Advanced Combat Vehicle Piston (ACVP)

Commercial internal combustion engine designs for high-performance direct-injection heavy-duty diesel pistons focus on increasing brake thermal efficiency (BTE) as a means to increase fuel economy and reduce vehicle emissions on the large continental US fleet of class 7/8 semi-tractor trailers operating today.  For military applications, specifically combat vehicles, emissions are less of a concern; power density (>90 bhp/L) and low heat rejection operation (<0.5 kW/kW) are a primary focus.  Increases in power density and decreases in heat rejection directly correlate with smaller powertrain and cooling system packages.  A decrease in size, weight, and performance (SWaP) on these articles provides increasing returns in smaller vehicle sizes and decreasing combat vulnerability.   However, increasing power density and decreasing cooling system size requires operating conventional piston designs on the edge of material failure for traditional 4140 forging designs.  Innovative concepts and instrumentation techniques to validate these design concepts are needed to develop new piston materials to enable higher temperature operation (goal of 600oC) while sophisticated designs are required to manage thermal losses to enable high piston temperature. Exo-Atmospheric Technologies, LLC (Exo-AT), together with subcontractor Oak Ridge National Laboratory (ORNL), will demonstrate a novel H13 tool steel piston produced using additive manufacturing to enable sustained operation at 600oC while withstanding localized heat fluxes exceeding 20 MW/m2 during high-load operation on the piston surface.  The piston will be fabricated at the ORNL Manufacturing Demonstration Facility (MDF) and bench-top tested at the Exo-AT facility to verify low heat rejection characteristics and to develop advanced instrumentation for Phase II engine testing.