Optimization Of Intake Port Of Diesel Engine Through Top-down Design Method Based On The Transient Flow Simulation In Cylinder

Intake system is a very important part of diesel engine, and its performance directlyhave an influence on the air inflow and the flow state in cylinder,in turn, affects thepower performance and fuel economy of diesel engine.Based on a four-valve diesel engine inlet as the main research object, this articleexplores the influence of the main structure parameters of the swirl airway on the flowstate in cylinder. The main contents are as follows:On the base of reading a great deal of literature related in intake and exhaust systemof Chinese and foreign, we know that the Chinese and foreign scholars are doing workmethods and procedures, and the research ideas and methods of this paper isdetermined.Then the diesel helical inlet with different structure parameters were drew byusing the software UG, and the physical model of cylinder, port were completed in UG.At last, the steady calculation model and transient calculation model were assembled.Thesteady-state numerical simulation of the different models under different valve lift wasmade in FIRE. By obtaining the traces and the flow information in cylinder, the dischargecoefficient and the swirl ratio of different valve lift were calculated.And then, the transient calculation of airway-valve-cylinder model was made. Wegot the port and in-cylinder flow state of different crank shaft angle, and calculated theaverage discharge coefficient and the swirl ratio of the cylinder. The influence ofdifferent swirl intake port structure on average discharge coefficient and the swirl ratio ofthe cylinder were analyzed and the optimization scheme is put forward.The study stated that the structural parameters of swirl intake port had differentdegrees of influence on the flow in-cylinder, providing basis for the optimal solution ofintake port. But there were still a lot of work to be improved.