Study of the thickness of the liquid film formed by a round water jet impinging on a curved cylindrical wall

Abstract

An experimental setup has been established to investigate the thickness profiles of the liquid film formed by an oblique round water jet impinging on curved walls. The influence of the jet velocity, jet angle, and radius of curvature of the curved wall on the thickness profile of the liquid film has been investigated. Both on the flat and curved walls, as the jet velocity increases, the mode of the liquid film transitions from laminar to turbulent, and the thickness of the liquid film decreases first and then increases along the flow direction. The transition velocity range for the curved walls with the radius of curvature R = 30 mm is 19.1–25.08 m/s (Re = 10 946–14 373). Both on the flat and curved walls, the thicknesses of the liquid film increase in the downstream part of the liquid film while decreasing in the upstream part, as the jet angle increases. The laminar and turbulent thickness prediction models of liquid film on flat walls were extended to curved walls by replacing the distance away from a stagnation point with the radius of curvature. Predictions obtained by the present models agree well with measurements. Errors of the film thickness between the predictions and measurements along the centerline are mainly less than 20%, and the correlation coefficients (σc) are mainly located in 0.85–0.99.