THE INFLUENCE OF THE REGULATOR DIAMETER AND INJECTION NOZZLE GEOMETRYON THE FLOW STRUCTURE IN PNEUMATIC DIMENSIONAL CONTROL-SYSTEMS

The present paper describes an experimental investigation of the vario us parameters affecting the operation of industrial pneumatic controll ers based on the jet nozzle principle. A test rig was built to monitor supply pressure, air temperature, airflow characteristics, and the st atic pressure distribution over the flat plate on which the jet imping es. The results demonstrate the existence of a low pressure, separated flow zone, subject to fouling, which subsequently was eliminated by a ppropriate changes of the injection nozzle geometry. The previous expe rimental findings were also confirmed by numerical simulation of the f low. Experimental results also show that the internal diameter of the regulator situated inside the measuring branch, has an important influ ence on the sensitivity of the apparatus, as well as influencing its r ange.