Notches and weirs nptel pdf

Sharp created weirs a rectangular, b cipoletti or trapezoidal and c vnotch or triangular. A suppressed weirs notch width b is equal to the channel width b. Orifices, vena contracta, hydraulic coefficients lesson 20. When a v notch weir is used to meter flow, the weir equation q 2.

Also, applicable graphs are for 8 curb heights which may not meet rio rancho standards. Darcyweisbach equation, hydraulic gradient and total energy lines. Nptel provides elearning through online web and video courses various streams. It will help them improve work efficiency and performance in interviews for better jobs. Flow through orifices, mouthpieces, notches and weirs lesson 19. Weirs and notches are honest friends traditionally, weirs and notches have been used to ensure various functions in water and wastewater treatment plants.

How are notches and weirs used to measure flow in a canal. Cipoletti trapezoidal weir figure 33 and the 90o vnotch weir. Schematic diagram of v notch weir the discharge q over a triangular weir in terms of height of water over the weir h. These are used for measuring the flow of water from a vessel or tank with no pressure flow. Basics of mechanical engineering with introduction to all courses, subjects, topics and basic concepts it is advisable for all mechanical engineers to keep on revising these concepts. A notch is an opening in the side of a tank or reservoir. Notch is made of a metallic plate and its use is to measure the discharge of liquids. Discharge characteristics of triangular notch thinplate weirs by john shen abstract the triangular notch, thinplate weir is a convenient, inexpensive, and relatively precise flowmeasuring instrument. Water resources engineering ii notes pdf wre ii notes pdf. The intake structure is built at the entry to the irrigation system see fig. All other weirs are classified as weirs not sharp crested. Flow over notches and weirs pdf flow over notches and weirs a notch is an opening in the side of a tank or reservoir which extends above. Flow over weirs by john fuller fluid mechanics lab. Notches and weirs definition, types, differences, applications.

Before moving further in our discussion on notches and weirs let us first understand two important terms, which will help us in understanding types of both. For small scale applications, weirs are often referred to as notches and are sharp edged and manufactured from thin plate material. Then, the experiment is to study the discharge coefficient of fluid flow by these notches. Civil engineering topic wise complete solution with full explanation hi, welcome to our youtube channel kivip tech. A notch is used to measure discharge of a small stream or canal. It is used to measure rates of flow that may become very small.

You can find most of the materialsnotes related to civil engineering. Use a v notch weir to measure open channel flow rate bright. Gate masters academy g a t e m a s t e r s fluid mechanics 2 flow over notches and weirs dq dl q l 300 dl 900 l dl 33. The relationships of flow over weirs can be obtained. The basic principle is that discharge is directly related to the water depth above the crotch bottom of the notch. About this video in this video series i am starting to. Among these diverging structures weir is the most commonly used structure, because of its simple design and operation. Flow over notches and weirs fluid mechanics discharge. Rectangular weir v notch weir parshall flume broadcrested weir criterion for establishing control section for discharge measurement structure establishing the control section should.

A partially contracted weir has bb between 0 and 4h max. The only difference between a notch and a weir is that t. The flow area decreases as h increases, so a reasonable head is developed even at a very small flow rate. Design of weirs and barrages soil mechanics chemical. The discharge over a notch apparatus shows clearly the use of weirs as simple flow regulators. Pdf fluid mechanics pdf by rk bansal download mechanical geek. A weir has considerable width along the length of fluid flow. Note due to issue this book is not fully available only half part. Its purpose is to direct water from the original source of supply lake, river, reservoir etc. Discharge characteristics of triangularnotch thinplate weirs. What is the purpose of ventilation holes in case of a suppressed rectangular weir. It works with and fits on the top of tecquipments digital hydraulic bench h1f, available separately it allows students to do tests on relationships between upstream water level and weir discharge for various different shaped notches. In hindi what is notches and weirs and its types in hindiab classes,fluid mechanics duration. Concept of major and minor losses in pipe flow, shear stress, friction factor, and friction head loss in pipe flow.

