【作者】 陈涛；

【导师】 张扬军；

【作者基本信息】 清华大学 ， 动力工程及工程热物理， 2010， 博士

【摘要】 通过涡轮增压缩小发动机排量,是汽车节能与CO₂减排的主要技术途径之一。增压导致发动机工况适应性差,是车用发动机缩小排量所面临的主要难点和技术瓶颈。当前增压压气机设计与发动机循环性能研究相互独立,压气机设计在改进发动机工况适应性中的重要作用没有充分体现。论文针对增压发动机工况适应性差,无法满足汽车节能减排对车用发动机增压技术要求这个主要难点,提出了从压气机多工况设计角度改进增压发动机工况适应性的新思路。以某型车用增压汽油机为研究对象,研究了压气机全工况特性对发动机性能的影响,建立了压气机全工况通流模型,并对提高发动机工况适应性的压气机多工况通流设计方法等进行了探讨。论文工作主要包括以下几个部分。论文跨越增压压气机设计与发动机循环性能研究的界限,探讨了压气机全工况特性对发动机循环全工况性能的影响。研究表明,非匹配工况的压气机特性对发动机性能影响较大,改进发动机低速和中小负荷工况的压气机效率,可有效提高发动机全工况性能。论文研究了压气机全工况内部流动规律及性能影响机制,探讨了压气机进出口主要几何设计参数对压气机全工况性能的影响。叶轮进口相对直径、进口叶尖叶片角、出口相对宽度与出口后弯角等是影响压气机全工况性能的关键几何参数。论文建立了以关键几何设计参数为变量的压气机全工况通流模型。设计、试制加工了9个反映关键几何设计参数变化的压气机样机,利用试验数据对压气机全工况通流模型进行了标定与试验验证。论文基于压气机全工况通流模型,发展了以增压发动机全工况性能为设计目标、压气机关键几何参数为设计变量的压气机多工况通流设计新方法,突破了压气机设计优化与增压发动机循环性能优化相互独立的限制。论文采用压气机多工况通流设计方法,对某型1.8升增压汽油机压气机进行了设计改型。改型压气机的性能试验表明,多工况通流设计扩大了压气机的高效区范围,且使其高效区明显偏向低速小流量区域,并拓宽了喘振边界。仿真研究表明,压气机改型设计可使发动机低速转矩提高21%,部分负荷常用工况燃油消耗率下降2.4%,验证了压气机多工况通流设计方法的有效性。更多还原

【Abstract】 Much greater emphasis of turbocharging technology is being placed on downsizing the internal combustion engine （ICE） to increase fuel economy and reduce CO₂ emissions. But the fundamentally difference between rotating turbomachines and reciprocating piston engines lead to poor engine performance at off-design conditions, which is the main difficulty for engine downsizing. Traditionally, the turbocharger compressor design is independent from the engine system development process and the compressor is not usually designed for the improvement of ICE’s performance on all operation conditions.According to the key, a centrifugal compressor multi-point through-flow design approach was developed to improve the ICE’s overall performance. The influence of compressor characteristics on turbocharged engine system, sophisticated flow mechanism on different operation conditions and compressor multi-point design optimization was discussed. The thesis work contains contents as follows:The influence of different compressor characteristics on ICE’s performance on all operation conditions was investigated. The results show that the compressor off-design characteristics have great effect on engine performance. The location of compressor high efficiency island was the most influential factor for the ICE’s performance on low speed and part-load conditions.Through the detail research on a small turbocharger compressor internal flow mechanism, the acting factors which changed the compressor MAP characteristics were investigated. The main compressor geometrical parameters were discussed and it was found that four impeller structures, including inlet tip diameter, inlet tip blade angle, outlet width and outlet backsweep angle, have the greatest influence on compressor overall performance.Based on the inside flow mechanisms of centrifugal compressors, a through-flow model was developed to predict the compressor overall performance with various structure parameters. The model was calibrated and validated with the test data of nine different compressors. Based on the through-flow model, a compressor multi-point through-flow design approach was developed with the objective of ICE’s performance for all operation conditions. During the through-flow design process, the direct influence of compressor geometry parameters on ICE’s overall performance can be considered.The multi-point through-flow design approach was successfully applied to a 1.8L turbocharged gasoline engine to develop a new turbocharger compressor. The efficiency has been improved obviously on low flow rate conditions of the new designed compressor. Simulation resultes show that the low-end torque of the turbocharged gasoline engine matched with the new compressor has been increased by 21% and part-load fuel consumption has been decreased by 2.4%.更多还原