Eventos Anais de eventos
ENCIT 2018
Brazilian Congress of Thermal Sciences and Engineering
NUMERICAL SIMULATION OF UNSTEADY FLOW IN ENGINE INTAKE AND EXHAUST MANIFOLDS USING THE METHOD OF CHARACTERISTICS
Submission Author:
Felipe Augusto Ferreira Gomes , SP
Co-Authors:
Felipe Augusto Ferreira Gomes, Waldyr Gallo
Presenter: Felipe Augusto Ferreira Gomes
doi://10.26678/ABCM.ENCIT2018.CIT18-0625
Abstract
The manifolds influence the engine performance and a model capable of estimating the wave action inside them is fundamental. Unsteady three-dimensional models are very expensive and time consuming. However, an one-dimensional approach has shown to be a fair approximation for the problem. There are several numerical methods of different accuracy to conduct an one-dimensional unsteady compressible flow. The method of characteristics (MOC) was one of the first methods to be applied in engine manifolds with reliable results. The method is based on the exact solution and for this reason have good response in the presence of shock waves despite of having first order precision. The volumetric efficiency and the wave behavior were analyzed for different runners length operating between 1500RPM and 4000RPM. Results showed that volumetric efficiency is heavily influenced by reflected compression waves on intake. However, on exhaust the effect is less significant. For short runners, efficiency demonstrated to have fairly stable variation across engine speed. Nevertheless, up to 30% change were detected between low and high speed for longer runners. The 0.800m intake runner and 1.000m exhaust presented better performance, with volumetric efficiency above 90% for all engine speeds.
Keywords
Intake/Exhaust manifolds, One-dimensional flow, Method of characteristics