Under the assumed flow conditions, how ever, the weir is a control structure, and the froude. Sep 30, 2016 10 awesome gadgets every student should have. Weirs fluid mechanics engineering numerical components. Weirs a weir is a barrier in an open channel, over which water flows. However, they both differ in their location and applications. Weirs are constructed as an obstruction to flow of water.

Weirs are classified based on the shape of their opening or notch. According the effect of sides on nappe or vein, weirs can be classified as. Spend time on studying, not for searching material to study. For v notch, the average discharge coefficients is 2. A structure, used to dam up a stream or river, over which the water flows, is called a weir. They are of particular use in large scale situations such as irrigation schemes, canals and rivers. These notes are according to the r09 syllabus book of jntu. A weir is a concrete or masonry structure which is constructed across the open channel such as a river to change its water flow characteristics. The purpose of the slope, on the sides, is to obtain an increased discharge through the triangular portions of the weir, which, otherwise would have been decreased due to end contractions in the case of rectangular weirs. A v notch weir sometimes called a triangular weir is shown in figure 2 a and in figure 3, below. The bottom edge, over which the liquid flows, is known as sill or crest of the notch and the sheet of liquid. All rectangular notch models were fabricated from acrylic glass sheets of 4 mm thickness. Different types of weir can be used as diverging structures some of them are given below. Discharge weirs fluid mechanics engineering reference.

Rectangular notch consider the flow in an element of height at a depth below the surface. Figure 3 shows the form for each model, where b is the weir notch width, h is a notch height, h is a depth of water over the crest, and p is the crest height. Notches and weirs pdf weirs are identified by the shape of their opening, or notch. The cippoletti weir is a trapezoidal weir, having 1 horizontal to 4 vertical side slopes, as shown in figure. Notches and weirs both are the openings to the fluid flow to regulate it. Flow measurement study notes for mechanical engineering. In any hydropower projects the diversion structures occupies the key position.

A weir is generally used to regulate flow of water at a large scale, like in rivers or canals. A rectangular notch in a thin square edged weir plate installed in a weir channel as shown in figure 4. A notch is regarded as an orifice with water level below its upper edge. Discharge losses, time for emptying a tank lesson 21.

Flow through orifices, mouthpieces, notches and weirs. Notch a notch may be defined as an opening provided in one side of a tank or a reservoir, with upstream liquid level below the top edge of the opening. Paper open access discharge coefficient for rectangular. The weir notches that are mounted in a carrier at the outlet end of the flow channel 9. Now to have better clarity on notches and weirs, we should understand differences between them. The aim of this paper was the deduction of a new stagedischarge relationship for a contracted weir, having a crest length less than the channel width, by using the malchereks outflow theory. Notches are openings which is used to measure discharge through it. Niranjan sahoo iitguwahati dymamics of fluid flow flow over notches and. These devices, placed in open channels to obstruct water flow, are simple to construct and install. Sharp crested weirs for open channel flow measurement. Pitot tube, venturi meter and orifice meter classification of orifices, flow over rectangular, triangular and trapezoidal and stepped notches broad crested weirs.

The flow rate over a weir is a function of the head on the weir. The simplest is the rectangular notch or in certain cases the square notch. Weir types in treatment plants a weir measures the flow rate by mea. However, if the hydraulic gradient becomes big, greater than the critical value, then at the point of existence of water at the downstream end, it begins to dislodge the soil particles and carry them away. Discharge coefficient for rectangular notch using dimensional analysis technique.

Use a v notch weir to measure open channel flow rate. It doesnt matter how thick the weir is except where water flows over the weir through the v. Dimension reasoning, dimensional homogeneity, dimensional analysis using rayleighs method, buckingham. The common types of weir are the sharp crested weir such as rectangular weir, v notch weir, or cipolletti weir and the broad. However a weir is a notch but in a very large scale a notch is used to measure relatively smaller discharge examples include discharge in a flume, water lining etc while a weir is used to measure larger discharge examples are discharge in a stream or river, strome discharge etc.

