The Numerical Simulation Of Internal Thermal Environment Of Marine Diesel Engine Room

Marine engine room is regarded as the heart of a ship, which is a propulsion and electric power center, it contains a large number of mechanical, electric equipment and control devices. To ensure the normal operation of such equipments and normal working condition, the environmental conditions of the engine room (temperature, humidity, air velocity, cleanliness and air components, etc.) must reach a certain standard. In practice, ships are usually equipped with mechanical ventilation system to ensure those conditions to meet the requirements of the relative regulations. This paper takes a ro-ro passenger ship with 1800 meters lane as research object, and focuses on the three-dimensional airflow in its engine room. With the aid of software FLUENT, this paper simulated the flow and temperature fields in the engine room and presented the optimized design scheme of ventilation system. The main contents of this paper are as follows:Firstly, it reviewed the relative basic theories about CFD, numerical heat transfer and numerical simulation of large space buildings and then set up computational model of engine room. Secondly, it established the detailed calculation model of a certain ship. The work is divided into two parts:one is to determine air consumption and heat transfer conditions of all equipments which are used to define the boundary conditions; the other is to establish three-dimensional model of the engine room using a 3-D modeling software and divided grids to form the computing model. Fluent was selected to numerically simulate the thermal climate in the engine room and the predictions are analyzed to find out unreasonably high temperature zones and the causes. The simulated results are also compared with field measurements, and it shows that the computational model is correct. In order to make the distribution of temperature fields in the engine room more reasonable, the original engine room ventilation model is modified by changing some parameters of the air ducts(such as position and angles, etc.) and obtained the optimized design scheme of ventilation system.Finally, a summary is given and some problems to be further studied are discussed.