Study on the Effect of Sonic Air Tab Location in Supersonic Jet Control

Abstract

This research presents the effectiveness of sonic air tabs positioned at varying distances from the nozzle exit in a Mach 2.1 supersonic jet, focusing on their impact on aerodynamic mixing efficiency. The study involved placing the air tabs at two locations: directly at the nozzle exit (0D) and 0.5D downstream from the nozzle exit. The Injection Pressure Ratio (IPR) was adjusted between 3 and 6 while maintaining a constant Nozzle Pressure Ratio (NPR) of 6. Core length measurements of the jet were conducted using pitot pressure measurements and shadowgraph techniques, comparing controlled and uncontrolled jet conditions. The findings revealed that under an NPR of 6 at 0D, the maximum reduction in core length reached 56.4% for IPR 6 and at 0.5D the maximum reduction was 31.4% for IPR 6. As the IPR increased from 3 to 6, the core length reduction rate increased proportionally at both air tab locations. However, the reduction rate was consistently higher when the air tabs were positioned at the nozzle exit compared to the 0.5D location. The results from shadowgraph images aligned with those derived from pitot pressure measurements. In conclusion, for an NPR of 6 positioning sonic air tabs directly at the nozzle exit (0D) proved more efficient than placing them at 0.5D.