V notch weirs the v notch, sharpcrested weir is especially good for measuring low flow rates. The rectangular weir notch is a common device used to regulate and measure discharge. Types of notches, rectangular and triangular notches, rectangular weirs lesson 23. Jun 22, 2019 iari toppers provides agriculture notes,icar e course notes,jrf notes,ibps afo,e krishi shiksha,tnau notes,angrau notes,agriculture jobs update,jrf mock test,jrf old exam paper for agronomy horticulture,plant science,agriculture statistics,soil science,social science,icar ecourse pdf download,best agriculture books etc. Measuring open channel flow rates with a weir or a flume. Outline notch types of notch weir types of weir difference. Nptel course developer for fluid mechanics module 04.

That is why, a notch is, sometimes, called as a weir and vice versa. Below are the differences between notches and weirs in tabular form. Gandhi harshil rajubhai 141100106018 deshmukh bhavik hasmukhlal 15dtod002 kotila jayveer vanrajbhai 15dtod007 mistry aditya pramodbhai 15dtod008 pandya dhrumil dipakbhai 15dtod009 subject. A weir with a sharp upstream corner or edge such that the water springs clear of the crest is a sharp crested weir. The conditions of flow, in the case of a weir, are practically the same as those of a rectangular notch. Thinplate v notch weirs are neal scryer and friends pdf commonly used as measuring devices.

Broad crested weir broad crested weirs are robust structures that are generally constructed from reinforced concrete and which usually span the full width of the channel. Package weirs august 20, 2015 title a hydraulics package to compute openchannel flow over weirs version 0. Open channel flow rate can be measured with a weir, which is a vertical obstruction in the flow path, or a flume, which is a constriction in the width of the channel. The coefficient of discharge for both notches is different due to the height of the depth water level. Three black marbles are dropped at the same time into three different fluids oil, water. Apr, 2014 weirs not sharp crested are classified according to the shape of their cross section, such as broadcrested weirs, triangular weirs, and trapezoidal weirs. The depth of water above the base of a weir is related to the flow rate through it. Calibration of rectangular notch fluid mechanics experiments. A sharpcrested weir allows the water to fall cleanly away from the weir, e.

Conclusion the flow over weirs experiment is to determine the characteristics of openchannel flow over, a rectangular notch and v notch. Usbr 1997 suggests using the v notch weir equations for the following conditions. It is used as both a discharge measuring device and a device to raise water levels. Regardless of the reason, there is a need to be able to calculate discharge equations for intermediate v notches. These are commonly used to measure the volumetric rate of water flow, prevent flooding and make rivers navigable. Fluid mechanics pdf notes fm pdf notes smartzworld. The triangular notch has advantages over the rectangular notch since the shape of the nappe does. Classification of notches and weirs fluid mechanics youtube. Calculate the discharge coefficient for sharpcrested weir experimentally on a hydraulic. Sharpcrested weirs are classified according to the shape of the weir opening, such as rectangular weirs, triangular or v notch weirs, trapezoidal weirs, and parabolic weirs. A weir is a notch on a large scale used for measuring the flow of a river, canal etc.

Assuming that the flow is everywhere normal to the plane of the weir and that the free surface remains horizontal up to the. Weirs may have a variety of forms and are classified according to the shape of the notch or opening. Orifice notch weir difference between notch and weir. Fluid mechanics notes pdf, fluid mechanics book, fluid mechanics pdf notes 1. Niranjan sahoo iitguwahati dymamics of fluid flow flow over notches. Pdf discharge characteristics of weirs of finite crest. In r and r15,8units of r09 syllabus are combined into 5. Weirs fluid mechanics engineering numerical components in. Sharp crested weir broad crested weir ogee weir tyrolean weir weir with lateral intake etc. Examples of three wellknown weir types are illustrated. A value of q 0 or k f 1 indicates no notch sensitivity, whereas a value of q 1 or k f k t indicates full notch sensitivity. A rectangular weir whose notch opening sides are coincident with t sides of the. Head h should be measured at a distance of at least 4h upstream of the weir. A weir having thin edged crest such that the over flowing sheet of water has the minimum surface contact with the crest.

