The Optimization Research On Ventilation System Based On The CFD Analysis Of Closed Engine Room

Currently, the world’s shipbuilding industry has entered a higher level called "digital"stage, but the design of the engine room ventilation system was based on experience andhad not an accurate method or a mature theory. The effect of ventilation could not beknown until the ship construction was completed, and the temperature, pressure and flowrate at every point in the engine room could not be known. The distribution of the cabintemperature and flow field was very complex because it was influenced by many factors(Such as cabin structure, amount of wind, vents, etc). In addition, the closed cabinventilation system was much more complex to traditional open cabin ventilation system.So, it was not scientific to design the program of ventilation just based on experience, andwould lead to great deviation, a lot of rework and waste, more seriously affected thequality of the whole shipIf we can pre-determine the effect of the closed cabin ventilation system and find outthe problems of airflow organization and temperature distribution before the shipconstruction, it will have very important realistic meaning. In this paper, the computationalfluid dynamics (CFD) technology was used to research the typical distribution of the air inthe closed engine room and the optimization method of the closed cabin ventilation systemwas discussed.Firstly, ventilation rate and the preliminary ventilation plan were identified accordingto the requirements and specifications of the closed engine room ventilation system andthe layout plan of the system was drawn. And then the three-dimensional numerical modelof the cabin was established and the steady three-dimensional turbulence in the systemwas simulated based on CFD with the commercial CFD software FLUENT. The existingproblem in the preliminary plan was solved through analyzing the temperature and flowfield.To the improved system, related parameters that affect the ventilation effect wereanalyzed, such as the air applying angle and the wind speed. The thermal layer was drawnunder different conditions. Different index like EDT，ADPI，Et was used to evaluate theairflow. The studies have shown that, increasing vents at the location where large cabinequipments centralized can take away a lot of heat and eliminate the accumulation ofwaste gas effectively, taking into account the comfort requirements and flow organization, it is a good airflow pattern that supplying the air with moderate speed at a45-degree or75-degree angle, and returning the air from the bottom of back and side. Based on theabove research, some reasonable proposals were given to the design of the closedventilation system, and it provided a useful reference for the future design and research.