Experimental and numerical analysis of discharge coefficient in internal combustion engine

Abstract

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.In order to improve the breathing capacity of the intake system, experimental and numerical investigations of discharge coefficient (CD) are performed in an internal combustion engine. For this paper an experimental test rig was developed to measure steady and transient flow. Steady experimental data was obtained for various valve lift and transient measurement with only the intake valve operating. The suction pressure was generated by a fan, and utilized as boundary condition for the numerical simulation. The air mass flow was measured with a commercial hot film anemometer sensor with appropriate time response. The angular position of the camshaft was measured with a rotary encoder with a resolution of 0.175 degree. A length gauge with an accuracy of ± 0.2 μm was used to measure valve opening. The air mass sensor and the rotary encoder were connected to a data acquisition board (National Instruments 6221) and its original LabVIEW software. The numerical simulation uses the STAR-CCM+ commercial Finite Volumes CFD code. Regarding turbulence, computations were performed with Reynolds-Averaged Navier-Stokes Realizable Two-Layer k-ɛ model with hybrid treatment near the walls. A detailed mesh independence study was performed. The steady simulations were done for the same experimental valve lift, with a good agreement among results.