A Modeling Methodology for the Analysis of Abradable Powder Piston Skirt Coatings

Line2Line’s patented abradable powder surface coatings are a mechanism by which clearance between mating components is reduced, and the tribological properties of the interacting surfaces can be improved. The following discussion presents the modeling efforts targeting the numerical analysis of abradable powder piston skirt coatings. This study employs the Cylinder-Kit Analysis System for Engines (CASE) by Mid-Michigan Research to model the performance enhancements offered by abradable powder coatings as applied to piston skirts. Two piston models were generated for the purposes of this analysis, one with the post-run stock reference geometry and coating, as supplied by the manufacturer, and the second having the Line2Line post-run coated geometry. The pistons modeled had been installed within two separate Cummins R2.8 L turbo diesel engines, both of which were subject to several hours of runtime. The primary finding of the current study is that the Line2Line abradable powder coated pistons, henceforth referred to as “APC” pistons, exhibited significantly less post-run clearance than the stock coated piston. The concept of “integrated skirt clearance” (ISC) is introduced. Integrated skirt clearance is a quantity that represents the volume between the piston skirt and cylinder liner. CASE is then employed to model the piston dynamics, frictional losses, and ring groove side wear associated with both the stock coated piston and the APC piston. The APC pistons are predicted to experience much less secondary motion than the stock coated piston. Less secondary motion results in lower ring groove side wear. Finally, a methodology is presented for the optimization of the piston skirt profile. The optimization employs both CASE and HEEDS by Siemen