Fluid velocity measurement devices pdf

Fluidlevel measurements can be accurately measured through the wall of a nonmetallic tank by placing an airdielectric transmission line up against. There is now a wide variety of methods available to measure the flow of liquids, solids, gases and vapours. Some flow measurement instruments that we daily find oil dispenser, water meter. Pdf fluid flow measurement techniques researchgate. These terms represent, for the turbulent momentum transport, time mean values of the products of velocity fluctuations.

Industrial flow measurement industrial flow measurement basics and practice. The sensing element the cathode is the wire end facing the flow, and the device casing is the anode. Among the major types of measurement devices used in surface water open channels andor closed conduits are. Measuring instruments for fluid velocity, pressure and wave. Measurement of the temperature of a fluid using an alcohol thermometer.

An introduction to flow measurement with rotameters. The device used for measurement of viscosity is known as viscometer and it uses. The actual velocity of the fluid at a given point measured in metres per. A venturimeter is a device meant for measuring the quantity of a liquid flowing through a pipe. The barometer is a device meant for measuring the local atmospheric pressure. The velocity triangle can be applied to predict the combination of fluid conditions and turbine speed necessary to establish positive turbine power.

Some are made specifically for air velocity measurement and are calibrated directly in feet per minute. Flow measuring devices are generally classified into four groups. Quick and easy to use, it is a portable instrument calibrated to provide a direct reading of air velocity. This article is a summary of chapter 12 or annex a of the manual sediment transport measurements in rivers, estuaries and coastal seas. The viscosity is fluid property that depend on pressure and mostly on temperature. Fluid velocity calculator pipe line velocity calculator. Theory overview of flow measurement using differential pressure devices based on iso5167 standard. Iso 4006, measurement of flow of fluids in closed conduits vocabulary and symbols. Iso 5168, measurement of fluid flow estimation of uncertainty of a flowrate measurement.

Thus far this book has been concerned with meters for measuring total flow and flowrate in pipes. Quality measurement m vm these techniques are for the most part all used in classical fluid flows. Generally, the rotameter is a tube made of plastic, glass or metal combined with a float, which responds linearly to the flowrate of the fluid in that tube. This was the first recorded instrument to measure wind speed. Measurement in fluid mechanics measurement in fluid mechanics is an introductory, uptodate, general refer. Devices and methods for enabling measurement of a selected fluid characteristic in fluid flowing through a conduit. They are commonly used to measure air velocity, but can be use to measure the velocity of other fluids as well. Measurement of the density of a fluid and the relative density of a liquid using a hydrometer and a pycnometer.

Applications of bernoullis equation finding pressure. The measure of velocity depends on the scale of an object. When the position of a vehicle is determined with a periodic rate, computation of its velocity is no problem. Pressure drop devices based on bernoulli principle a venturi. The flow past a cylinder of arbitrary cross section and infinite length is an example of plane flow. The greater the head pressure, the faster the fluid flow rate all other factors remaining constant, and. Analysis and control of fluid flows, often subsidiary to industrial design issues, require measurements of the flow field. Fluid flow measurement flow measurement has a history of about 3000 years. For example, speed of a large object may be very efficiently determined by gps. This type of flow meter is one of the most sensitive to processing conditions. Industrialprocess measurement and control standards policy committee. Due to the sharpness of the contraction in flow area at the orifice plate a vena contracta is formed downstream of the throat in which the area of the vena contracta is less than that of the orifice.

Bernoullis equation is applied to fluid flow problems, under certain assumptions, to find unknown parameters of flow between any two points on a streamline. Pressure drop in piping, measuring device small appreciable. Theory overview of flow measurement using differential. The velocity which is the main result of flow measuring is prominent variable. Contactless fluidlevel measurement using a reflectometer. Us6868741b2 device and method enabling fluid characteristic. Fluid mechanics pdf notes fm pdf notes smartzworld. With the annubar, or multiorifice pitot probe, the dynamic pressure can be measured across the velocity profile, and the annubar obtains an averaging effect.

