An ejector has a primary inlet (40), a secondary inlet (42), and an outlet (44). A primary flowpath extends from the primary inlet to the outlet. A secondary flowpath extends from the secondary inlet to the outlet. A mixer convergent section (114; 300; 400) is downstream of the secondary inlet. A motive nozzle (100) surrounds the primary flowpath upstream of a junction with the secondary flowpath. The motive nozzle has a throat (106) and an exit (110). An actuator (204) is coupled to the motive nozzle to drive a relative streamwise shift of the exit and convergent section.