Entrainment and Drag Forces of Deflected Jets

Experiments were carried out on a round turbulent jet with a Reynolds number of 2x10⁵ discharged perpendicularly into crossflows in a wind tunnel. The jet-to-crossflow velocity ratio ranged from about two to nine. The drag force resulting from the pressure distribution around the jet was found to make a significant contribution to the momentum uptake by the jet only in the region just above the jet origin, while the momentum of the entrained fluid makes its principal contribution over the reach, where the jet has become fully developed, but is not yet extensively deflected. Integral-type analyses were developed, by solving the integrated equations of mass and momentum conservation and the kinematic relation, to predict jet behavior in the near-field, curvilinear, and far field regions. The entrainment velocity was related to two components of the jet velocity relative to the crossflow velocity. The drag force on the jet was considered only in the near-field, jet dominated region. Values of the entrainment and drag coefficients were inferred from the experimental data analyzed within the framework of the analytical model.