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Typical automotive engine-cooling fan assemblies include an electric motor having a driveshaft coupled to a fan. The typical fan includes a hub, which extends from the driveshaft to the root of the fan blades. Radial ribs are incorporated within the hub to stiffen the fan structure. The fan hub including the ribs pulls cooling air through the motor, thus preventing it from overheating. Experimental tests and computational fluid dynamics (CFD) simulations have been carried out to investigate the effects of fan hub configurations on cooling airflow through the electric motor in automotive cooling fan systems. It has been found that radial ribs on the fan hub have significant effects on drawing cooling air through the motor. The comparison of the simulation results with the pressures measured in laboratory experiments show good agreement.

A numerical study was conducted to examine how leakages across apex seals affect the flow field in one combustion chamber of a motored, two-dimensional, Wankel rotary engine. Results are presented which show the effects of engine speed, leakage area, and compression ratio on velocity field, distribution of turbulent kinetic energy, and volume-averaged pressure when there are apex seal leakages. These results indicate that apex seal leakages can have a significant effect on the flow field. This numerical study is based on the density-weighted-ensemble-averaged continuity, “full compressible” Navier-Stokes, and total energy equations, closed by a k-ε model of turbulence with wall functions. The numerical method used to obtain solutions was the approximate factorization algorithm of the ADI type. All convection terms were treated by second-order accurate upwind differencing through flux-vector splitting. All diffusion terms were treated by second-order accurate central differencing.

A computer program -- LeRC3D.Wankel -- was developed to study the flow, spray, and spray combustion in the combustion chambers of Wankel rotary engines. LeRC3D. Wankel is based on an Eulerian-Lagrangian formulation. The gas phase was modelled by an Eulerian approach using the density-weighted, ensemble-averaged conservation equations of mass, momentum (full compressible Navier-Stokes), total energy, and species, closed by a low Reynolds number k-ε turbulence model. The liquid phase, made up of fuel droplets, was modelled by using a Lagrangian approach in which droplet groups are tracked in time. The combustion process which takes place after fuel droplets evaporate and mix with the surrounding air was assumed to be chemical kinetics controlled via a two-step global mechanism. This paper describes the formulation employed in the computer program as well as the essence of the numerical method used to generate solutions. Some computed solutions for the flow field are also presented.

The meaningfulness of numerical studies on Wankel engine flow fields depends strongly on turbulence modelling and the numerical methods used to obtain solutions. This investigation examined two different turbulence models and several variations of a numerical method for calculating turbulent flow fields inside one of the combustion chambers of a motored, two-dimensional Wankel engine. The two turbulence models examined were the standard k-ε model with wall functions and the low Reynolds number k-ε model of Chen and Patel. The numerical method used in this investigation was the approximate-factorization method of the ADI type with upwind differencing of the convection terms based on flux-vector splitting.