Steady Flow Test And Numerical Simulation Of Air Flow In Double Intake Ports For4-Valve Diesel Engine

Experiments of the different kinds of intake port--Single helical intake port, single tangential intake port, combination intake port of4D24four-valve diesel engine had been done at the steady flow test rig. The test results show that the swirl ratio in the small valve lift is larger, which is very different from the flow characteristics of the usual diesel engine inlet. It is caused by the spiral segment of the edge of the valve.The three-dimensional solid model of port-valve-cylinder had been built by Pro/E, which included Single helical intake port, single tangential intake port, combination intake port. High-quality computational grid is generated by unstructured grid method in Fire.A three-dimensional numerical simulation of mathematical model was created. The SIMPLE method was used to simulate the steady flow of the internal gas. After setting the discrete solution and boundary conditions, initial conditions of partial differential equations, with repeated testing and trial, the three-dimensional steady flow numerical simulation of the port-valve-cylinder intake process of the three intake ports were finished, which has been verified the level and accuracy of the prediction of the mathematical model. It also confirmed that the three-dimensional numerical simulation was reliable and effective.It is found that the simulation results are in good agreement with the experimental results after analyzing the velocity distribution, pressure distribution, turbulent kinetic energy distribution, flow lines and traces, swirl ratio, flow coefficient and other flow structure. It is also availability to get a large number of flow of information, by which the effect of the geometry to the flow characteristics can be in-depth intuitive understand. The maximum gas flow rate of combined port took place in the vicinity of the intake valve. Between the two intake valves at the bottom of the cylinder head and was interference area, where a strong exchange between moment of quality and moment of momentum caused the loss of moment of momentum. The impact mechanism of the spiral segment of the edge of the valve. which effected eddy size during a small valve lift was understood.By changing "the spiral segment of the edge of the valve" structure layout, simulate and calculate the flow coefficient and swirl ratio of combination intake port under the "cancel the spiral segment" condition. Comparison of test results with the original intake port model, it shows that" the spiral segment of the edge of the valve" results in the small valve lift is very obvious.Test and research results show that it is currently the best development and design methods of intake port by using the method of CFD as the foundation and combining with the steady flow test. It can be very deep, visually reveal mat the relationship between structure parameters of the port valve, cylinder and the form, flow characteristics of the flow field.