采用相继增压改善船用柴油机排放的数值模拟

Numerical simulation on reducing emission of marine diesel engine by STC

为了减少船舶柴油机的有害排放,在TBD234V12船用柴油机原机常规增压系统的基础上,进行了大小涡轮增压器3区相继增压设计,建立了TBD234V12船用柴油机采用大小增压器3区相继增压的准维仿真模型.应用试验实测的标况缸压曲线验证了计算模型的有效性,且在该柴油机作为船舶主机推进特性工况下,对常规增压系统原机的油耗、涡前排温的计算结果与试验结果进行对比,吻合较好,验证了模型在变工况条件下的准确性.对采用大小增压器3区相继增压柴油机推进特性工况的排放进行数值模拟研究,结果表明:在1TC-S,1TC-L和2TC区相继增压NO x和Soot值比原机常规增压在中低负荷工况下的排放浓度都有明显的降低,燃油消耗率也有所下降,为船用柴油机采用大小增压器相继增压降低排放提供了理论依据.

In order to reduce the harmful emissions of diesel engines,three phases sequential turbocharging（STC） system of unequal size turbochargers was designed based on the original turbocharging system of TBD234V12 marine diesel engine.A quasi-dimensional simulation of three phases STC system of TBD234V12 diesel engine with unequal size turbochargers was established.According to the cylinder pressure curve measurement under calibration conditions,the effectiveness of the simulation calculating model was verified.Using diesel engine as marine main engine,the calculating results of the specific fuel consumption of original machine and the exhaust temperature before turbine of original engine were compared with testing results.The accuracy of the numerical simulation under the variable condition was verified by the comparison.Numerical simulation on emissions under the condition of propulsion characteristic was investigated.The results show that compared to the original engine,the emission concentrations of NOx and Soot at three phases of 1TC-S,1TC-L and 2TC are significantly decreased under low load condition,and the specific fuel consumption is also decreased.The results provide a theoretical basis for reducing emission of marine diesel engine with sequential turbocharging system.