The performance and flow characteristics of a gas turbine combustor dump diffuser

Low speed tests have been carried out on a branched diffuser, geometrically similar to that employed in some gas turbine combustion systems. The fully annular test rig consisted of a straight walled, axisymmetric pre-diffuser, exhausting into a sudden expansion, the flow then being divided into two separate streams by a bluff body simulating the combustion chamber situated on the same centre-line as the pre-diffuser. The overall area ratio was maintained at 2.0, and tests vJere conducted with fully developed entry flo\~ for a range of pre-diffusers of 120 included angle, the design value of the ratio of mass flows in the inner and outer annuli surrounding the flame tube being fixed at 1.2. Further tests were conducted using a single pre-diffuser, a distorted entry velocity profile, and a design flow division around the flame tube of 2.15....