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Flow Measurement
Published in Syed R. Qasim, Wastewater Treatment Plants, 2017
The Parshall flume is based on fundamental open channel flow principles. It consists of three parts: a converging section, a throat, and a diverging section. The Parshall flume creates a change in flow pattern by a decrease in width and a simultaneous drop in water surface elevation at the throat. Because the throat width is constant, the free discharge is obtained from a single upstream measurement of depth. However, if the flume is operating under submerged conditions, the downstream depth must also be measured. Calibration curves are prepared for converting the depth readings to discharge. Parshall flumes are self-cleaning and offer small head loss, and calibration can be checked with manual measurement of head. Disadvantages include high cost and less accuracy compared with pressure meters, and a relatively long and straight approach channel is required. The design procedure for a Parshall flume is given in Chapter 14. A typical installation of Parshall flume with float actuated liquid level recorder is shown in Figure 10-2(b).
Force-System Resultants and Equilibrium
Published in Richard C. Dorf, The Engineering Handbook, 2018
The Parshall flume is widely used for wastewater and irrigation water flow measurement due to low head loss; this device has self-cleansing capacity and the ability to operate accurately over a significant flow range; it consists of an inlet, a downward-inclining throat, and a diverging outlet. Depth measurement is taken from a stilling well at the inlet. The following formula applies to throat widths of 1 to 8ft and a medium range of flows: Q=4W×Ha1.52×W0.026
Instrumentation and Test Methods
Published in Paul N. Cheremisinoff, Handbook of Water and Wastewater Treatment Technology, 2019
The Parshall flume is a device for measuring liquid flow in open channels. The Parshall flume is a constriction of the channel that develops a hydraulic head which is proportional to flow. Figure 18 shows the shape and sections of a Parshall flume. Parshall flume sizes refer to the width of the throat section. Flumes are available in sizes from 0.025 up to 15 m. Large flumes are constructed on site, but smaller flumes can be purchased as prefabricated structures or as lightweight shells which are set in concrete.
Machine learning model development for predicting aeration efficiency through Parshall flume
Published in Engineering Applications of Computational Fluid Mechanics, 2021
Seyed Babak Haji Seyed Asadollah, Ahmad Sharafati, Parveen Sihag, Nadhir Al-Ansari, Kwok-Wing Chau
Parshall flume is one of the most commonly used fixed hydraulic structures to measure the surface water and irrigation flows. For a long time, numerous investigators focused on one or more flume components to simplify, improve, and refine its design and operation. Result of those intense experimental researches, the Parshall flume was eventually developed. A brief review of Parshall flume development is offered to benefit those unfamiliar with its history. Cone (1917) initiated a flume made up of a converging section, a diverging section, and a short throat section in-between them. His ‘venturi flume’ had the ground part as flat throughout the length. Parshall and Rohwer (1921) and Parshall (1928) had designed the present flume and expanded its applications in agriculture. His designed Parshall flume has an upstream converging section, end with downstream diverging exit section & in-between flat throat that has defined width with a downward sloped floor & upward slope section. Various shape weirs & Venturi flumes were used to measure flow at that time, but these devices had various limitations and disadvantages. Six years after his work began on the development of ‘modified venturi flume’, Dr. Parshall filed for the patent of his construction of a new ‘Parshall flume’. Then these flumes were installed in various American irrigation facilities (Heiner & Barfuss, 2011).