Broad crested weirventuriflume almost same procedure the chairman lukongo ngenge. Simplified flow corrections for parshall flumes under. This present study focuses on determining the aeration efficiency of a small 3 inch parshall flume and modified venturi flumes from this parshall flume, in particular the effect of varying throat width, throat length and sill height. Venturi flume it is critical flow open flume with constricted flow.
Venturi flume vs venturi meter difference between venturi flume and venturi meter. The term venturi flume is used in flow measurement literature to describe a. A venturi flume is a criticalflow open flume with a constricted flow which causes a drop in the hydraulic grade line, creating a critical depth 1 2 it is used in flow measurement of very large flow rates, usually given in millions of cubic units. The inlet diameter equals d 26 mm and the throat diameter d 16 mm. Venturi flumes are used in openchannels to determine the discharge by the measurement of a water level. The experiments were conducted for 26 different modified venturi flumes and 1 parshall flume. Critical flow occurs in the flume throat followed by a hydraulic jump downstream. Such obstructions make the use of the ordinary rating flume very troublesome, if not quite.
Venturiflume it is a devise used to measure the discharge in an open channel. They consist of short length of pipe shaped like vena contracta, or the portion with the least cross sectional area, which fits into a normal pipeline. A pair of venturi sides to fit into the channel allowing demonstrations of flow measurement techniques used in rivers and waterways. Demonstration mode for d uflume or b all other flumes of 0. Venturi flumes are recommended for liquid flow measurement within open channels, particularly where suspended solids material is being transported, and are almost universally used in measuring the inflow to sewage trea. To find the coefficient of discharge for orifice meter. Flumes are devices having constricted cross section of free surface flow through channels. The original, or classical, venturi was invented by a u. Flow through venturi meter background and theory introduction flow meters are used in the industry to measure the volumetric flow rate of fluids. Flow rate is calculated from measured depth of flow if an equation relating this depth with flow rate is known. The experimental flume hm 160 has a closed water circuit. Both experiment and simulation were done for the channel. The headdischarge relationship of such measurement devices can be determined following the critical flow theory, but this approach is only valid if the length of the throat is sufficiently long.
This flume corresponds to a locally constricted channel normally without a. Article information, pdf download for flow regime changes at. Energy losses through venturi, orifice, and rotameter flowmeters. Hydraulics, venturi flume questions physics forums. Submerged flow condition due to adverse pipe slopes or flow during backwater conditions are accurately measured. A venturi meter would normally measure in millimetres, whereas a venturi flume measures in metres. Subcritical flumes like the parshall flume operate by accelerating slow, subcritical flow fr 1 by restricting the flow as it passes through the flume. It was thought that the flume might be converted into a selfcontained measuring device by placing a restricted section in the flume, which would cause a.
Differential pressure type flow meters head flow metersmeasure flow rate by introducing a constriction in. Flume width and water depth effects in sedimenttransport. The major objective of this experiment was to construct, test and model a simple, inexpensive venturi meter. The sediment leaving the flume was collected and measured over time intervals of 20 or 30 min, enabling the cumulative volume of lateral diffusion and deposition of bed load into the strips to be determined dotted lines, fig. It is critical flow open flume with constricted flow. Video of an experimental river flume in the basement of padnos hall of science. Williams abstract a newly constructed 52foot laboratory flume was used to study sediment transport in a series of 37 runs with a coarse 1. Flow regime changes at hydraulic jumps in an open venturi channel. The excel formulas in downloadable spreadsheet templates make open channel flow measurement calculations using parshall flume equations for either free flow or submerged flow. The experiments indicate that the venturi flume will be free from interference due to changes in the. The crosssection of the experimental section is 86x300mm. Stop logs are simple rectangular shapes which slot one after the other into the discharge end of the channel. The flow is determined using a sudden enlargement, venturi meter, orifice plate, elbow and a rotameter.
Flume experiments on the transport of a coarse sand by garnett p. The water flow rate can be adjusted using the valves on the hydraulics bench. Williams abstract this paper reports 177 flume experiments made in channels of different widths and water depths, the purpose being to find how the flume. Fm 308 flow measurement by venturi and orifice meter. Pdf modelbased drilling fluid flow rate estimation using venturi. A qh related ultrasonic volume measurement type nivumaster has been installed. When flow out of the parshall flume is returning to a channel or pipe, the epa recommends that the channel be straight and unobstructed for 520 throat widths although flow spilling freely off the end of the flume can eliminate this requirement. Broad crested weirventuriflume almost same procedure. After inputting the parshall flume throat width and the measured head over the flume, the excel formulas calculate the free flow rate through the flume. Venturi flume are described by characteristics such as material, connections and throat width.
Derive equations for the flow rate through a venturi flume. Information covering the detailed maintenance should also be provided in the associated pdf manuals. Pdf monitoring the flow rate out of the well is critical for good. A guide to methods and standards for the measurement. Due to solid matter contained in sewage, the discharge in sewer technology is usually measured with a venturi flume.
