Research On Simulation And Trajectory Prediction Of Ship Exhaust Plume Diffusion

Ship exhaust contains pollutants such as carbon dioxide,nitrogen oxides,sulfur oxides and particulate matter.With the development of international shipping,the hazards caused by ship exhaust are becoming more and more serious.Countries have introduced stricter regulations and established emission control areas to limit the emission of ship exhaust.However,the trajectory of exhaust gas is difficult to predict,making it difficult to carry out remote detection of discharged pollutants.In view of the above problems,this paper takes ocean-going cargo ships as the research object,carries out the research on the diffusion of ship exhaust,clarifies the diffusion law of ship exhaust plume,and develops the plume trajectory prediction software.The main work content of this paper is as follows:(1)According to the existing literature,the numerical model of ship exhaust plume diffusion is verified.A ship exhaust plume diffusion simulation model was established,the plume diffusion law in a calm wind environment was analyzed,and the influence of three factors,exhaust temperature,exhaust velocity,and chimney angle on the exhaust gas diffusion in a calm wind environment,was studied.The study found that the diffusion of the plume is mainly divided into two stages,separated by the second extreme velocity point,and there is an obvious boundary between the plume and the air during the diffusion process.The chimney angle has a great influence on the early diffusion of exhaust gas,but basically has no effect on the diffusion rate of exhaust gas;the influence of exhaust gas velocity on the early stage is mainly in the early stage;the temperature change of exhaust gas does not have much difference on the early stage of exhaust gas diffusion.The influence of exhaust velocity on exhaust diffusion is closely related to its direction,so exhaust velocity and chimney angle can be considered jointly.(2)Carried out research on the diffusion law of exhaust gas in a windy environment,carried out research on the influence of four factors of the same speed ratio,yaw angle,exhaust temperature,and chimney angle on the plume diffusion in a windy environment under different wind speeds,and The diffusion law of particulate matter in low temperature environment was studied.The research found that the turbulent area behind the ship has a great influence on the diffusion of exhaust gas,which will cause the stagnation and extrusion of the exhaust gas;according to the degree of influence of the exhaust gas on the turbulent area,the diffusion of smoke in a windy environment can be divided into two types: the early stage and the late stage.state.It is found that both the synthetic wind speed will affect the stability of the exhaust gas diffusion trajectory.Larger,the slower the exhaust temperature drops.At the same time,it is found that the diffusion law of particulate matter is similar to that of exhaust gas.Other factors had little effect on the capture rate of particulate matter,but when the synthetic wind appeared yaw angle,the capture rate of particulate matter in the interval increased rapidly with the increase of yaw angle.(3)The influence of various factors on the plume diffusion rate was studied,and the construction of the prediction software for predicting the ship exhaust plume was carried out.The research found that the most positive factor is the exhaust gas velocity,the most negative factor is the external flow velocity,and the least influential factor is the exhaust gas temperature.The GBDT model is chosen as the prediction algorithm.After error analysis,it is found that there are large errors in the prediction model,but the predicted trajectory trend is consistent with the calculated value,which has reference value.