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

100%

Olczyk A. , Magiera R. , Kabalyk K.

Metrology and Measurement Systems

2018

tom Vol. 25, nr 1

171--185

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 kv. This paper also presents an analysis of the kv coefficient uncertainty to evaluate the quality of measurements.

Preliminary evidence on laboratory experiments to detect the impact of transient flow on bedload transport

51%

Przyborowski Ł. , Nones M. , Mrokowska M. , Książek L. , Phan C. N. , Strużyński A. , Wyrębek M. , Mitka B. , Wojak S.

Acta Geophysica

2022

tom Vol. 70, no 5

2311--2324

Trapezoidal-shaped hydrographs are typical of anthropized rivers, as this form is generally associated with the release of water from hydropower dams. To investigate how such unnatural waves can affect bedload rate, preliminary fume experiments were performed in Krakow, Poland, looking at bedload transport rate, bed shear stress and bed morphology. In addition, close-range bed surface photogrammetry was used to investigate bed changes due to the passage of the food wave. Three scenarios, having the same water volume but different wave magnitudes, were tested. The lowest wave showed almost no sediment transport and no visible changes in bed morphology, while higher waves changed the bed morphology, creating erosion and accumulation zones. The highest wave was characterized by an 8-shaped hysteresis of the bedload rate with a peak during the wave maximum. The lag time between the maximum bedload rate and the wave plateau was longer than expected due to zero-slope conditions.