Because the equation is derived as an energy equation for ideal, incompressible, invinsid, and steady flow along streamline, it is applicable to such cases only. We come now to instruments of a related but essentially. The velocity profile of the fluid is also considerably altered by changes in the fluid viscosity. A dozen ways to measure fluid level and how they work. Venturi tube due to simplicity and dependability, the venturi tube flowmeter is often used in applications where its necessary with higher turn down rates, or lower pressure drops, than the orifice. Measuring instruments for fluid velocity, pressure and. Fluid flow measurement can encompass a wide variety of fluids and applications. Flow measurement is the quantification of bulk fluid movement. Industrial flow measurement industrial flow measurement. Pdf the basic operating principle of differential pressure flowmeter is based on the premise that the. Flow and fluid velocity flow measurement fluid dynamics.

Pitot tubes also called pitot static tubes are used to measure fluid velocity at a point in a fluid. Zahurul haq buet fluid flow measurement me 361 14 21 measurement of fluid v elocity most devices require that the. The earliest known uses for flow come as early as the first recorded history. Fluid level measurements can be accurately measured through the wall of a nonmetallic tank by placing an airdielectric transmission line up against the side of the tank and sensing the rf impedance. Iso 3966, measurement of fluid flow in closed conduits velocityarea method using pitotstatic tubes.

The pitot tube measures the fluid flow velocity by converting the kinetic energy of the flow into potential energy. The fluid density is also needed in order to determine fluid velocity. Note that in this context the word cylinder is used for describing any body whose shape is invariant along the length of the body. A pitot tube is a simple device meant for measuring the velocity of a liquid at any point. There are several types of flow measurement devices currently in use across the united states by private, local, state, and federal agencies. A measure for the internal friction is given by the dynamic viscosity for a sphere of radius r moving at velocity vin an infinitely extended fluid of dynamic viscosity. A pitot tube can be used to measure fluid flow velocity by converting the kinetic energy in a fluid flow to potential energy. Apr 22, 2020 velocity flow meters are commonly used in industries because they provide a nonstop measurement of fluid velocity. Omega laboratory rotameters are far more versatile due to the use they make of correlation equations. Applications of bernoullis equation finding pressure, velocity. Acceleration is a dynamic characteristic of an object. There are some examples of fluids for which glass tubes cannot be used.

Pressure measurement techniques transducers manometer, diaphragm, piezoelectric probes tap, standard, other devices velocity measurement techniques pitotstatic probe hotwire anemometry laser. Stokes derived an expression for the frictional force. Consists of two concentrically arranged tubes bent at right. The demands of sophisticated automated processing systems, the need for evertighter process control, and an increasingly stringent regulatory environment drive process engineers to seek more precise and reliable level measurement systems. Fluid velocity at the turbine must be greater than turbine blade velocity at the inlet for the device to act as a turbine and generate power. In the venturi tube the fluid flowrate is measured by reducing the cross sectional flow area in the flow path, generating a pressure difference. Fluid mechanics notes pdf fm notes pdf starts with the topics covering introduction to dimensions and units physical properties of fluids specific gravity, viscosity, surface tension. The influence that fluid viscosity exerts on the velocity profile is best defined using the reynolds number re, the dimensionless ratio of inertial forces to viscous forces in a flowing fluid. After the constricted area, the fluid is passes through a pressure recovery exit section, where up to 80% of the differential pressure generated at the constricted area. We come now to instruments of a related but essentially different type, namely instruments for measuring the velocity at a point of a flowing fluid.

Liquid velocity measurement meters function under the theory that there is a constant velocity profile. An english inventor, robert hooke reinvented this device in 1709, along with the mayan. Calculate fluid flow and pipe velocities in a suction or discharge of a pump. Nov 23, 2010 part 1 of the third fluids lecture as part of the module thermodynamics and fluids ufmequ201, given on 081110. One of the two sensors is constantly heated and the cooling effect of the flowing fluid is used to monitor the flowrate. Vapor pressure and their influences on fluid motion pressure at a point, pascals law, hydrostatic law, etc. Part 1 of the third fluids lecture as part of the module thermodynamics and fluids ufmequ201, given on 081110. This difference, called the dynamic pressure, can be used to calculate the fluid velocity at the point of measurement. In its simple form the pitot tube consists of a glass tube whose lower end is bent at right angles fig. Differential pressure flow instruments create a differential pressure in a fluid. In problems where the pressure and elevation at two points and velocity at one point is known, and we have to find the unknown velocity, bernoullis equation is applied to calculate the required velocity. An internet book on fluid dynamics introduction to flow rate and velocity measurement there are numerous ways of measuring. Water over 90c 194f, with its high ph which softens glass. The following points highlight the five main types of devices for measuring of flow in pipes.

