Research Of Exhaust Outlet Resistance Coefficient Of High Speed Passenger Train

With the rapid development of social economy and the continuous improvement ofpeople’s living standard，China’s high-speed rail network is developing rapidly in recentyears，high-speed passenger train with "convenient, fast, safe and comfortable" characteristicbecome the first choice of the national travel and tourism transport. Exhaust outlet of highspeed passenger train is an important part of a ventilation system, and plays an important rolein the whole ventilation system, its performance not only directly related to the room the airquality inside, environmental comfort, the health of passenger and the economy of ventilationsystem, but also affect the fresh air into the ventilation system and exhaust gas.The exhaust outlet design has the vital significance in the high speed passenger train to theentire ventilation system, its design reasonable or not is related to the quality of the indoorenvironment. But to the exhaust outlet flow resistance performance research is an importantpart of the ventilation system in high speed passenger train.This paper has made the brief introduction to the domestic and foreign high speedpassenger train exhaust system, one of which is been chosen as the object of study of exhaustoutlet resistance coefficient. In the passenger train waste gas through the exhaust outlet is acomplex phenomenon of flow, the influence factor of flow resistance coefficient ismultitudinous, such as the fluid physical property, the object of study geometry shape，external conditions, the train speed and so on, If considered fully to the influence of all kindsof operating mode condition in theory is difficult to achieve，through experiments to study notonly very difficult to change the working conditions of the demand，and the cost is very high，so only through the numerical simulation method to study the resistance coefficient of theexhaust outlet. Therefore，by the means of CFD numerical simulation software，this paperconducts an in-depth research on exhaust outlet resistance characteristic under the summerand the winter operating mode, by simplifying the model of research object and establishingthe wind tunnel simulation system of exhaust outlet, has studied the resistance coefficient andthe characteristic of exhaust outlet of high speed passenger train when the static and therunning status. This research is based on to the standard k-ε rapids double equation modelwhich three dimensional incompressible, has analyzed the high speed passenger trainexhaust outlet resistance characteristic and the friction coefficient change situation by thefinite volume method simulation.The results show that passenger train in the static condition，the outside air temperatureis almost no effect on the resistance coefficient of the exhaust port，but it increases with therising of temperature in passenger train. In the summer and winter conditions drag coefficient decreases with the increase of the exhaust air；The train in running status and under twooperating mode conditions，when the exhaust air volume is constant, with the increase ofpassenger train speed，the exhaust outlet local resistance loss and resistance coefficientincreases, the train speed higher resistance coefficient of the increment is larger，Under certainspeed of the train，the local resistance loss of the exhaust outlet increases with the increase ofthe exhaust air flow rate，but the resistance coefficient decreases as it increases，when exhaustair is lower，there would be a relatively large increment of exhaust outlet resistancecoefficient.