Sanapo C., Ruiz S.G., Courtiaud S., Laboureur D., 2025, Large-scale Characterization of the Atmospheric Dispersion Velocity and Concentration of Supersonic Underexpanded Jets, Chemical Engineering Transactions, 116, 685-690.
The present work investigates the velocity and concentration fields of underexpanded jets discharging into quiescent and boundary-layer flow conditions using large-scale planar particle image velocimetry (PIV) and Mie-scattering. Experiments were conducted at the von Karman Institute, employing a high-pressure tank with an orifice nozzle to replicate jet leakage scenarios under two upstream pressure ratios and two boundary layer velocities. The results confirm self-similarity in velocity and concentration profiles for jets in quiescent atmospheres, with normalized profiles collapsing across transition and far-field zones. However, increasing the boundary layer velocity disrupts the jet symmetry, altering the Gaussian tail of the velocity profile and enhancing jet dispersion. The decay rates of centerline velocity and concentration highlight the interplay between upstream jet momentum and external boundary-layer dynamics. Scaling analysis demonstrates the consistency of the results, aligning with theoretical models for fully expanded jets. These findings provide insights into the transport mechanisms of underexpanded jets, underscoring the role of ambient conditions in modifying jet behavior. The outcomes are valuable for applications involving jet dispersion in industrial and environmental contexts, offering a robust experimental framework to model and predict jet flow dynamics.
