Multiphysics study of the water injection noise reduction system at the launch pad

Abstract

A multiphysics coupled CFD/CAA model is established for the water injection noise reduction system of China’s first universal liquid propellant launch pad, integrating fluid dynamics, heat transfer, phase change, and aeroacoustics. The SST k-ω turbulence model, Eulerian–Lagrangian droplet tracking with two-way momentum/heat/mass coupling, hybrid RANS/LES, and FW-H acoustic analogy (porous surface enclosing jet plume and flame deflector) are employed. Results show fan‑shaped water curtains (SMD ≈320 μm, secondary coverage 120°, primary mist in deflector); secondary injection reduces overall sound pressure level by 11.6 dB and gas temperature by 52%, with flow rate deviation <5% and droplet morphology matching high‑speed camera observations. This multiphysics study reveals the coupled flow‑thermal‑acoustic characteristics and provides a reference for optimal design and engineering evaluation.