High Speed Positive Displacement Injector for Rate Shaping Direct Injection

When internal combustion engines are converted to heavy hydrocarbon fuels, such as JP-8, they become prone to knock, which reduces power and shortens engine life.One method for avoiding engine knock is establishing stratified fuel/air charges within the cylinder, where near stoichiometric mixtures are retained in proximity to the point of ignition and lean elsewhere.However, generating stratified charges on small, high-speed engines, like those used for small UAVs is limited by the speed of the direct injection system.Busek proposes to develop a high-speed, piezo-actuated fuel injector for the purposes of fuel rate shaping to avoid engine knock in high speed engines.Rapid and controllable injection will be achieved by direct application of high force onto a prescribed incompressible volume, allowing for precise sub-millisecond actuation resolution while providing injection pressure amplification within the injector, thus reducing required fuel supply pressures.Relevant engines will be assessed and numerically modeled to ascertain optimum injection profiles for developing stratified charges.A proof-of-concept positive displacement actuator will be designed, fabricated, and tested via high speed imaging to confirm proper injector function at relevant time scales.Results shall be used to guide subsequent development of a prototype suitable for engine testing in Phase II.