Influence of transient phenomena in the discharge coefficient through the intake valve in an internal combustion engine
The project of engine intake systems involves optim ization of parameters such as the pipe length and diameter, ju nctions, and opening and closing times of the intake and exhaust valves. The correct sizing leads to an increase of the air mass admitted to the cylinders at the desired engine operational con ditions. A suitable design of the intake valves in internal co mbustion engines is one of the factors that maximize the amo unt of intake air mass to the cylinder. The parameter that determ ines the maximization of the mass flow through the valves is called discharge coefficient. The mass flow through the va lve is usually described by the compressible flow equation through a restriction, based on a dimensional analysis of an isentropic flow. In the present work, pressure variations cau sed by the valve movement were investigated experimentally considering an intake system. The objective was to study and co mpare the dynamic response of the flow through the intake val ve. For this purpose, curves of mass flow rate and the dynamic p ressure in several locations of the intake system were obtaine d. The experimental data were obtained from the intake sys tem connected to a cylinder head. The cylinder head was installed in an air supply system consisted by a blower, a flow measurement device, and a reservoir chamber. The valves were driven by an electric motor with controlled rotatio nal speed. The results showed that the correct design of the i ntake valve affects positively the air mass flow rate.