Influence of scale on flow and cavitation characteristics of vortex-based hydrodynamic cavitation devices

• Developed and validated CFD models for simulating flow and cavitation characteristics of vortex-based cavitation devices (VD) • Computationally investigated influence of scale-up (flow rate from ∼10 0 LPM to ∼10 3 LPM) on flow and cavitation characteristics. • Developed correlations for pressure drop, inception and extent of cavitation across wide range of operating conditions and scales. • Presented results are useful to estimate key cavitation characteristics in the cavitation zone. Vortex-based hydrodynamic cavitation devices (VDs) are widely used in water treatment, biomass pretreatment, emulsification, and crystallization, yet the effect of scale on flow and cavitation characteristics remains unclear. This work investigates geometrically similar scale-up using a validated turbulence and cavitation modelling framework over a wide range of throat diameters ( d t ) and velocities ( v t ), spanning nearly three orders of magnitude in flow rate (∼10 0 –10 3 LPM). Correlations were developed for key parameters, including Euler number (Eu), swirl ratio (ratio of the maximum tangential velocity, v θ , m a x and v t ), Reynolds number ( Re ), and vapor volume ( V vap ). Results show that Eu varies linearly with the square of the swirl ratio, and a correlation is proposed to estimate swirl ratio as a function of d t and Re . With increasing scale, cavitation extent (ratio of generated vapour volume and the device volume) and specific energy dissipation rate decrease even at constant energy consumption per unit mass, indicating reduced device performance. Scale-up also affects cavitation-zone parameters such as volume-averaged pressure, pressure fluctuation amplitude, and turbulence frequency, for which predictive correlations are developed. The approach and the presented results provide a quantitative basis for the design and scale-up of hydrodynamic cavitation devices.