Fire testing laboratory
The objective is to control airspeed in an air tunnel at different values to allow fire tests, in turn, to be carried out simulating the conditions experienced by an aircraft fuselage in flight. The air is injected into the tunnel by a compressor and the air speed is adjusted via a butterfly valve located at the transition to the tunnel.
The figure alongside shows a diagram of the installation where, prior to applying ADEX, it was not possible to apply automatic control satisfactorily due to the following reasons a) The compressor uses an autoregulation system to control the output pressure which is affected by any valve movement b) The measurement of air speed is affected by a great deal of noise, c) The relationship between the control signal and the valve, and the air speed obtained resulted in hysteresis and a very high gain.
In the majority of tests, the desired value for the airspeed is 100 knots although in some cases, a speed of 70 knots is required. The figure shown alongside presents the airspeed transition from 70 to 100 knots. A pure time delay of 5 seconds can also be seen along with a high level of noise in the measured speed, and the small variation (only a few millivolts) in the positioning of the valve with which ADEX achieves the desired transition.
