Experimentally determined effects of educator geometry on the performance of exhaust gas eductors for gas turbine powered ships.

Abstract

Cold flow model tests of exhaust gas eductors with constant area mixing stacks were conducted to evaluate the effects of geometric configuration on eductor performance. Single-nozzle and four -nozzle designs were tested. The other geometric variables were mixing stack length to diameter ratio (L/D) , primary nozzle standoff to diameter ratio (S/D) , and mixing stack entrance configuration. Non-dimensional parameters governing the flow phenomena are developed from a one-dimensional analysis of a simple eductor system. The eductor performance is evaluated in terms of these nondimensional parameters. The four- nozzle configurations were found to have better performance than single-nozzle configurations for L/D's less than eight. The effects of L/D, S/D, and entrance shape on performance were found to be highly interdependent at short L/D's. Performance for L/D's greater than four was found to be independent of S/D within the range of S/D's studied.