Numerical simulation investigation on influencing factors of liquid film spreading from an oblique jet impinging on a wall

The spreading behavior of a liquid film formed by oblique jet impingement directly influences the efficiency and uniformity of film cooling in liquid rocket engines. In this study, numerical simulations based on the volume of fluid (VOF) model were conducted, and an experimental system was established to measure film morphology and thickness for validation. The results show good agreement between the simulation and experiment, with relative deviations in film width and thickness of 20% and 10%, respectively, confirming the model's accuracy and applicability. On this basis, the effects of jet velocity, jet angle, jet orifice diameter, and wall contact angle on film spreading characteristics were systematically investigated. The results indicate that the increasing jet velocity and jet orifice diameter significantly increase the liquid film width and length. Increasing the jet angle increases the overall spreading area while reducing its streamwise length and increasing its width. Increasing the contact angle reduces the spreading area. Further sensitivity analysis reveals that the liquid film width is primarily influenced by the jet velocity and jet angle; the liquid film length is jointly determined by the jet velocity and jet orifice diameter; the jet orifice diameter predominantly governs the thickness in the thin-layer zone; and the thickness in the rise zone is jointly controlled by the jet angle and jet orifice diameter. These findings elucidate the key factors governing liquid film spreading characteristics, thereby providing theoretical guidance for the design and optimization of liquid-film cooling in liquid rocket engines.