Investigation of Intake Concepts for a Formula SAE Four-Cylinder Engine Using 1D/3D (Ricardo WAVE-VECTIS) Coupled Modelling Techniques

摘要

Many variations of intake designs currently exist in Formula SAE. This paper sets out to investigate if one intake design provides improved performance over another and to gain further insight into the nature of the airflow within a Formula SAE intake. Intake designs are first classified by physical layout. Then Ricardo's software WAVE (1D) and VECTIS (3D) are used to investigate the performance of the three most common intake concepts as well as two variations of the base concepts for a naturally aspirated four-cylinder Formula SAE engine. Each intake concept is modeled across an RPM range using a WAVE simulation. Simulations are performed at three different RPM using WAVE and VECTIS coupled at the intake inlet and runner exits of each intake concept. A 3D simplified CAD geometry of each intake is used for the VECTIS part of the simulation. An unsteady flow analysis was used instead of a steady flow analysis due to the nature of the flow within an engine. Simplifying assumptions and the use of computational grid convergence analysis and the comparison of 1D and 1D/3D simulations are described. Evaluations of intake performance are also discussed. Intake performance is determined by several factors: cylinder-to-cylinder volumetric efficiency, time of choked flow in the restrictor, total pressure loss along the restrictor, sound spectrum frequency content, and physical packaging characteristics. In addition, intake manifold and restrictor interaction is discussed as well as visualization of adverse flow conditions. Packaging considerations such as the location of flow bends for minimum pressure loss are also discussed. The authors found that what they define as the Conical-Spline Intake Concept offers the best performance. This intake concept offers an order of magnitude improvement in the variation of cylinder-to-cylinder volumetric efficiency with consequent improvements in ease of tuning and acoustic noise emission control. In addition, it has the lowest total pressure drop along the diffuser of all the concepts evaluated.