Estimation of Entrainment Coefficient in Axisymmetric Jets Using Concentration-Based Velocity Derived from LIF Measurements

Código

III-FLUHIDROS0032

Autores

Adeleh Abdighortikolaei, Tobias Bernward Bleninger, Ozeair Abessi

Tema

01 - Mecânica dos Fluidos (Ensino, Hidráulica e Mecânica dos Fluidos Ambiental).

Resumo

This study presents a concentration-based approach for estimating the entrainment coefficient in a momentum-dominated axisymmetric turbulent jet. In the absence of direct velocity measurements, scalar concentration data obtained from Laser-Induced Fluorescence (LIF) experiments are used to reconstruct the centerline velocity through a proportional relationship between concentration and velocity. Based on the estimated velocity field, the entrainment coefficient is calculated using an integral formulation. The analysis is performed for three experimental cases with different Reynolds numbers and inlet velocities, while maintaining a constant nozzle diameter. The results show that the entrainment coefficient exhibits variations in the near-field region and gradually converges to an approximately constant value of 0.055 in the fully developed region. The findings indicate that the entrainment coefficient is only weakly influenced by Reynolds number in the self-similar region. Furthermore, the results are in good agreement with existing studies, supporting the validity of the proposed methodology. The normalized centerline velocity also demonstrates a consistent decay trend, further confirming the physical reliability of the approach. Overall, the proposed method provides a practical and reliable alternative for estimating entrainment characteristics when direct velocity measurements are unavailable, with potential applications in environmental flows, pollutant dispersion, and ventilation systems.