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The paper describes a combined experimental-theoretical investigation into the intake flow produced by a port commonly used for both DI diesel and gasoline engines, namely a helical. The study consists of two major parts. Firstly, 3 orthogonal velocity components were measured under steady flow conditions within the valve gap using LDA. Data was obtained around the valve periphery and in different planes between the valve and the cylinder head. This was repeated for a number of different valve lifts. Prior to the second stage, an unsteady gas-dynamics calculation was performed to determine the thermodynamic conditions immediately upstream of the valve and the mass flow rate through the valve opening throughout the intake stroke.

Three dimensional velocity measurements of the in-cylinder aerodynamics in the steady airflow rig for two different Diesel cylinder heads were obtained by laser anemometry. Complex recirculating flows with high mean velocity gradients were found while the fluctuating component of velocity was relatively constant. Vector addition of two components in turn allowed rapid comparison to be made of the airflow characteristics between cylinder heads and and comparison with earlier hot wire and vane anemometer measurements. The directed port cylinder head was found to produce two main vortices whereas a cast helical port produced a flow which approached simple solid body rotation.