Abstract
The in-cylinder flow field plays a key role in determining the combustion performance of internal combustion engines (ICEs) and it is critically important to validate numerical simulations of the flow field by comparison to experimental measurements using techniques such as particle image velocimetry (PIV). With the current trend for high-speed diagnostics, methods for quantitative comparison of vector fields are required which can provide robust spatially averaged results, without inspection of individual flow fields. The quality of match between vector fields, when quantified using current metrics such as the relevance index (RI), can be overly sensitive to the alignment of regions of low velocity such as the tumble vortex centre. This work presents complementary metrics, weighted using a function of the local velocity, for robust quantification of the alignment and magnitude differences between vector fields, the weighted relevance index (WRI) and the weighted magnitude index (WMI). These metrics are also normalized and combined in the combined magnitude and relevance index (CMRI). PIV measurements taken up to every 2 crank angle degrees within the tumble plane of a motored, optically accessible ICE are used to demonstrate the motivation for development and the application of the WRI, WMI, and CMRI metrics. The metrics are used to determine the number of cycles required to provide a representative mean flow field and to identify single cycles of interest. Variability of the flow field is quantified using the metrics and shows high variability in the region of the spark plug near typical ignition timings.Graphic abstract
Highlights
The internal combustion engine (ICE) remains the most common form of powertrain used in ground transportation throughout the world (Kalghatgi 2018)
Further understanding of the complex in-cylinder processes that affect mixture preparation and combustion are required to reduce fuel consumption and harmful emissions. In both industry and research, computational fluid dynamics (CFD) is a common tool used to simulate the performance of ICEs and provide data that can be used to improve the design of new combustion systems (Hentschel et al 2001)
Particle image velocimetry measurements were made in the central tumble plane of a single-cylinder, optically accessible GDI engine under motored conditions
Summary
The internal combustion engine (ICE) remains the most common form of powertrain used in ground transportation throughout the world (Kalghatgi 2018). It is highly likely that the ICE will play a key role in ground transportation in the coming decades For this reason, the continued development of combustion engines is necessary to meet the increasingly stringent emissions and fuel economy legislation enforced by governments across the world. Further understanding of the complex in-cylinder processes that affect mixture preparation and combustion are required to reduce fuel consumption and harmful emissions In both industry and research, computational fluid dynamics (CFD) is a common tool used to simulate the performance of ICEs and provide data that can be used to improve the design of new combustion systems (Hentschel et al 2001). In-depth validation of CFD using PIV flow fields requires the application of quantitative metrics for comparisons between simulated and experimental vector fields
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
