Pancake Engine Bore 105 [mm] Stroke 95.25 [mm] Connecting Rod Length 158 [mm] Compression Ratio 8.56 Table 2.
In fact in , the authors proved that heat transfer models widely available in CFD commercial codes behave correctly when applied to the well-known GM pancake engine test case, while they manifest evident shortages when used for highly-charged / highly-downsized spark ignition engines, operated at high revving speed.
This is possible only for simple domains such as the GM pancake engine analyzed in the next paragraph.
In the first one, the GM pancake engine test case is deeply investigated, as a representative of the part-load and low revving speed operating points, in order to evaluate the heat transfer prediction in case of [y.sup.+] values lower than the turbulence model requirement.
In this section the General Motors pancake engine is considered as a representative of part-load and low revving speed operating conditions.
In particular, it is fundamental to point out that the GM pancake engine combustion chamber geometry is simpler compared to the ones of current production engines.
As for the proposed formulation, its application to the pancake engine seems to relevantly underestimate the heat transfer from the gases to the walls.
As visible, for a given wall function the value of [zeta] in the pancake engine is always much higher than that for the production engines.
To conclude, it is possible to say that despite the relevant heat fluxes, much higher than those of the pancake engine, the investigated production engines exchange less energy through the combustion chamber walls and are therefore characterized by lower [zeta] values.
Pancake engine geometrical data Bore 105 [mm] Stroke 95.25 [mm] Connecting Rod Length 158 [mm] Compression Ratio 8.56 Table 4.