REPUBLIC OF SERBIA

MINISTRY OF DEFENCE

www.mod.gov.rs

MINISTRY OF DEFENCE

Material Resources Sector

Defensive Technologies Department

Military Technical Institute

www.vti.mod.gov.rs

A NEW CONTROL SYSTEM FOR THE FLEXIBLE NOZZLE IN
THE t-38 TRISONIC WIND TUNNEL

BILJANA ILIĆ

Military Technical Institute, Belgrade, biljana.ilich@gmail.com

MIRKO MILOSAVLJEVIĆ

Military Technical Institute, Belgrade, mirko.milosavljevic.bgd@gmail.com

Abstract: Within the extensive project at the T-38 trisonic 1.5 m × 1.5 m wind tunnel of the Military Technical Institute, Belgrade, started with the objective to design and implement a new wind tunnel control system replacing the existing system dating from 1980s, the flexible nozzle position control was implemented. It was based on completely changed hardware and software platform, with more efficient position control algorithm, but using the same actuators and sensors as in the previous system. The improvement was achieved and confirmed by the wind tunnel tests, but previous problems with unreliable position sensors still remained. After these activities, the flexible nozzle control system was further improved introducing new position sensors, which brought major software changes and even more efficient position control algorithm. In this paper, design considerations for achieving the optimum position control and its implementation on a programmable automatic controller are outlined. A brief description of the system safety and diagnostic features is given. The flexible nozzle control system robustness was verified for complete Mach number envelope of the wind tunnel and results showed significant improvements in speed, accuracy, stability and reliability comparing to the previous one, enhancing the wind tunnel overall performance.

Keywords: Flexible nozzle, wind tunnel, programmable automation controller, position control.