Thermal Management Research On Shunting Locomotive Engine Room Based On Field Synergy

The engine compartment cooling system is an important component of the shunting locomotive’s power system,and its operational stability is essential to ensure the normal operation of the shunting locomotive’s power system.With the further improvement of the integration of parts and components,the internal structure of the locomotive engine compartment is complex,therefore the heat dissipation of the engine compartment has also brought greater challenges,and the research on the thermal management of the engine compartment has also received extensive attention from scholars.When the engine is over-full with power and load,the heat generated by the heating components may not be quickly discharged from the engine room,which will cause the engine to reduce or stop power.Therefore,it is necessary to study the thermal management of the engine room of the shunting locomotive to improve the engine room heat exchange efficiency.This thesis has a certain significance for optimizing the thermal management research on the engine room and improving the stability of locomotive power unit operation.This thesis takes the engine compartment of a type of railway shunting locomotive as the research object.Based on the synergy theory of velocity field and temperature gradient field,the multi-objective optimization design of the nacelle structure is carried out with the aim of reducing the field synergy angle of the nacelle,improving the temperature efficiency and comprehensive heat transfer coefficient of the nacelle,improving the local high temperature phenomenon in the working environment around the components and enhancing the reliability of the power unit.On the premise of ensuring the accuracy of calculation,the components in the nacelle of the shunting locomotive are reasonably simplified,then ICEM is used to divide the mesh and the Fluent software is used to simulate and analyze the flow field in the nacelle.Four optimization parameters,i.e.the length and installation angle of the deflector,the distance between the fan and radiator,and the distance between the air intake grille and the top of the nacelle,are selected to study their effects on temperature efficiency,the integrated heat transfer coefficient and the field synergy angle.A polynomial fit using a second-order response surface model is carried out to obtain the implicit functional relationships between the temperature efficiency,integrated heat transfer coefficient and field synergy angle with respect to the four optimization parameters by ISIGHT.The second-order response surface model is solved and analyzed by a non-inferiority ranking genetic algorithm(NSGA-II)to finally obtain an optimal set of cabin structure parameters to improve the heat transfer efficiency of the cabin and reduce the engine cabin temperature.Results show that the optimized field synergy angle θ is decreased from 75.445° to71.892°,temperature efficiency f is increased by 1.425 to 1.716,the integrated strengthening heat transfer coefficient h also rose from 5.924 to 8.183,engine compartment temperature efficiency and the comprehensive heat transfer coefficient are increased by 18.182% and38.133% respectively,the comprehensive field synergy angle is decreased 3.553°,and the high temperature phenomena of engine room has been improved greatly.