Optimization thermal performance of ship infrared suppression devices via dual-layer water mist cooling

To enhance the performance of conventional infrared suppression systems, this study proposes a dual-layer spray system that leverages staggered water mist coverage to enhance the synergy between water mist cooling and airflow entrainment, significantly improving IRS performance. Using computational fluid dynamics (CFD), key parameters including the radial distance of spray injectors from the centerline (l_n), axial spacing between layers (d_n), and horizontal angular offset (φ) were systematically optimized. The results indicate that optimizing l_n to 0.8 m significantly enhances droplet dispersion while minimizing kinetic energy loss, thereby improving exhaust cooling efficiency. When d_n is 100 mm and φ to 30°, the system achieves optimal performance, reducing the outlet temperature of the mixing diffuser by up to 82.48 K, and effectively controlling the wall-temperature rise caused by airflow compression. Furthermore, this study reveals that momentum exchange between entrained airflow and water mist may cause high-temperature fluid to impact the wall, increasing local wall-temperature. The study provides an effective strategy to balance exhaust cooling and wall-temperature control, advancing IRS technology for naval applications.