Flow‐regime transition and flow‐structure‐based scale‐up of Siemens reduction furnaces

Abstract Siemens furnaces are nonlinear CVD reactors in which flow regime evolves as rods grow, while clear scale‐up criteria remain lacking. In this work, flow experiments and simulations are combined to identify hydrodynamic mechanisms. Experiments show a transition from jet‐cavity to jet‐rod interaction. Simulations show that excessive nozzle density shortens the jet‐development space, promotes a confined diffusive turbulence region, whereas rod‐bundles suppress entrainment, preserve axial momentum, and localize jet transport. Two dimensionless parameters are proposed. In jet‐cavity‐dominated regime, the nozzle number should be limited, satisfying . In jet‐rod‐dominated regime, effective nozzle‐rod matching is achieved when on the order of 3–4. This work establishes a physically grounded basis for the design and hydrodynamic scale‐up of confined multi‐jet CVD reactors by linking reactor geometry with the preservation of favorable flow organization beyond empirical geometric scale‐up.