Stagnation pressure transient control in a supersonic blowdown wind tunnel test facility

Abstract

Research in the area of wind tunnel flow parameters control has been intensified in recent years, in an attempt to improve quality and efficiency of the wind tunnel operation. In this paper, stagnation pressure transient control in a supersonic blowdown-type wind tunnel is considered, with the aim of increasing available measurement time and bringing improvement in the operation efficiency. The stagnation pressure control strategy in the VTI Belgrade T-38 wind tunnel is analyzed. A mathematical model of a blowdown wind tunnel is developed and applied to the T-38 test facility. The model is used to incorporate a modified stagnation pressure transient control in the original T-38 control system, in order to establish the required stagnation pressure with the shortest possible settling time. The actual wind tunnel tests confirm model-predicted decrease of the pressure settling time and increase of available measurement time, bringing significant improvement in the facility operation efficiency.