Flow over notches and weirs pdf may 4, 2019 admin flow over notches and weirs a notch is an opening in the side of a tank or reservoir which extends above the surface of the liquid. Che241 lab report solteq flow over weirs fm26 2015. In open channel flows, weirs are commonly used to either regulate or to measure the volumetric flow rate. Thinedged weir and sharpcrested weir are used to designate a weir in which the nappe, or overfalling sheet, touches only the smooth, sharp upstream corner or edge of the crest, the thickness of. Oct 07, 2018 in hindi what is notches and weirs and its types in hindiab classes,fluid mechanics duration.

What is the difference between steady and unsteady flow. Thinedged weir and sharpcrested weir are used to designate a weir in which the nappe, or overfalling sheet, touches only the smooth, sharp upstream corner or edge of the crest, the thickness of which is probably immaterial so long as this condition is fulfilled. Weirs are to be evaluated using the following equation. While other times the flows of a particular site dont match up well with the flow characteristics of the standard sizes of v notch weirs. In some cases, the irrigation water source lies below the level of the irrigated fields. The bottom edge of notch over which water flows is known as sill or crest. A weir is a notch on a larger scale usually found in rivers.

The v or triangular notch is a vshaped notch with the apex downward. Fluid mechanics by modi and seth, standard book house. In open channel hydraulics, weirs are commonly used to either regulate or to measure the volumetric flow rate, they are of particular use in large scale situations such as irrigation schemes. Sometime there is a need to correct for a weir plate cut at an incorrect angle. The bottom edge, over which the liquid flows, is known as sill or crest of the notch and the sheet of liquid flowing over a notch or a weir is known as nappe or vein. The only difference between a notch and a weir is that the notch of a small. In conclusion v notch has a higher discharge coefficient. Weirs are structures consisting of an obstruction such as a dam or bulkhead placed across the open channel with a specially shaped opening or notch. Compute different hydrauli ccoe f ient for di er n types of orifice 4b. Barrages causes of failure of weir or barrage on permeable foundation failure by subsurface flow failure by piping or undermining failure by direct uplift failure by surface flow by hydraulic jump by scouring blighs creep theory for seepage flow total length of pucca floor including twice the length othe cutoff, l ch l h thickness of the floor, t 1. Either one causes a change in water depth in the channel, which can be correlated with flow rate. Pdf discharge coefficient for rectangular notch using. It is especially good for measuring a low flow rate, because the area of flow through the v notch becomes quite small while the head over the v notch is still a measurable value. Flow over notches and weirs free download as pdf file.

The bottom edge of north over which the liquid is flow is. Four rectangular weirs notches, known as rw, were used in this study on different models. Basics of mechanical engineering mechanical engineering. A notch is, usually made of a metallic plate and is used to measure the discharge of liquids.

Aug 08, 2015 download fluid mechanics by rk bansal pdf book. The v notch weir is widely used to measure open channel flow rate. The goal of this site is presently to help the undergraduates pursuing b. Discharge over a notch fluid mechanics tecquipment. Water resources engineering ii notes pdf wre ii pdf notes wre ii notes pdf file to download are listed below please check it link. Since the top edge of the notch above the liquid level serves no purpose, therefore a notch may have only the bottom edge and sides.

Rectangular weir discharge calculator and equations. For a weir to be fully contracted, bb must be greater than 4h max, where h max is the maximum expected head on the weir usbr, 1997. The objective of this lab is to determine the characteristics of openchannel flow over, firstly, a rectangular notch and then a triangular vee notch, also to determine the. Thinplate vnotch weirs are neal scryer and friends pdf commonly used as measuring devices. Venturi meter, orifice plate, pitot tube, notches and weirs. Design of weir weir design manual calculations and. Coefficient of discharge triangular notch experiment. Notch sensitivity and fatigue notch factor, k f values of k f for r 1 generally range between 1 and k t, depending on the notch sensitivity of the material, q, which is defined by. Sharpcrested weir trapezoidal these weirs are trapezoidal shaped with notch side slopes of 4.