| The structure of the intake port of diesel engine is an important factor to affect the amount and the strength swirl of fresh air in cylinder, has direct influence on the air fuel mixing and combustion. So it affects the power, economic performance and the emissions. The steady flow test and the CFD 3D numerical simulation were employed to study the helical intake port of a diesel engine in this paper. The main content are as following:The technology of reverse engineering was applied to acquire the model date of helical intake port of the diesel engine. And the 3D geometric solid model of the port was built by Pro/E. Then the numerical simulation of the flow field in port-valve-cylinder under the condition of steady testing was done by 3D CFD software. By optimizing grid quality, choosing suitable turbulence model and cliff treatment, the results between simulation test and steady flow test had good agreement. It guaranteed the correctness of the simulation.After simulation was verified, field distribution of the flow field in port was analyzed. It provided theoretical basis and guidance to optimize the structure of port. The flow information of the port provided by CFD was used to analyze how the flow coefficient and the swirl ratio vary with different valve lift in this paper.The port performances with different structure parameters were studied. With the help of flow characteristic and information provided by CFD, a modification plan by adjusting the position of the connection between guiding tube and spiral to further improve flow coefficient, was put forward. The result of simulation tests of modification plan showed that: the flow coefficient of modified model has been improved by 7.3%.The methods of steady flow test and CFD numerical simulation were used to study the helical intake port of a diesel engine, provided a fast way for optimization and design of the port in this paper. They are also could be used in other intake port design process. |
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