New combustion concepts and engine designs are being currently investigated in order to comply with upcoming pollutant regulations and reduce fuel consumption. In this context, two-stroke architectures appear as a promising solution for the implementation of some combustion concepts. However, scavenging processes in a two-stroke engine are much more challenging than for a four-stroke engine, and the residual mass of burnt gases retained inside the cylinder needs to be properly determined in order to keep control over the in-cylinder composition, hence over the combustion conditions and pollutant emissions. In this study, a new methodology for the estimation of the internal residual gas fraction is introduced, which is based on the thermodynamic processes occurring in the engine investigated and makes use of basic engine instrumentation and measurement equipment usually available in a conventional test cell. Several versions of the estimator were developed so that different requirements could be met, such as those of real-time estimation on an engine test bench but with reduced precision or, on the contrary, highly precise but time-consuming computations for post-processing purposes and combustion diagnosis. The consistency of the internal residual gas estimator was then validated through its application to real engine tests at different operating points.

中文翻译：

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二冲程高速直喷压燃发动机进气门关闭时缸内残余质量分数的估算

目前正在研究新的燃烧概念和发动机设计，以符合即将出台的污染物法规并降低燃料消耗。在这种情况下，二冲程架构似乎是实现某些燃烧概念的有前途的解决方案。然而，二冲程发动机的扫气过程比四冲程发动机更具挑战性，并且需要正确确定保留在气缸内的已燃烧气体的残余质量，以保持对缸内成分的控制，因此超过燃烧条件和污染物排放。在这项研究中，引入了一种估计内部残余气体分数的新方法，它基于所研究的发动机中发生的热力学过程，并利用通常在传统测试单元中可用的基本发动机仪器和测量设备。开发了多个版本的估算器，以便满足不同的要求，例如在发动机测试台上进行实时估算但精度降低，或者相反，用于后处理目的的高精度但耗时的计算和燃烧诊断。然后通过将其应用于不同操作点的实际发动机测试来验证内部残余气体估计器的一致性。例如在发动机测试台上进行实时估计但精度降低，或者相反，用于后处理目的和燃烧诊断的高精度但耗时的计算。然后通过将其应用于不同操作点的实际发动机测试来验证内部残余气体估计器的一致性。例如在发动机测试台上进行实时估计但精度降低，或者相反，用于后处理目的和燃烧诊断的高精度但耗时的计算。然后通过将其应用于不同操作点的实际发动机测试来验证内部残余气体估计器的一致性。