New Correlations for Flow and Conjugate Heat Transfer With Surface Radiation Characteristics of a Real-Scale Infrared Suppression System With Conical Funnels

Abstract

The consistent and accurate prediction of fluid flow and heat transfer characteristics in an infrared suppression (IRS) device is challenging due to the complex nature of the flow features. The cool ambient air intake and subsequent mixing of hot exhaust gas from the engine in the cargo/naval ships are done inside the IRS system. The objective is to propose correlations for mass entrainment and outlet temperature for the IRS device with conical funnels. The mass intake rate and funnel exit temperature are determined by a set of relevant operating and geometric parameters, such as Reynolds number, nozzle exhaust temperature, the number of funnels, and funnel overlap. In this study, the funnel walls are conducting with finite wall thickness, and the surface radiation is taken into consideration. Numerical simulations are performed for the real-scale IRS unit by solving the mass, momentum, energy, and radiation equations in the computational domain surrounding the system. Nonlinear regression analysis of the data is carried out using the Levenberg and Marquest (L–M) method to achieve an empirical correlation of mass intake ratio and outlet temperature ratio. The proposed correlation for mass intake ratio is valid within ±6%, and that of outlet temperature is valid within ±5% of the numerical data. The valid ranges for correlations are 6×105≤ nozzle Reynolds number ≤3×106; 2 ≤ number of funnel ≤ 5; −0.325 ≤ funnel-overlapping height ≤ 0.25; and 1.33 ≤ nozzle exit temperature ≤ 2.