| The smoothness and stability of the air flow environment in the sun deck of a large cruise ship will provide passengers with a pleasant environment for sightseeing and recreational activities.Under the action of high pressure whirling airflow and the suction of building passage.Exhaust smoke from the cruise chimney may be floating in the stern sightseeing deck area.The smoke enters the cabin personnel access channel and the ventilation air inlet pipe under the action of the airflow.There are not only causes the extremely harmful pollution effect to the cruise ship,but also causes the extreme discomfort and the poisonous side effect to the passenger who sightseeing and entertainment in the deck area.The smoke flow field(flue gas diffusion characteristics)in the sun deck area is an important quality indicator that reflects and measures the comfort and environmental protection of large cruise ships.Based on the above reasons,based on the theory of computational fluid dynamics and the principle of smoke diffusion,a numerical study on the smoke flow field of a large cruise ship was conducted.Combining with the numerical simulation method for ship deck air distribution,the distribution characteristics of the smoke flow field in the trailing deck area were studied with different yaw angles and speed ratios.The influence of four types of double chimney arrangement on the smoke diffusion was analyzed.Achieved the diffusion of smoke from large cruise ships and the preferred arrangement of chimneys.By increasing the height of the chimney,the influence of unfavorable yaw angle and arrangement of the chimney on the diffusion of smoke is eliminated.The main research content is as follows:1.This paper expounds the development status of global large cruise ships and the development prospect of China's large cruise ships,and the background and significance of the research on the diffusion of large-scale cruise gas smoke,the research status of domestic deck gas flow field;and the research status of foreign smoke diffusion.2.The calculation flow and basic theory of Computational Fluid Dynamics(CFD)are briefly introduced,and several common turbulence models and mesh division methods are compared.The turbulence model used in this paper and the division of the computational domain by the hybrid mesh are determined,and the initial conditions are established and boundary conditions.3.Through the analysis and comparison,this paper defines the research method of the ship chimney as a cylinder flow,and the causes of the smoke washing phenomenon.Three key factors affecting the diffusion of the flue gas are summarized: turbulence area,velocity ratio,yaw At the same time,it also provides a theoretical basis for the numerical simulation of smoke diffusion in the trail deck area.4.A three-dimensional geometric model of large cruise ships is established,in which the computational domain is divided into two regions,the domain is divided into six-body structure grids,and the ICEM meshes are divided into tetrahedron-unstructured grids,which can reduce the difficulty of grid partitioning,reduce the number of grids and save computation time.CFD fluid software Fluent is used to simulate the smoke diffusion of ship chimney under 28 kinds of working conditions,and the results are visualized,and the influence of yaw angle and velocity ratio on the smoke diffusion characteristics of ship chimney is obtained.5.A numerical simulation study was conducted on the number of double chimneys in a large cruise ship.The yaw angles of 0°,30° and 4 velocity ratios were used to study the diffusion of smoke in the trailing deck area under 32 conditions of the double chimney horizontal and vertical arrangement.Numerical simulations were conducted to discuss the effect of chimney spacing on the diffusion of flue gas,and to compare the effect of chimneys on the diffusion characteristics of smoke in the horizontal and vertical arrangement. |
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