Thermo-fluid characteristics and lock-on range efficiency of infrared suppression (IRS) devices with diathermic funnels in the presence of surface radiation: A comparative study

Abstract

This investigation examines the influence of surface radiation on the thermo-fluid characteristics of three distinct infrared suppression (IRS) mechanisms employing diathermic funnels. Managing the flow and heat transfer attributes within an IRS apparatus becomes increasingly intricate owing to the convergence of frigid ambient mass entering via inter-funnel apertures and the high-temperature flue gas generated by the turbine on naval or cargo vessels. Conducting a three-dimensional analysis involving conical, louvered conical, and louvered cylindrical funnels, computational simulations based on the Navier-Stokes equation, encompassing the energy and radiative transfer equations, are conducted. This study offers a comprehensive elucidation of how the Reynolds number (ranging from 6.1 × 105 to 3.18 × 106), FOL (negative, zero, and positive), and NOL collectively influence the temperature variations at the system’s exit. Louvered cylinder-shaped funnels, specifically in zero-overlap scenarios, emerge as the optimal configuration for the IRS system. The computations undertaken aim to gauge the ship’s lock-on range, accounting for the presence or absence of the IRS system.