| The exhaust process of the traditional two-stroke low-speed engine is to discharge the high-temperature and hot exhaust gas and DC scavenging air in the cylinder to the air collecting box during the entire duration of the exhaust valve from opening to closing.The temperature and pressure of the discharged DC scavenging air are low.After being mixed in the exhaust manifold,the thermal power of the engine exhaust airflow will decrease,which will reduce the thermal quality of the total exhaust energy,which is not conducive to the turbocharger and waste heat utilization system.Stable and efficient operation.This paper proposes a low-speed engine exhaust energy hierarchical shunt output control method,that is,the exhaust valve is opened continuously,according to the energy grade and thermodynamic parameter characteristics of different exhaust phases,the exhaust energy hierarchical shunt output control is realized,and the system load heat is used according to the waste heat.To achieve optimal matching.This method is one of the new technical means to improve the thermal efficiency of marine low-speed engines.This paper focuses on the realization of the low-speed engine exhaust energy classification method and the study of the influence law of exhaust all-phase energy parameters.Taking the 340 series two-stroke marine low-speed engine as the research object,establish one-dimensional and three-dimensional working process models,and carry out corresponding corresponding Model accuracy verification.Subsequently,the GT-Power and CONVERGE software were used to carry out joint simulations to obtain the airflow status in the complete working process under the traditional exhaust situation,which provides a basis for the research on the exhaust energy classification and split output control.In order to realize the low-speed engine exhaust energy grading and shunting,the design of the structure principle and control method of the exhaust grading and shunting device is carried out.Based on the feasible grading and shunting scheme,a variety of cascade utilization schemes for the residual energy of the marine low-speed engine based on the exhaust energy grading and shunting are proposed.One-dimensional and three-dimensional calculation models of low-speed engine exhaust energy grading and splitting are established.According to the one-dimensional and three-dimensional models of the exhaust energy classification and splitting mechanism,the exhaust energy distribution law under different exhaust phases is explored,including the change law of exhaust temperature,exhaust pressure,exhaust mass flow,etc.Combining the change law of energy parameters after the exhaust gas is divided into stages,based on the 340 series two-stroke marine low-speed engine exhaust gas collecting device,Fluent is used for CFD simulation analysis,and the high-temperature exhaust energy after the staged distribution is further studied in the gas collecting box and the total exhaust gas.For the flow in the pipe,the optimized design of the structure of the exhaust gas collecting device after the hierarchical split is carried out.By optimizing the design,changing the size of the gas collecting box and other factors,the flow energy dissipation during the flow in the gas collecting box is optimized,and the pressure before the vortex is optimized,so that the entire exhaust energy classification and splitting scheme has better feasibility,and further flow from the exhaust The angle of view provides rules for the design of hierarchical shunt system... |
