Patent ID: 8146342

Claim:
An auxiliary power unit of an aircraft, comprising: an exhaust eductor system in a compartment of the auxiliary power unit, a primary exhaust nozzle configured to transport an active flow stream, the primary exhaust nozzle terminating with a nozzle end; a mixing duct at least partially surrounding the primary exhaust nozzle and configured to transport a passive flow stream that is entrained by mixing with the active flow stream from the primary exhaust nozzle, the mixing duct having an interior; and a baffle on the interior of the mixing duct, the baffle having an upstream end that is downstream of the nozzle end, and configured to prevent the mixed flow streams from exiting the mixing duct back into the auxiliary power unit compartment, wherein the upstream end is attached to the mixing duct and terminates at a downstream end, wherein the baffle has a cross-section through a radial-axial plane with a curvature extending from the upstream end to the downstream end that is generally circular or generally elliptical.