The experimental section is 2,5m long and can be increased to 5m with the extension element hm 160. Model based flow measurement using venturi flumes for. Rectangular venturi flume the original idea was to invent a device which would replace the ordi nary rating flume, such as is used in irrigation canals. In order to maintain the measuring uncertainty as low as possible, an ultrasonic sensor with a very low dead zone type pm3, dead zone 0. Energy losses through venturi, orifice, and rotameter. Charateristics of flow through a venturi flume objective the purpose of this experiment is to determine the relationship between upstream head and flow rate for water flowing through a venture flume and determine the discharge coefficient and observe the flow patterns. It is also a control flume that comprises a short constricted section followed by one expanding to normal width. Freeflow occurs in a flume when there is insufficient backwater to reduce the discharge through the flume. A venturi meter would normally measure in millimetres, whereas a venturi flume measures in metres 3. The first one requires and the second approach does not require crossing of critical depth by the liquid free surface somewhere in a flume. Notable factors in comparing application of the venturi solution to a pipe meter with using the venturi solution on a longthroated flume are the magnitude of head differential observed as flow moves from the approach section, then is accelerated through the constricted throat sections. Venturi flume experiment fluid mechanics flow measurement. It is designed in such a way that the velocity at the throat is less than the critical velocity so that no standing wave will occur in the flume.
It mentions venturi flume advantages or benefits and venturi flume disadvantages or drawbacks. A venturi flume is a criticalflow flume, wherein the critical depth is created by a local. Civil engineering lab ii group 3 hydraulics 1 hd 1. The name venturi flume is not used in this chapter, since this term is reserved for flumes in which flow in the constriction is subcritical. Flow level profile in the venturi flume with subcritical upstream flow. It is used in flow measurement of very large flow rates, usually given in millions of cubic units. Both open channel and full pipe flow rates during surcharged manhole. The main objectives of this experiment is to obtain. Advantages of venturi flume,disadvantages of venturi flume. Experimental and cfd analysis of flow through venturimeter. This causes drop in hydraulic grade line which creates critical depth.
This page compares venturi flume vs venturi meter and mentions difference between venturi flume and venturi meter. Venturi flume is used for very large flow rate measurements, usually in units of. A particularly attractive version of such a device is a standingwaveflume, as this enables determination of liquid discharge by onepoint. To transition the flow out of a parshall flume, wing walls should be used. Venturi flume experiment free download as word doc. This is placed between the two sections of the venturi and adjusted to clamp them against the side walls of the channel. These characteristics of the parshall flume make it particularly suitable for flow measure. A simple, inexpensive venturi experiment applying the. A schematic of the venturi meter is shown on the diagram at the end of the procedure. Trapezoidal, rectangular, u round bottom, palmer bowlus, parshall. The pressure along the meter is obtained using the 11 pressure taps at the locations shown on the diagram. Figure shows the plan and elevation of a venturiflume. The side walls of the experimental section are made of tempered glass, which allows excellent observation of the experiments.
Proposed drilling uid circulating system with a venturi ume clusions are made in section8. A control flume that comprises a short constricted section followed by one expanding to normal width. This tutorial is a continuation of tutorial 1 and 2 and these should be studied first. This constriction results in an increase of flow depth above the flume. Venturi flume for measuring water in open channels, in order that those in. The parshall flume accomplishes this restriction by contracting the side walls and dropping the floor. A venturi flume is a criticalflow open flume with a constricted flow which causes a drop in the hydraulic grade line, creating a critical depth. Model based flow measurement using venturi flumes for return flow. The obstruction caused to the flow of liquid at the throat of the venturi produces a local pressure drop in the. This flume corresponds to a locally constricted channel normally without a bottom inset to force a transition between sub and supercritical flows. An experimental investigation of the aeration performance. To find the coefficient of discharge for venturi meter. This pressure drop is measured using a differential pressure sensor and when.
The pressure drop associated with each meter is measured directly from the manometers. In addition, the thinplate venturi flume is presented that is proposed for larger channels or rectangular sewers of width up to 3 m, with an access by a standard manhole. The venturi meter is an obstruction meter named in honor of giovanni venturi 17461822, an italian physicist who first tested conical expansions and contractions. The experiment was performed in a parshall flume model that consists of. Venturi meter and orifice meter are the commonly used flow meters for measuring massvolumetric flow rate or velocity of the flowing fluid. There are two conditions of flow that can occur in a parshall flume. Venturi flumes with rectangular and trapezoidal cross sections fig. Ppt venturiflume powerpoint presentation free to view. A flume is a humanmade channel for water in the form of an open declined gravity chute whose walls are raised above the surrounding terrain, in contrast to a trench or ditch. Flume, boundary layer, venturi flume, palmerbowlus flume. A type of open flume with a contracted throat that causes a drop in the hydraulic gradeline. Fm 308 flow measurement by venturi and orifice meter objectives.
Homework statement a venturi flume is formed in a horizontal rectangular channel 1. Venturi flume is a very popular flow measuring device. Two different approaches to flow rate measurements by flumes have been compared. Venturimeter are used to measure the velocity of flow of fluids in a pipe. More specifically, this simple venturi meter, constructed from materials available at a local hardwareauto parts store, was characterized by determining the venturi coefficient and. Flume width and water depth effects in sedimenttransport experiments by garnett p. Flumes are not to be confused with aqueducts, which are built to transport water, rather than transporting materials using flowing water as a flume does. Both of these terms are of equal magnitude but different sign and combining. Hd 1 r1 civil engineering lab iigroup 3 hydraulics 1. When a venture meter is placed in apipe carrying the fluid whose flow rate is to be measured, a pressure drop occurs between the entrance and throat of the venturimeter. Flume experiments on the transport of a coarse sand. The venturi flume is held in place by a simple stretcher screw.