In ICEs, turbulence trends inside the cylinder is an indication of good combustion and therefore of better performances. In recent years, with the development of 4-valve-cylinder heads and of GDI engines, the creation of the tumble motion using ducts with steeper inclinations has become necessary despite the negative impact on the discharge coefficient. The project described here was developed by using the geometry of a Ducati racing car head. In particular, a commercial code CFD/3D was used to analyse the tumble motion created by an L-shaped adapter, a device which is usually used for experimental data of this phenomenon under steady state conditions. After this analysis, the standard configuration of the model, a system (tumble improver) was designed so that the intensity of the tumble vortex was increased at medium-low loads without affecting performance under full loads. Under equal outgoing air mass flow rate, the values of the tumble coefficient (Nt) were compared and calculated by using, as a load adapter, as an alternative, both the traditional throttle valve and the tumble improver. Furthermore, some problems regarding turbulence models involved in this system were investigated and the solutions adopted were analysed to obtain satisfactory results.
Design and CFD/3D numerical analysis of an intake duct with a non intrusive “tumble-improver” to increase the turbulence at medium-low loads
CAVALLETTI, MICHELE;MARIANI, Francesco
2004
Abstract
In ICEs, turbulence trends inside the cylinder is an indication of good combustion and therefore of better performances. In recent years, with the development of 4-valve-cylinder heads and of GDI engines, the creation of the tumble motion using ducts with steeper inclinations has become necessary despite the negative impact on the discharge coefficient. The project described here was developed by using the geometry of a Ducati racing car head. In particular, a commercial code CFD/3D was used to analyse the tumble motion created by an L-shaped adapter, a device which is usually used for experimental data of this phenomenon under steady state conditions. After this analysis, the standard configuration of the model, a system (tumble improver) was designed so that the intensity of the tumble vortex was increased at medium-low loads without affecting performance under full loads. Under equal outgoing air mass flow rate, the values of the tumble coefficient (Nt) were compared and calculated by using, as a load adapter, as an alternative, both the traditional throttle valve and the tumble improver. Furthermore, some problems regarding turbulence models involved in this system were investigated and the solutions adopted were analysed to obtain satisfactory results.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
