【作者】 李琦；

【导师】 王银燕；

【作者基本信息】 哈尔滨工程大学 ， 轮机工程， 2010， 硕士

【摘要】 相继增压技术是改善中高速大功率柴油机低负荷性能最有效的措施之一。为了提高某16V型船用柴油机的低负荷性能,本文以GT-POWER和STAR-CD软件为平台,对该柴油机进行了相继增压系统性能分析和结构设计。本文首先采用GT-POWER软件建立了柴油机常规增压工作过程的仿真模型,模型计算结果与实验数据吻合较好,证明了可以在此仿真模型基础上进行相继增压计算。在此基础上对该机采用相继增压进行计算分析,并初步确定了相继增压的切换点。计算结果表明该机采用相继增压技术后,按螺旋桨特性,在40%以下负荷运行时,燃油消耗率降低了3.3g/(kW·h)～20g/(kW·h),增压压力提高了0.02MPa～0.09MPa,排气温度降低了60K ~104K,低负荷性能显著提高。在该柴油机相继增压稳态仿真模型基础上,建立了相继增压瞬态模型,对相继增压切换过程中参数变化进行了计算分析,初步确定了受控增压器的切换延迟,为相继增压控制系统的设计提供了参考。相继增压系统的结构主要包括控制阀门与进排气系统。本文对燃气阀和空气阀的选型进行了计算分析,确定了满足该相继增压系统的阀门类型和尺寸,通过对燃气阀流道流场的计算分析,确定了燃气阀安装位置。本文对排气系统进行了研究。设计了三种排气连通支管,采用三维数值模拟方法,通过对计算结果比较分析,得到了适合该柴油机相继增压的排气连通支管。一维/三维耦合计算模型,既考虑了一维模型中的动态效应,又能体现三维结构对柴油机性能的影响。本文应用GT-POWER和STAR-CD软件建立了一维/三维耦合模型,得到了排气管不同曲轴转角时刻的速度分布,较真实地模拟出柴油机间歇排气的情况,反映出排气管结构对流动的影响,为排气系统的优化提供了依据。更多还原

【Abstract】 The sequential turbocharging (STC) technology is one of the most effective methods to improve the low condition performance of the highly turbocharged diesel engines. In this paper, in order to improve the low load performance of a 16V-type marine diesel engine, the structure of the STC is designed by using the software of GT-POWER and STAR-CD.By using GT-POWER software, a calculating model of the 16V-type turbocharging diesel working process is set up. The calculated results tend to be in agreement with the experimental ones and then the STC diesel working process model is built. The results indicate that after employing STC,the diesel engine improves its low load performance distinctively. Based on the steady performance simulation model, the transition model is built for the STC diesel. The status switch process of the sequential is studied, and the calculated results show that the butterfly delay time step must be set properly during the controlled turbocharger switch-in process, that is the air valve must be opened later than gas valve, if the time step is too short, then the controlled turbocharger may be surge, but if the time step is too long, the basic turbocharger would appear unsteady phenomenon.The structures of the STC system include the control valves and the intake and exhaust system. The calculation and analysis of the selection of air valve and gas valve are done in this paper, gains the valve that satisfies the STC system and the installation position of the gas valve is determined.The exhaust system of the STC diesel is one of the main contents in this paper. Three types of the exhaust connective pipe model are designed. Then the three-dimensional mathematical models can be set up by using STAR-CD. And an appropriate type of the exhaust connective pipe can be obtained by analyzing the results comprehensively. One-dimensional and three-dimensional coupling model can not only consider the dynamic effect on one-dimensional model, but also reflect on the diesel engine performance influenced by three-dimensional structure. Based on the software of GT-POWER and STAR-CD, a one-dimensional and three-dimensional coupling model for the STC diesel is set up. This model can simulation the actual intermittent operation of the exhaust system, and gains the velocity distributing at different crank angle. The results has provided the evidence for the exhaust system design and set the stage for the further research.更多还原