Proceedings in Manufacturing Systems, Volume 11, Issue 2, 2016, 71‒76 ISSN 2067-9238 OPTIMIZATION OF AN INTAKE SYSTEM USING CFD NUMERICAL SIMULATION Frantisek SEDLACEK 1,* , Michal SKOVAJSA 2 1, 2) Eng., Faculty of Mechanical Engineering, University of West Bohemia, Pilsen, Czech Republic Abstract: The paper deals with the use of CFD numerical simulations during the design and optimization of components, which are used for air distribution taking into account temperature. An intake manifold for a light racing vehicle has been chosen as a representative example. The aim of the research is to find a solution with the best possible distribution of air to the individual cylinders of the engine, whilst ensuring the quick response of the car engine. This type of analysis is very problematic because there is high speed compressible flow of air in the intake system, pressure drops and changes of temperatures. The optimization of the shape of the airbox is achieced in connection with CFD simulation (solver Siemens NX Advanced Flow) with the geometrical optimization of the generic model of the airbox. A 1D model of the engine was created to obtain the input data for CFD analysis. Values of pressures and temperatures for the individual cylinders of the engine in relation to time were subsequently generated from the 1D model. These values are used as input for the CFD analysis. The final analysis was performed as transient for several combustion cycles of the engine. Key words: numerical simulation, CFD, intake manifold 1. INTRODUCTION 1 The paper deals with the use of Computational Fluid Dynamics (CFD) numerical simulations during the design and optimization of components, which are used for air distribution. An intake manifold for a light racing vehicle has been chosen as a representative example. More precisely, a design was selected with optimization of the airbox for single seat race car of category Formula Student. The goal of this work is to find the most appropriate design of the airbox using CFD numerical analyses. The intake manifold (in slang also "airbox") is the component of an engine that supplies a mixture of air and fuel (or just air in a direct injection engine) to the cylinders of the engine. The design and optimization using CFD numerical simulation is very problematic for a Formula Student car, because this category of cars can use only a single throttle with an air intake restrictor with 20 mm diameter. For this reason, there is very high speed of the air and pressure drops in the airbox. At the beginning it was necessary to determine the process of the design and optimization of the airbox. It is very problematic to obtain the necessary input parameters for CFD analysis, because it is not possible to use a stationary type numerical analysis. The 1D model of the intake and exhaust system of the engine was created for these reasons. The 1D model of the engine was done in Lotus Engine Simulation software. Furthermore, in that software will be found the most suitable basic parameters of the airbox (such as the * Corresponding author: Univerzitni 8, Pilsen 306 14, Czech Republic, E-mail fsedlace@kks.zcu.cz (F. Sedlacek), skovi@kks.zcu.cz (M. Skovajsa) lengths of the resonance pipes, total volume of the airbox, etc.). Subsequently, the values of the air pressure in the outlets of the airbox will be generated based on this software. These values will be used as input parameters for CFD numerical simulation. The CFD numerical simulation will be combined with geometric optimization to ensure the best final shape of the airbox. The designed process can be seen in Fig. 1. Fig. 1. Flowchart of the design and an optimization process.