diffuser

A specially designed duct, chamber, or section, sometimes equipped with guide vanes, that decreases the velocity of a fluid, such as air, and increases its pressure, such as in a jet engine, a wind tunnel, etc. In a gas turbine engine, the diffuser converts the velocity energy of the air leaving the compressor into pressure energy before it passes into the combustion chamber. The diffuser may be formed as an integral part of the compressor casing or be bolted to it. It consists of a number of tangential vanes, whose inner edges are parallel to the direction of the resultant airflow from the rotating compressor. The passages between the vanes are proportioned so that air pressure attains the requisite entry value on entry to the combustion chambers.

Location of diffuser in axial and centrifugal flow engines.