A mixer/ejector suppressor is disclosed for reducing the noise level created by the exhaust flows in gas turbines. In the preferred embodiment, the suppressor comprises a mixing ring of alternating lobes attached to the engine's tailpipe; an ejector shroud mounted onto the mixing ring; and a plurality of arcuate gaps, between the mixing ring and ejector shroud, that permit ambient air to be entrained into the shroud. The preferred mixing ring has ten curved lobes of alternating designs. Five of the mixing lobes are shallow, with contours similar to those of mixing lobes in an earlier TSMEC version, disclosed in a related U.S. utility patent application, Serial No. 08/729,571. The other five lobes are much longer, and they are designed to penetrate deeply into the engine's hot core flow. Together, the ten lobes rapidly mix (mostly at supersonic conditions) the engine exhaust flows with secondary ambient air inside the shroud. The lobes thereby increase the spread rate of the exhaust jet, dissipate its velocity and greatly decrease the core length of the exhaust jet. Hence, noise levels are reduced, which enable older engines to meet new federal noise regulations, known as "Stage 3", at static and takeoff conditions.
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