Research On Design Method Of Cylinder Center Distance Of Multi-cylinder Diesel Engine Based On Dymola

Cylinder center distance is one of the key dimensions in the conceptual design of the diesel engine,which directly affects the overall size,strength and cooling system layout of the diesel engine.At present,the relevant research on the design of the cylinder distance is still based on the empirical design method,which highly relies on the empirical design value in the design process,and only considers the influence of the design size on the dynamic system of the diesel engine.Taking into account the shortcomings of the existing cylinder center distance design method,this paper establishes a diesel engine cylinder center distance design calculation simulation model on the Dymola platform,and proposes a design method that comprehensively considers the diesel engine thermodynamic system,dynamic system and cooling water system;Based on the design parameters,the multi-layer perceptron neural network model is used to realize the prediction model of the cylinder center distance design size.Take the 6EX340 diesel engine as an example,build its single-cylinder diesel engine model and perform simulation calculations,in which the dynamic system and the in-cylinder working process are transmitted in real time through different interfaces between the in-cylinder pressure and speed,which realizes the coupled calculation between thermodynamics and dynamics;According to the layout drawing of the cooling water system of the 6EX340 diesel engine,combined with the working process in the cylinder to build the cooling water system of the whole machine,the temperature of the key positions of the cooling water system and the wall temperature of the combustion chamber components are obtained by simulation calculation,and the three-dimensional steady-state temperature field simulation is used to verify The correctness of the coupling calculation between the cooling water system and the thermodynamic system;based on the simulation of the single-cylinder engine and the cooling water system,the multi-cylinder diesel engine cylinder center distance design calculation model is established,and the 6EX340 diesel engine is used as an example to simulate different working conditions The calculation and comparison of part of the simulation results with the experimental values prove the correctness of the model.The simulation results mainly include the relevant characteristic parameters of diesel engine thermodynamics,the distribution of cooling water flow,and the output torque.Based on the design and calculation model of cylinder center distance,an evaluation method that comprehensively considers the suitability of cylinder center distance is proposed.The evaluation method mainly includes diesel engine balance analysis,crankshaft stress analysis,and crankshaft fatigue strength analysis based on model simulation.And cooling water distribution analysis;by changing the size of the cylinder center distance,the influence of the change of the cylinder center distance size on the evaluation content is analyzed,and it is found that the change of the cylinder center distance size has a small effect on the cooling water distribution,which will obviously affect the balance of the diesel engine And the force of the crankshaft.Calculate the design parameters of marine diesel engines in service,analyze the relationship between cylinder center distance and cylinder diameter and other parameters,and use the multi-layer perceptual neural network prediction model to establish a two-stroke diesel engine cylinder center distance prediction model.The prediction model of cylinder center distance performs well in overall prediction,the average percentage error(MAPE)of the prediction result is less than 2%,and the correlation coefficient reaches 0.999.The prediction result and the real value have fully approximated the linear correlation.In the diesel engine pre-design stage,a small amount of basic design parameters can be used to accurately achieve the cylinder center distance.Size prediction.