Testing of a shrouded, short mixing stack gas eductor model using high temperature primary flow.

Abstract

An existing apparatus for testing models of gas eductor systems using high temperature primary flow was redesigned and modified to provide improved control and performance over a wide range of gas temperatures and flow rates. Pumping coefficient, temperature, and pressure data were recorded for two gas eductor system models. The first, previously tested under hot flow conditions, consisted of a primary plate with four straight nozzles and a slotted, shrouded mixing stack with two ring diffuser (L/D=2.5). The second was geometrically similar to a model previously tested in cold flow. This model employed a primary plate with four tilted-angled nozzles and a slotted, shrouded mixing stack with two ring diffuser (L/D=1.5). Thermal imagery was used to generalize the data obtained by direct temperature measurement. The validity of cold flow model testing is confirmed. The short stack with tilted-angled primary nozzles is shown to have superior mixing and pumping performance, but to exhibit significantly higher shroud and diffuser surface temperatures.