within a short diffuser with minimal diffuser jet momentum the primary nozzles 14 inject about 40 to 90 of the total energized fluid into ejector 10 it has been found that these nozzles must provide efficient passage of the energized fluid from the plenum 20 to the desired location and orientation of the discharge from the nozzle 14 as well as efficient passage of the induced or secondary flow around the exterior configuration of the primary injection nozzles 14 accordingly an important factor relative to the configuration of the primary injection nozzle 14 is the design of the internal duct and the external fairing for these elements to minimize the internal flow losses of the internal ducts 14a for the primary nozzles 14 a duct 14a which is continuously converging in the flow direction is desirable i e the area decreases from the point of communication with the plenum chamber 20 to the discharge point and which duct has a circular configuration at its discharge point the external surfaces of the primary nozzles 14 should be streamlined in the flow direction for this purpose air foil shapes as illustrated in fig4 can be utilized as long as they provide the desired streamline the selection of the.