Simulação de escoamento em câmara de combustão compacta para MACI

Abstract

In this work, a compact combustion chamber was simulated with valve and duct geometry to obtain tumble flow at the intake. The compact geometry provides for the intake valves to be positioned vertically to the side of the cylinder, with the discharge valves positioned opposite to them in the combustion chamber. The final combustion chamber was left with a maximum height of 13mm and with a distance between the heads of the intake and discharge valves of 11mm when fully closed. The combustion chambre volume used was 53.2cm3 for a direct qualitative comparison with the AP 1.6 gasoline engine, with 8.5:1 compression ratio, whose flow bench flow data are found in the bibliography. The tests were performed from the drawings made in CAD software and the simulations by means of CFD software for a pressure difference of 10 inches of water column, simulating a flow bench test. The simulations were performed with the intake valve lift divided into 5 positions with equidistant interval between them, always obtaining higher flow rate than the original cylinder head. For the maximum lift of 7mm an increase of 19.67% of the valve intake area was obtained with a flow rate increase of 51.57%. For the maximum lift of 9.3mm, the area is 64.73% larger with an increase in flow of 64.14% compared to the original cylinder head. It should be noted that this improvement isqualitative, due to the Alternative Internal Combustion Engine (ICE) having pulsed flow and the flow bench having continuous flow. Thus, there was an increase in volumetricefficiency, although it is not proportional to the increase in flow rate of the tests performed.