增压柴油机采用EGR 后，可以降低进气中的氧含量，降低燃烧放热率的峰值，降低燃烧的最高温度，从而降低NOx 的排放。由于废气的温度较高，进入气缸的充量温度将会升高，燃烧温度升高。为了有效降低NOx 的排放，可以对EGR 进行冷却。本文用试验的方法研究了EGR 温度对缸内压力、燃烧放热规律、燃烧温度以及NOx 排放等参数的影响。结果表明，对EGR 进行冷却可以降低燃烧初期的压力升高率和峰值压力。低的EGR 温度可以延长燃烧滞燃期，增大预混合燃烧的比例，缩短燃烧持续期，降低最高燃烧温度，从而降低NOx 的排放，同时可以降低炭烟的排放，提高燃油经济性。

为节省涡轮增压可变谐振进气系统设计的时间和费用。本文研究了该系统模拟计算方法。其中进排气采用一维非定常流动模型。控制阀采用节流孔板模型。计算与试验结果的对比表明模拟计算方法是可行的。通过模拟计算分析了控制阀泄漏和开度对充量系散的影响。

采用进排气管流动为一维非定常模型的发动机循环模拟方法计算充气效率时，若模型中给定的参数不合适，可能引起充气效率的计算误差超过5%。为提高充气效率的计算精度，由模拟计算和相关试验，分析了管道的摩擦系数、弯管的压力损失系数、进气管壁和气缸壁温度及其传热系统对充气效率的影响程度。结果表明，进气管和气缸的传热对充气效率的影响较显著，而管道摩擦系数和弯管压力损失系数对充气效率的影响较小。

以一台D6114涡轮增压柴油机为研究对象，采用了一套带文曲利管的排气再循环系统进行了试验研究。试验结果表明，该系统在高工况下能克服平均排气压力低于平均进气压力的困难，方便地实现排气再循环。研究了在不同工况下柴油机的NOx排放，烟度和比油耗随EGR率的变化规律以及EGR的冷却效果对NOx排放的影响。

动力机械装置中广泛存在着非定常旋流流动现象，本文根据质量、动量、能量和旋流量矩守恒方程，建立了管内非定旋流流动的一维计算模型，并应用特征线方法推导出了其数值计算格式，是管内非定常一维流动计算的扩展，应用于一台四缸涡轮增压柴油机旋流排气管的计算，通过与实测压力波的比较，表明计算模型有较好的计算精度。

本文用激光多普勒测速仪测量发动机冷却水的流场，通过计算机绘制了缸头冷却水腔二维流场分布.为寻求发动机气缸头冷却水合理的流场分布。避免出现流动死区，使发动机在一定的冷却水流量下保证气缸头良好的冷却提供了基础。

A working process model for turbocharged direct injection (DI) diesel engines was developed by intensively analysing the in-cylinder spray and combustion process. The model can be used to prdeict the comprchensive performanace and Nox emission of turbocharged DI diesel engines under transient conditions. A transient test-bed was constructed, which was composed of a six-cylinde turbocharged DI diesel engine. a console, a measuring and control PC (personal computer) system for data collecting and exhaust gas sampling control in transient conditions and an exhaust gas sampling and measuring syatem. Tests of three types of transient operation conditons were carried out. These tests and model simulations show that the NOx emission laws are different during transient conditions and in some acceleration and load acceptance conditons NOx emissions are better than the corresponding steady state conditions.

以MPC二维排气管模型为对象，对其二维非定常流动进行了研究。在柴油机倒拖时，测量了该模型排气管内6个截面的压力和速度分布的变化，研究了热线探头标定前的预处理、实测状态与标定状态差异引起的误并修正和流动方向判别对速度测量的影响。测量结果显示，同一截面不同测点的压力变化曲线非常接近，支管的速度分布曲线是不对称的，其峰值偏向支管的内壁面，进入总管后速度曲线呈偏向总管外壁面的不对称分布，随后渐渐变为对称分布。测量结果还可用于排气二维非定常流动计算的边界条件和考核数据。

A phenomenological multizone combustion model is developed for use in the transieat condition analysis of a turbocharged direct injection (DI) diesel engine. The main processes in the cylinder, such as spray penetration, droplet evaporation, air-fuel mixing, spray wall interaction, ignition and fuel combustion, are taken into consideration. In order to predict cylinder pressure and NOx emissions in a wide range of engine speeds, loads and air-fuel ratios under transient conditions, the model has been improved in many respects, especially in the velocity distrbution of fuel spray, zonal entrainment and the calculation of gas properties and chemical equilibrium compositions of combustion products including solid earbon. With respect to the turbocharged engine with a high pressure in the cylinder, the compression factor is odded to the ideal gas equation of state in order to simulate cylinder pressure accurately. Cylinder pressure, heat release and NOx emission histories for different operating conditions are calculated for two types of engines. The agreement between calculated and measured results is good for a wide range of operating conditions. This indicates that the model has the ability to predict cylinder pressures and NOx emissions in both steady state and transient operating conditions.