【摘要】 基于三维仿真软件Converge构建了船用低速双燃料发动机仿真模型，并验证了模型的准确性．模拟了不同预燃室通道和天然气喷射阀结构下发动机的工作过程，并分析了不同参数优化燃烧和降低排放的潜力．结果表明：对预燃室通道的研究中，适度增加预燃室通道直径和长度均会促进引燃油着火，加快主燃室燃烧进程，但直径过大会增加NO_x排放，长度过长会抑制着火并增大点火能量损失；增加通道角度同样会加速燃烧，但当其与扫气角度一致时，角度越大，NO_x排放越高；对天然气喷射阀的研究中，降低阀门位置、增大喷射角度和减小阀门直径均会降低甲烷逃逸量；喷射角度对主燃室涡流比的影响较大，当喷射角度与扫气角度相反时，喷射角度越大，燃烧越快，NO_x排放越低；适度减小阀门直径可提高天然气射流速度，进而加速燃烧．更多还原

【Abstract】 A 3D simulation model was constructed for a low-speed dual-fuel marine engine based on Converge and the modelling accuracy was verified through engine bench test.The engine operation process under different prechamber passage structures and natural gas injection valve structures were simulated,and the potential of parameter optimization to improve combustion and reduce emissions was analyzed.The research results on the pre-chamber passage structure show that appropriately increasing the diameter and length of the pre-chamber channel will promote the ignition of the pilot fuel and accelerate the combustion process of the main combustion chamber.However,an excessive diameter will increase NO_x emissions and an excessive length will inhibit ignition and increase ignition energy loss.Increasing the channel angle also accelerates combustion,but when it is consistent with the scavenging angle,the larger the angle,the higher the NO_x emissions.Research results on natural gas injection valves show that lowering the valve position,increasing the injection angle and reducing the valve diameter will reduce methane escape.The injection angle has a great influence on the swirl ratio of the main chamber.When the injection angle is opposite to the scavenging angle,the larger the injection angle,the faster the combustion and the lower the NO_x emissions.Moderately reducing the valve diameter can increase the natural gas jet velocity,thereby accelerating combustion.更多还原