Unsteady modeling of turbochargers for automotive applications by means of a quasi-3D approach

In this work a quasi3D approach has been developed and applied to the fluid dynamic simulation of turbocharging devices for internal combustion engines. The 3Dcell is based on a pseudo-staggered leapfrog method applied to the governing equation to a 1D problem arbitrarily oriented in space. The system of equations is solved referring to the relative system in the rotating zone, whereas it has been used the absolute reference system elsewhere. The vaneless diffuser has been modelled resorting to the conservation of the angular momentum of the flow stream in the tangential direction, combined with the solution of the momentum equation in the radial direction. Source terms due to the presence of the centrifugal force field and its potential have been included both in the energy and momentum conservation equations to account for the interaction of the fluid with the moving blades. The model has been validated against measurements carried out on the test bench of the University of Genoa both in diabatic and adiabatic conditions.