Pressure Trace Analysis Methods to Analyze Combustion Features and Cyclic Variability of Different Gasoline Combustion Concepts

Pressure Trace Analysis (PTA) is the basis for any combustion concept development and analysis of its combustion features. Cyclic variability analysis is also addressed using PTA, for example by means of heat release calculation. To fulfill that requirement with a low computational effort, methods for reliable fast heat release calculation of single cycles are presented. A new approach to determine the temperature in the burnt zone of a 2-zone-model is introduced as well. These PTA methods were applied to chosen combustion concepts at a representative operation point: 2000/3 bar imep (work integral over 720 cad). The gasoline combustion concepts used in this study are: homogeneous charge stoichiometric spark ignition (SI) using standard valve-train and additionally using a variable valve-train regarding lift and timing (VVA); stratified charge spray guided direct injection (SGDI) and homogeneous charge compression ignition (HCCI). The combustion concepts investigation will comprise an analysis on a cycle-to-cycle basis and statistic analysis is also presented in this article. Selected results showing the combustion features over each cycle are presented for each combustion concept and discussed. Additionally, histograms and correlation diagrams of the combustion features will provide more insight in the combustion behavior, especially on cyclic variability and its inherent efficiency loss.