Velocity flow meters are commonly used in industries because they provide a nonstop measurement of fluid velocity. What characteristics should measurement devices have. These transport terms were derived from the navierstokes equations by introducing into the equation mean velocity components and turbulent velocity fluctuation, and by averaging them afterwards with respect to time. Some of these methods are focussed on measuring the total flow rate in a pipe or other device while others are designed to measure the flow velocity at a. Siphon is used to drain a fluid from a reservoir at a higher level to a lower. Are the up stream velocity and viscosity of the fluid. Fluid velocity depends on the head pressure which is forcing the fluid through the pipe. The flow measuring apparatus is used to familiarize the students with typical methods of flow measurement of an incompressible fluid and, at the same time demonstrate applications of the bernoullis equation. In a differential pressure drop device the flow is calculated by measuring the. Mar 16, 2018 depending on the chemical characteristics of the measurement fluid, plastic or metal endcaps can be used. In velocity measurement, a sensor which is made of a glass capillary tube 3040.

A dozen ways to measure fluid level and how they work level. Measurement in fluid mechanics also features extensive background materials in system response, measurement uncertainty, signal analysis, optics. In general we can split the fluids into two classes. The actual velocity of the fluid at a given point measured in metres per second. This article describes different measurements which are available to measure velocity and to measure fluid pressure and wave height. Contactless fluidlevel measurement using a reflectometer chip.

Pdf velocity measurement techniques for liquid metal flows. The principle is based on the bernoulli equation where each term of the equation can be interpreted as pressure. Measurement of the viscosity of a fluid using a sphere viscometer. The flow conditioner section includes a straight, substantially constant diameter conduit. Measurement in fluid mechanics is an introductory, uptodate, general reference in experimental fluid mechanics, describing both classical and stateoftheart methods for flow visualization and for measuring flow rate, pressure, velocity, temperature, concentration, and wall shear stress. The fluid flow meter may collect measurement signals from one or more flow sensors e. A second scale is provided on the other side of the meter to read static pressure in inches w. The pitot tube is used to measure the difference between stagnation pressure and static pressure at a point in the fluid. The common types of flowmeters with industrial applications are listed below. Contactless fluid level measurement using a reflectometer chip. Fluid velocity measurement using a pitot tube pitot. To meet this wide variety of applications the instrumentation industry has, over many years, developed a wide variety of instruments.

A fluid flow meter estimates the velocity of water or another fluid flowing through pipe by comparing measurements of the water velocity to one or more predetermined templates. Measurement of the atmospheric pressure using a barometer. Apr 30, 2016 fluid mechanics flow measuring devices created by. Introduction to fluidflow measurement springerlink. Fluid velocity measurement using a pitot tube pitot static. It has been studied only in the last 200 years and in the last 30 years all the new techniques have evolved. Some of these methods are focussed on measuring the total. The device includes a body connected in the conduit having an accelerator section and a flow conditioner section within which a measuring unit such as an averaging pitot is maintained. Rotameter flow meters are devices that can measure the flowrate of liquids and gases. For classical transparent fluids such as water or gas a variety of well.

The calorimetric principle for fluid flow measurement is based on two temperature sensors in close contact with the fluid but thermal insulated from each other. Fluid velocity measuring instruments and insertion meters. The use of the pitot tube is restricted to point measuring. In its simplest form, the device consists of a short converging section leading to a throat and followed by a diverging. Illustrating the effects of fluid velocity this example shows what happens to the pressure level inside a hose assembly as the pressurecontrol device response and fluid bulk flow velocity vary. Flow measurement has a history of about 3000 years. Optical techniques laser doppler single phase flows two phase flows 1.