The two-dimensional convergent-divergent nozzle with a circle-to-square convergent part was designed. The project of the throat area control with pneumatic injection was numerical simulated. The influences of nozzle exit width-to-height ratio

pressure drop ratio and injection angle on the throat area and nozzle performance were analyzed. The results show that the static pressure near the wide side in the rectangular nozzle throat section is lower than that near the narrow side. The static pressure near the wide side decreases and that near the narrow side increases with the increase of exit width-to-height ratio. At the same pressure drop ratio

the range of throat area control(RTAC) and the efficiency of throat area control(ETAC) increase while the nozzle coefficient of total pressure recovery decreases with the increase of exit width-to-height ratio. At a fixed exit width-to-height ratio

RTAC and ETAC decrease firstly and then keep at the same level while the nozzle coefficient of total pressure recovery increases with the increase of pressure drop ratio. ETAC increases with the increase of injection angle.