109 Sustainable Maritime Transportation and Exploitation of Sea Resources – Rizzuto & Guedes Soares (eds) © 2012 Taylor & Francis Group, London, ISBN 978-0-415-62081-9 A numerical investigation of exhaust smoke-superstructure interaction on a naval ship S. Ergin, Y. Paralı & E. Dobrucalı Istanbul Technical University, Department of Naval Architecture and Marine Engineering, Maslak, Istanbul, Turkey ABSTRACT: The exhaust smoke-superstructure interaction for a generic frigate is investigated numerically. The frigate was driven by a CODOG system. The k-ε model is adopted for turbulent closure, and the governing equations in three dimensions are solved using a finite volume technique. The compu- tations were performed for different yaw angles, efflux velocities and temperatures of the exhaust smoke. The cases with diesel engines and gas turbines are considered. The calculated streamlines, temperature contours and smoke concentrations are presented and discussed. Furthermore, the detailed predictions are compared with the available experimental measurements. A good agreement between the predictions and experiments is obtained. The study has demonstrated that computational fluid dynamics is a power- ful tool to study the problem of exhaust smoke–superstructure interaction on ships. of exhaust smoke dispersion from the ship stacks is extremely complicated task. Recently, a com- prehensive review on the numerical modeling of exhaust smoke dispersion from ships is given by Kulkarni et al. (2011) and Mishra et al. (2010). Tra- ditionally, the exhaust smoke dispersion has been investigated using scale models in wind tunnel (see, for example, Nolan 1946, Acker 1952, Isyunov et al., 1979 & Kulkarni et al., 2005). However, these experimental studies are expensive, lengthy and time consuming. In this paper, the exhaust smoke dispersion from a generic frigate and its interaction with rest of the superstructure are investigated numerically. The perspective view of the frigate model is shown in Figure 1. The frigate is driven by a combined diesel or gas turbine, CODOG system. The k-ε model is adopted for turbulent closure, and the 1 INTRODUCTION Nowadays, the understanding of the exhaust behavior of ship stacks has become quite impor- tant in the naval ship design due to advances in superstructure electronics (radar and antenna) and heat seeking missiles. The predictions of veloc- ity and temperature fields of the ship exhaust plume from the stack are of vital importance for positioning and arranging of various superstruc- ture electronics, weapons, gas turbine intake and ventilation intakes in the superstructure with the minimum interference with the hot exhaust smoke from the stack. However, all modern naval ships tend to favor short stacks and tall mast to house electronics. This makes them prone to the prob- lem of smoke nuisance where hot exhaust gas gets entrapped into turbulent wake of the superstruc- ture and deteriorates the performance of electron- ics, weapons, sensors, increase the ships infrared signature and hampers the internal ventilation and gas turbine intakes. This is also problem for the operation of helicopters from ships (see, for exam- ple, Park et al., 2011, Mishra et al., 2010, Ergin et al., 2010, Syms 2008, Kulkarni et al., 2005, 2007, Fitzgerald, 1986). The dispersion of exhaust smoke is affected by a large number of parameters such as efflux velocity and temperature of smoke, level of turbulence, wind velocity and direction, geometry of the structures on ship’s deck etc. (see for example, Baham et al., 1977; Fitzgerald, 1986, Jin et al., 2001, Park et al., 2011, Heywood, 1988). Therefore, the prediction Figure 1. Perspective view of the frigate model.