A computational fluid dynamics model of the marine diesel engine was established and validated, and the simulation studies were carried out using this model. Different gravity conditions were set in the computational fluid dynamics model to investigate their effect on marine diesel emissions and performance. By comparing the simulation results under different basic grid sizes, 1.2 mm was selected as the basic grid size of the computational fluid dynamics model. The model uses the experimental data including cylinder pressure, heat release rate, and nitrogen oxides (NO_x) emissions to calibrate and validate the model. The simulation results are very close to the experimental data, and slight errors are also within the allowable range. In particular, when considering the heat transfer of the combustion chamber wall, the simulation results of the heat release rate are closer to the experimental data. The simulation results show that gravity has a slight effect on cylinder pressure and heat release rate, and has a certain degree of effect on fuel spray and atomization. The penetration length of the fuel is proportional to the gravity, and the maximum deviation of the Sauter mean diameter of the droplet is 25.74%. The spray and atomization process of fuel directly affects combustion and emissions. The maximum deviation of NO_x emissions is 6.03%, which is reduced from 7.46 to 7.01 g/kW·h. Finally, the three-dimensional simulation results of temperature, equivalence ratio, and NO_x emission of different crank angles under different gravity conditions are compared.

建立并验证了船用柴油机的计算流体动力学模型，并使用该模型进行了仿真研究。在计算流体动力学模型中设置了不同的重力条件，以研究它们对船用柴油排放和性能的影响。通过比较不同基本网格尺寸下的仿真结果，选择1.2 mm作为计算流体动力学模型的基本网格尺寸。该模型使用的实验数据包括气缸压力，放热率和氮氧化物（NO _x）排放，以校准和验证模型。仿真结果与实验数据非常接近，轻微误差也在允许范围内。特别地，当考虑燃烧室壁的热传递时，放热率的模拟结果更接近实验数据。仿真结果表明，重力对气缸压力和放热率影响不大，对燃油喷雾和雾化有一定程度的影响。燃料的穿透长度与重力成正比，液滴的Sauter平均直径的最大偏差为25.74％。燃料的喷雾和雾化过程直接影响燃烧和排放。NO _x的最大偏差排放为6.03％，从7.46降至7.01 g / kW·h。最后，比较了不同重力条件下不同曲柄角的温度，当量比和NO _x排放的三维模拟结果。