A 2-Port, Space-Saving, Maintenance-Friendly Pneumatic Probe for Velocity Measurements

This paper presents the concept, design and experimental results of tests, in laboratory conditions, of a 2-port, space-saving pneumatic probe. The main features of the probe are a result of restrictions imposed by the functioning environment: a limited space for probe installation, the possibility of processing only two output signals and requirements for simplicity and reliability of the probe. A cylindrical shape of the probe tip is proposed as a general concept, similar to the classic, cylindrical, 3-port probe. The main difference arises in using only two pressure signals: one from the overpressure zone on the front side of the cylinder and another, from the underpressure zone on the back side. After performing an appropriate calibration procedure, it is possible to measure the flow velocity and correct the pressure difference obtained by means of a velocity coefficient k_v. This paper also presents an analysis of the k_v coefficient uncertainty to evaluate the quality of measurements.