Abstract: A vortex flow apparatus including a cylindrical housing that contains a fluid that flows in a swirling circular path. The apparatus may be utilized as a muffler for a combustion engine, a particle separator, or an energy conversion device that physically or chemically acts upon the fluid flow and particles contained within the apparatus. The housing defines an inlet opening that opens into the first end of the housing proximate a first end wall. An outlet tube defines an outlet opening through a first end wall. A projection is attached to a second end wall of the housing and extends into the housing. The outlet tube and projection are aligned with and centered relative to a central axis.