Physical Model

For the purposes of this study, it is sufficient to consider a small representative portion of the component, which was thus approximated by a slab of constant thickness. The slab was composed of a 2.5 mm (0.1 inch) ceramic layer and an iron substrate of the same thickness. As a part of the parametric study, two other ceramic thicknesses were also considered, 1.25 and 5.0 mm, respectively. The grid points in the ceramic and the substrate were generated in such a manner that the grid spacing was compact near the gas-ceramic and ceramic-substrate interfaces (Figure 15).' The smallest elements were located at the ceramic-substrate interface (from both sides) and at the gas-ceramic interface, and they were 0.015 mm (0.59/1000 inch) thick for the baseline case. There were twenty-one grid points in the insulating ceramic layer.

The gas-side boundary conditions were established by computer simulation of in-cylinder processes taking place in a heavy duty truck diesel engine operating at rated conditions, 2600 rpm and 200 psi BMEP.

Radiation and

r Element 1

Ceramic

2.5 mi

0 0

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