Film flow and micromixing behaviours of a turbulent jet impinging on a radially grooved spinning disk reactor

The film flow and micromixing behaviour of a turbulent jet impinging on a radially grooved spinning disk reactor were investigated. The results indicate that the number and depth of the grooves significantly influenced the formation of wavelet flow. Wavelet flow was achieved at lower rotational speeds, with an increased number and depth of grooves further reducing the required rotational speed. The formation radii of the waves were smaller than those observed on a smooth disk. Disks with grooves consistently demonstrated superior mixing performance, and the segregation index (X_S) decreased with the increasing number of grooves. At high flow rates, greater depths and larger angles resulted in lower X_S. Mixing times were on the order of 10^–4–10^–3 s for specific energy dissipation rate ranging from 6 to 1.43 × 10³ W/kg, and these times gradually decreased with the increasing of number and angle of grooves. According to the power law, the mixing time was scaled with dissipation with exponents ranging from −0.221 to −0.291, approximately half of those for the Kolmogorov time scale. Notably, rectangular grooves with a depth of 0.5 mm exhibited the best mixing behaviour, with the mixing time being primarily determined by τ_k^0.56.