Characteristic Analysis Of Spraying And Cooling Engine Exhaust System

During the operation of a ship engine,a large amount of high-temperature exhaust gas is discharged,which leads to the high infrared radiation characteristic of the exhaust system and seriously affects the stealth performance of the ship.At present,the gas blending cooling method is generally adopted to cool the exhaust system,but this cooling method greatly increases the volume and flow resistance of the exhaust system.Spray cooling method is the use of water in the evaporation of high latent heat of vaporization to reduce the exhaust system temperature,a substantial increase in heat transfer efficiency,greatly reduced the size of the cooling device,which makes the water cooling method gradually received attention.However,due to the extremely complicated phase transition process involved in the spray cooling method,the research on this method is not yet mature at present.In this paper,diesel engine power plant exhaust system,the use of cooling water spray cooling method,from the basic research,the impact of factors and experimental verification of three aspects,the exhaust characteristics of the diesel engine cooling system.Diesel engine exhaust system water cooling basic research focus on the nozzle atomization performance and gas-liquid two-phase cooling mechanism.The paper analyzes the application of spray atomization cooling method in marine diesel engine exhaust system.Based on the gas component model,the drag model and the particle wall model are introduced.The numerical simulation method is carried out according to the actual situation Fixed.According to the characteristics of the ship exhaust system,the paper selects the spiral nozzle for atomization,and analyzes the influencing factors of the spiral nozzle and the specific arrangement of the nozzle.By using the finite element model of the spiral nozzle and the numerical simulation method,the influencing factors of the nozzle atomization effect were studied respectively.Based on the piping structure and operating parameters of a diesel engine exhaust system,the Eulerian-Lagrange simulation method is used to simulate the cooling process of diesel exhaust system.The influence of water flow rate,atomization angle and cooling water temperature on the pressure field and temperature field in the exhaust system of diesel engine was studied.And various influencing characteristics were studied and analyzed.The experimental verification method is used to verify the theoretical research and numerical analysis.In this paper,the numerical requirements and stability requirements of temperature,flow and pressure in gas source simulation are synthetically considered.The experimental bench of water cooling and cooling in exhaust system is set up to simulate the cooling process of diesel exhaust system.Full consideration of the accuracy of temperature measuring instrument susceptible to water mist interference on the structure of the improvement;the use of improved measuring instruments,water cooling analog pipeline temperature measurement and pressure measurement.It verifies the influence of water atomization and cooling on the flow field inside the exhaust pipe.