The SJ variable-section folded blade impeller is an axial flow impeller. At low speeds, it exhibits horizontal circumferential flow and axial flow, while at high speeds, it exhibits radial flow and axial flow. Due to the changes in the blade cross-section, there are significant variations in the discharge flow rate at different points. The small impeller, which is oriented opposite to the main impeller's inclination, enhances the vortex at the blade tip, resulting in better mixing performance. It is generally used in combination with multi-layer impellers and is suitable for unit operations such as mixing, dissolving, solid suspension, crystallization, and heat transfer of non-homogeneous phases.