A Novel Model for Computing the Trapping Efficiency and Residual Gas Fraction Validated with an Innovative Technique for Measuring the Trapping Efficiency

Research output: Chapter in Book/Report/Conference proceedingPaper in conference proceeding


The paper describes a novel method for calculating the residual gas fraction and the trapping efficiency in a 2 stroke engine. Assuming one dimensional compressible flow through the inlet and exhaust ports, the method estimates the instantaneous mass flowing in and out from the combustion chamber; later the residual gas fraction and trapping efficiency are estimated combining together the perfect displacement and perfect mixing scavenging models. It is assumed that when the intake port opens, the fresh mixture is pushing out the burned charge without any mixing and after a multiple of the time needed for the largest eddy to perform one rotation, the two gasses are instantly mixed up together and expelled. The result is a very simple algorithm that does not require much computational time and is able to estimate with high level of precision the trapping efficiency and the residual gas fraction in 2 stroke engines. The tuning and the validation of this algorithm are performed by measuring the trapping efficiency. These measurements are conducted with an innovative technique which consists in measuring the inlet and exhaust temperature, and calculation of the blow down temperature from the pressure trace. The model was tested using a mini high speed 2 stroke HCCI engine fuelled with diethyl ether between 10,800 and 19,000 [rpm].


Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Other Mechanical Engineering


  • Internal Combustion Engines, Two-Stroke
Original languageEnglish
Title of host publicationSAE Technical Paper Series
PublisherSociety of Automotive Engineers
Publication statusPublished - 2008
Publication categoryResearch
EventSmall Engine Technology Conference & Exposition, 2008 - Milwaukee, Wisconsin, United States
Duration: 2008 Sep 92008 Sep 11

Publication series

ISSN (Print)0148-7191


ConferenceSmall Engine Technology Conference & Exposition, 2008
Abbreviated titleSETC
CountryUnited States
CityMilwaukee, Wisconsin