Opposed Piston Opposed Cylinder (opoc™) 5/10 kW Heavy Fuel Engine for UAVs and APUs 2006-01-0278
The opposed piston opposed cylinder (opoc™) engine concept has been demonstrated as an engine concept with high specific power density and high power to volume ratio. The engine has several potential applications, including use as an auxiliary power unit (APU) in various commercial and military applications and as the primary power source for small unmanned air vehicles (UAVs). An engine in this power range operating on heavy fuels (e.g. JP5, JP8, DF2) is not typically available.
The engine uses a two-cycle supercharged uniflow scavenging system with asymmetric port timing and will run at speeds between 8,000 and 12,000 rpm. The unique design of the opoc™ engine produces a piston speed that is half the speed of a typical crankshaft engine running at the same speed. Uniflow scavenging produces gas exchange efficiencies rivaling those of four-cycle engines. The design also leads to reduced in-cylinder heat losses. Furthermore, the opoc™ engine is fully balanced. These significant benefits lead to an extremely lightweight and compact engine design.
Extensive 1-D gas exchange and 3-D scavenge process simulation and optimizations were used to design the combustion system. Traditional Computer Aided Engineering (CAE) practices in the area of Multi-Body Systems (MBS) simulation and thermo-mechanical Finite Element Analysis (FEA) were adapted to support the design and development of this engine.
This paper provides an overview of the design process with focus on the unique features of the opoc™ engine and presents the system engineering techniques used in its design along with some results.