Model tests of multiple nozzle exhaust gas educator systems for gas turbine powered ships.

Abstract

Cold flow model tests of multiple nozzle exhaust gas eductor systems with constant area mixing stacks were conducted to evaluate effects of geometric configuration on eductor performance. A one-dimensional analysis of a simple eductor system based on conservation of momentum for an incompressible gas was used in determining the non-dimensional parameters governing the flow phenomenon. Eductor performance is defined in terms of these parameters. An experimental correlation of these parameters is developed and used to determine the effects of variations in eductor geometry on eductor performance. Three basic eductor configurations were tested with mixing stack L/D between 2.3 and 2.8, mixing stack to nozzle area ratios ranging from 2.28 to 3.03, primary nozzle exit Mach numbers from 0.070 to 0.265 and primary nozzle combinations of three, four and five nozzles each. Within the range of variables considered, the mixing stack area to primary nozzle area ratio and the resistance to secondary air flow into the eductor had the most influence on eductor performance.