Study On Performance Of Engine Gas Intake System

Gas intake system is the most important part of engine, whose performance directly influences the engine's, even automobile performance. So designing intake system with high volumetric efficiency and low noise is the aim of motor-dom is pursing.In this paper, firstly head loss and steady-state flow simulation based on finite volume theory in intake system is carried out. And, according the result, what caused head loss is studied. Then pressure wave's formation and influence on volumetric efficiency is introduced. By engine intake procedure cycle simulation, wave action and intake performance in a three-cylinder engine are analyzed. And the relationship is studied between the structure parameters and wave action, and between the structure parameters and volumetric efficiency. That is: (1) the harmonic frequency is in inverse proportion to the length of tuning duct ;(2)enlarging the diameter of tuning duct brings the increase of harmonic frequency;(3) the harmonic frequency is increasing when the length of air intake branch is shortening;(4) decreasing the volume of plenum can increase the amplitude of pressure wave. In addition, formation and development of eddy flow and distribution of air flow organization are also discussed in this paper.Secondly, an intake muffler is designed on the Helmholtz resonance theory for JL368 engine. Then it is proved the noise of the engine is reduced successfully. But power loss is changing clearly in some engine speed. So, further research is carried out on the influence brought by intake muffler assembly. The result of research is: influence caused intake muffler is small, and the increase of length of tuning duct is the prime reason.By study on the performance of intake system, flow field and aerodynamic phenomenon intake system are studied preliminarily through 3D simulation, induction is reduced successfully on the Helmholtz resonance theory, and helpful conclusions on performance of intake system are drawn. All the work and conclusion in this paper are helpful and useful to the study on enhancing the performance of intake system.