K-means clustering-driven detection of time-resolved vortex patterns and cyclic variations inside a direct injection engine

•K-means clustering method is applied to reveal transient vortex behavior.•Proposed method can cluster vortices into zones with flow features retained.•Vortex misrecognition due to temporal averaging is mitigated with K-means approach.•New K-means clustering capabilities are unveiled to quantify cyc...

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Bibliographic Details
Published in:Applied thermal engineering Vol. 180; p. 115810
Main Authors: Zhao, Fengnian, Hung, David L.S., Wu, Shengqi
Format: Journal Article
Language:English
Published: Oxford Elsevier Ltd 05.11.2020
Elsevier BV
Subjects:
Aerodynamics
Algorithms
Cluster analysis
Clustering
Cyclic variations
Cylinders
Diesel engines
Fluid dynamics
Fluid flow
Fuel-air mixing
Heat transfer
Internal combustion engines
K-means clustering
Pattern recognition
Thermodynamic efficiency
Time-resolved vortex pattern detection
Vector quantization
Vortices
Time-resolved vortex pattern detection
Cyclic variations
K-means clustering
ISSN:1359-4311, 1873-5606
Online Access:Get full text
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Summary:•K-means clustering method is applied to reveal transient vortex behavior.•Proposed method can cluster vortices into zones with flow features retained.•Vortex misrecognition due to temporal averaging is mitigated with K-means approach.•New K-means clustering capabilities are unveiled to quantify cyclic flow variations. Time-resolved vortices are indispensable rotational flow structures which impact fuel-air mixing, combustion, and thermal efficiency of internal combustion engine. In-cylinder flow fields are largely stochastic, therefore capturing full spatial and temporal details of in-cylinder vortex behavior not only requires enormous datasets, but also time-efficient analysis methods. The loss of transient vortex information often becomes problematic due to temporal averaging of spatial vortex features. In this study, a two-step vortex pattern detection and quantification scheme with a novel application of K-means algorithm was implemented to investigate the transient vortex dynamics and cyclic variations inside an optical direct injection engine. A vortex pattern recognition method was first implemented to locate the vortices which appeared intermittently in each cycle. Then, the K-means algorithm was applied to cluster the vortex zone characteristics of consecutive engine cycles. Results show that vortex detection based on K-means algorithm can efficiently and accurately cluster the vortex centers into different zones and quantify their cyclic variations. It is also capable of minimizing the issue of vortex misidentification due to temporal averaging. This work demonstrates the application of K-means algorithm to detect the dynamic nature of vortex motions and provides a quantitative analysis on flow vortex characteristics and cyclic variations.
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ISSN:1359-4311
1873-5606
DOI:10.1016/j.applthermaleng.2020.115810