Research on performance of helical intake port of diesel engine based on numerical simulation

According to the principle of high-grade internal combustion engine, the structure and performance of the spiral inlet and tangential inlet of diesel engine are simulated by using Liszt’s multi-dimensional simulation software AVL-Fire, and the corresponding flow coefficient and eddy current ratio can be obtained. At the same time, the speed vector diagram, pressure cloud map and mixed gas flow trace diagram of three different valve lifts in the airway are taken. By studying the simulation results, we can find the shortcomings in the design of the inlet, and provide a theoretical basis for the optimization of the engine intake system.

I. Overview

Looking back at the development history of diesel engine in the past years, the optimal design and matching of intake and exhaust system, fuel supply system and combustion chamber shape have a great impact on the combustion of mixture. In the process of the evaluation and design of the intake port of diesel engine, the method that people are good at using is to do the test in the steady flow test-bed, design according to experience, and then repeat the test, and finally get the model that meets the requirements. However, the cost of this method is very high and needs a lot of capital investment. Reset with the emergence of high-speed computer, computer numerical simulation technology has brought hope to people. CFD technology can reduce a lot of time and manpower^[1–2]. People who are familiar with CFD process draw a model and then simulate it. It does not need a long time and does not need to consider the interference of external conditions, which is more conducive to optimize the comprehensive performance of diesel engine. Based on the original intake port model of diesel engine, using the special multi-dimensional numerical simulation software AVL fire and referring to the evaluation standard of intake and exhaust of related models, the flow field of spiral inlet with different valve lift is analyzed and calculated, and the relevant calculation model for evaluating the steady flow characteristics of intake port is established. The inlet flow distribution parameters, in cylinder pressure and velocity analysis of different valve lift, flow coefficient and swirl ratio are given.