Study on the Cavitation Performances and Unsteady Characteristics of a Centrifugal Fire Pump

Centrifugal fire pumps are critical for firefighting systems but suffer from cavitation and instability under off-design conditions. However, systematic analyses of their flow-rate-dependent dynamics remain limited. This study systematically investigates the hydraulic performance, cavitation characteristics, and dynamic pressure pulsations of a centrifugal fire pump under various flow conditions (50%–150% of the design flow rate) through combined numerical simulations and experiments. Steady simulations were conducted using the standard κ-ε turbulence model, while unsteady simulations were performed with a 2° angular time step to capture the transient interactions between the impeller and the volute as well as the resulting dynamic pressure pulsations. Key results revealed that: At low flow (60% Qd)， Radial force amplitudes increased by 40%, accompanied by 9.86 Hz low-frequency pulsations attributed to backflow-induced instabilities; At high flow (150% Qd), The critical cavitation number σ₃% surged to 0.961, indicating a 2.6-fold cavitation risk compared to the design condition (σ₃% = 0.376); The findings provide actionable strategies for optimizing pump design and operational stability in firefighting systems.