Inclined free-surface liquid jet impingement on semi-cylindrical convex curved and flat surfaces: Heat transfer characteristics

An experimental study was performed to understand heat transfer characteristics of inclined liquid jet impingement on heated semi-cylindrical convex curved and flat surfaces in free surface configuration (unconfined). In experiments, curvature ratio of D/d = 7 along with the flat surface (D/d → ∞) were considered, here d is the hydraulic diameter of the circular pipe used to produce a liquid jet, and D is the cylindrical surface's diameter. Jet to plate spacing (H) was held constant to 24 mm (H/d = 4). Results are presented for four different inclination angles [0° (orthogonal jet), 15°, 30°, 45°], and Reynolds numbers (17,036 to 42,590). Applicability of inclined jet impingement on a curved and flat surface, their advantage, disadvantages in terms of heat removal rate (Nusselt number) are discussed. A Parametric study was performed by varying Reynolds number, inclination angle, and curvature ratios (D/d) to understand these parameters' effect on heat transfer. Findings revealed that higher inclination angle cases (θ = 30° and θ = 45°) could give an overall high heat removal rate from the cylindrical surface as compared to the orthogonal jet case, especially for higher Reynolds numbers. However, there are no advantages in terms of the heat removal rate by using an inclined jet for lower Reynolds number cases.