Efficient combustion in modern engines depends not only on injector spray quality but also on the spatial coordination between the spray plume and in-cylinder airflow structures. While many studies qualitatively describe spray–flow interaction, quantitative evaluation of their spatial matching characteristics remains limited. This study presents a Particle Image Velocimetry (PIV)–based experimental investigation focused on the spatial coordination between injector spray development and combustion chamber flow structures.
Experiments are conducted in an optically accessible chamber designed to reproduce simplified in-cylinder flow conditions. Controlled swirl and cross-flow fields are generated independently of the injection process, allowing systematic variation of flow intensity and direction. A high-pressure injector is installed with adjustable orientation to investigate the influence of spray alignment relative to dominant airflow structures.
PIV measurements are performed to capture two-dimensional velocity fields at different stages of spray evolution. Instead of focusing solely on instantaneous interaction, this study analyzes the spatial overlap between high-momentum spray regions and high-velocity airflow zones. A spatial coordination coefficient is introduced based on velocity vector alignment and momentum distribution overlap, enabling quantitative assessment of spray–flow matching quality.
Results show that optimal spatial coordination occurs when the spray penetration path intersects regions of moderate airflow velocity rather than maximum flow intensity. Excessively strong airflow tends to distort the spray plume and reduce penetration stability, while weak airflow limits air entrainment efficiency. PIV data reveal that well-coordinated conditions produce smoother velocity transitions and more evenly distributed turbulence around the spray boundary.
Time-resolved analysis further indicates that spatial coordination evolves dynamically during injection. In the early injection phase, spray momentum dominates the local flow field, whereas in later stages, airflow structures increasingly influence spray dispersion and redirection. Poor coordination leads to localized stagnation zones and asymmetric vortex formation, which may negatively affect mixture homogeneity.
The study also compares different nozzle spray angles under identical flow conditions. Results demonstrate that nozzle geometry plays a critical role in achieving spatial coordination, as appropriate spray angles can adapt more effectively to the inherent flow pattern of the combustion chamber.
In conclusion, this PIV-based study provides a quantitative framework for evaluating spatial coordination between injector spray fields and combustion chamber flow structures. The proposed analysis method offers valuable guidance for injector orientation optimization and combustion chamber flow design, contributing to improved mixture preparation and combustion efficiency.
