing belt and add an idler.