Flow effects due to valve and piston motion in an internal combustion engine exhaust port
2015 (English)In: Energy Conversion and Management, ISSN 0196-8904, E-ISSN 1879-2227, Vol. 96, 18-30 p.Article in journal (Refereed) Published
Performance optimization regarding e.g. exhaust valve strategies in an internal combustion engine is often performed based on one-dimensional simulation investigation. Commonly, a discharge coefficient is used to describe the flow behavior in complex geometries, such as the exhaust port. This discharge coefficient for an exhaust port is obtained by laboratory experiments at fixed valve lifts, room tem- peratures, and low total pressure drops. The present study investigates the consequences of the valve and piston motion onto the energy losses and the discharge coefficient. Therefore, Large Eddy Simulations are performed in a realistic internal combustion geometry using three different modeling strategies, i.e. fixed valve lift and fixed piston, moving piston and fixed valve lift, and moving piston and moving valve, to estimate the energy losses. The differences in the flow field development with the different modeling approaches is delineated and the dynamic effects onto the primary quantities, e.g. discharge coefficient, are quantified. Considering the motion of piston and valves leads to negative total pressure losses during the exhaust cycle, which cannot be observed at fixed valve lifts. Additionally, the induced flow structures develop differently when valve motion is taken into consideration, which leads to a significant disparity of mass flow rates evolving through the two individual valve ports. However, accounting for piston motion and limited valve motion, leads to a minor discharge coefficient alteration of about one to two percent.
Place, publisher, year, edition, pages
Elsevier, 2015. Vol. 96, 18-30 p.
Internal combustion engines, Fuel economy, Turbocharged engines, Exhaust gas energy, Large Eddy Simulation
Fluid Mechanics and Acoustics
Research subject Vehicle and Maritime Engineering
IdentifiersURN: urn:nbn:se:kth:diva-161210DOI: 10.1016/j.enconman.2015.02.058ISI: 000353729200003ScopusID: 2-s2.0-84924262331OAI: oai:DiVA.org:kth-161210DiVA: diva2:794013
FunderSwedish Energy Agency
QC 201503112015-03-102015-03-102015-11-17Bibliographically approved