Experimental and Computational Assessment of a Converging–Diverging Funnel Arrangement System for Marine Gas Turbine Applications

Abstract A funnel arrangement system is essential in modern naval ships to cool the hot exhaust gas and suppress its infrared (IR) signature. Laboratory experiments utilizing various funnel designs, specifically converging–diverging funnels, have produced promising results regarding the infrared suppression (IRS) model. The experimental analysis varied the Reynolds number between 4020 and 16,800. At the same time, the temperature ratio was adjusted from 1.1411 to 1.2974, yielding significant insights into the relationship between mass flow dynamics and thermal efficiency in IRS devices. This study proposes a novel type of funnel arrangement system featuring a converging-diverging funnel configuration. The thermo-fluid analysis of the proposed system involves solving transport equations, including continuity, momentum, energy, and turbulence, using the finite volume solver in ANSYS FLUENT. The study aims to determine the effective geometrical parameters, such as the inlet radius, outlet radius, radial overlap, and funnel inclination angle, to optimize the system's performance. The impact of these pertinent parameters on the air entrainment and system exit temperature is elucidated here. The funnel walls are assumed diathermic for the present analysis. The results show that maximum mass entrainment and lowest outlet temperature are achieved at a radial overlap of 0.3 m. A funnel inclination angle of 4 deg shows a maximum mass entrainment.