Doppler shift ow meters [edit edit]] Another method in ultrasonic fow metering is the use o the Doppler shit that shit that results rom the refection o an ultrasonic beam o sonically refective refective materials, materials, such as solid particles or entrained air bubbles in bubbles in a fowing fuid, or the turbulence turbulence o o the fuid itsel, i the liquid is clean. Doppler fowmeters are used or slurries slurries,, liquids with bubbles, gases with soundrefecting soundrefecting particles. !his type o fow meter can can also be used to measure the rate o blood blood fow, fow, by passing an ultrasonic beam through the tissues, bouncing it o a refective refective plate, then reversing reversing the direction o the beam and repeating the measurement, measurement, the volume o blood blood fow fow can be estimated. !he requency o the transmitted beam is aected by the movement o blood in the vessel and by comparing the requency o the upstream beam versus downstream the fow o blood through the vessel can be measured. !he dierence between the two requencies is a measure o true volume fow. A widebeam sensor can also be used us ed to measure fow independent o the crosssectional area o the blood vessel.
DFX Doppler Ultrasonic Flow Meters The DFX ultrasonic Doppler ow meter measures ows of liquids containing suspended particles or aerated liquids. The suspended particles must reect ultrasonic energy. The DFX ow meter operates by transmitting ultrasonic ultrasonic waves into the ow stream and
measuring the frequency shift of the reected wave. The meters clamp!on design allows quic" and low!cost installation# and eliminates worries of uid compatibility and pressure head loss. $ith no moving parts# there is no mechanical wear# so repair "its or replacement parts are not needed. %ement slurry# a mi&ture of cement# water# and assorted dry and liquid additives used in the petroleum and other industries'()'*) +oil,cement slurry# also called %ontrolled -ow!+trength Material %-+M/# owable 0ll# controlled density 0ll# owable mortar# plastic soil!cement# 1!1rete# and other names '2) 3 mi&ture of thic"ening agent# o&idi4ers# and water used to form a gel e&plosive'citation needed ) 3 mi&ture of pyroclastic material# roc"y debris# and water produced in a volcanic eruption and "nown as a How Ultrasonic Flowmeters Work •
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Ultrasonic flowmeters use sound waves to determine the velocity of a fluid flowing in a pipe. At no flow conditions, the frequencie s of an ultrasonic wave transmitted into a pipe and its reflections from the fluid are the same. Under flowing conditions, the frequency of the reflected wave is different due to the Doppler effect. When the fluid moves faster, the frequency sh ift increases linearly. The transmitter processes signals from the transmitted wave and its reflections to determine the flow rate. Transit time ultrasonic flowmeters send and receive ultrasonic waves between transducers in both the upstream and downstream directions in the pipe. At no flow conditions, it takes the same time to travel upstream and downstream between the transducers. Under flowing conditions, the upstream wave will travel slower and take more time than the faster! downstream wave. When the fluid moves faster, the difference between the upstream and d ownstream times increases. The transmitter processes upstream and downstream times to determine the flow rate. They represent about "#$ of all flowmeters sold. Plusses and Minuses
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This technology can be very accurate and is used for custody transfer meaning accounting accurately for an e%pensive fluid! of natural gas and petroleum liquids. &igh turndown can read low as a percentage of the full scale or top reading!, handles high pressures, is repeatable consistent!, handles e%treme temperatures, can be used clamped to the outside of a pipe without penetration, is low maintenance, highly reliable and self 'diagnosing. Disadvantages can
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include high cost, sensitivity to stray process vibrations, problems with pipe diameter change due to buildup and clamp(on units have lower accuracy. Ultrasonic flowmeters do not obstruct flow so they can be applied to sanitary, corrosive and abrasive liquids. )ome ultrasonic flowmeters use clamp(on transducers that can be mounted e%ternal to the pipe and do not have any wetted parts. Temporary flow measurements can be made using portable ultrasonic flowmeters with clamp(on transducers. *lamp(on transducers are especially useful when piping cannot be disturbed, such as in power and nuclear industry applications. +n addition, clamp(on transducers can be used to measure flow without regard to materials of construction, corrosion, and abrasion issues. &owever attractive, the use of clamp(on transducers introduces additional ultrasonic interfaces that can affect the reliability and performance of these flowmeters. +n particular, if not properly applied and maintained, attenuation of the ultrasonic signal can occur at the interfaces between the clamp(on transducers and the outside pipe walls, and between the inside pipe walls and the fluid. Ultrasonic flowmeters are available in sies to -# inches and larger. How to Use Ultrasonic Flowmeters
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Ultrasonic flowmeters are commonly applied to measure the velocity of liquids that allow ultrasonic waves to pass, such as water, molten sulfur, cryogenic liquids, and chemicals. Transit time designs are also available to measure gas and vapor flow. e careful because fluids that do not pass ultrasonic energy, such as many types of slurry, limit the penetration of ultrasonic waves into the fluid. +n Doppler ultrasonic flowmeters, opaque fluids can limit ultrasonic wave penetration too near the pipe wall, which can degrade accuracy and/or cause the flowmeter to fail to measure. Transit time ultrasonic flowmeters can fail to operate when an opaque fluid weakens the ultrasonic wave to such an e%tent that the wave does not reach the receiver. Industries Where Used
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The industries in order of higher to lower are oil and gas, water and wastewater, power, chemical, food and beverage, pharmaceutical, metals and mining, and pulp and paper. Application Cautions for Ultrasonic Flowmeters
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0or transit time ultrasonic flowmeters, be sure that the fluid can adequately conduct ultrasonic waves, because the flowmeter will not measure when the ultrasonic waves cannot penetrate the flow stream between the transducers. )imilarly, ultrasonic waves must be able to penetrate the fluid for Doppler flowmeters to operate accurately. When the fluid is relatively opaque and does not penetrate the fluid, Doppler flowmeters tend to measure the velocity of the fluid at or near the pipe wall, which can cause significant measurement error and/or cause the flowmeter to fail. 0or Doppler ultrasonic flowmeters, be sure that the fluid adequately reflects ultrasonic waves, because the flowmeter will not operate without a reflected ultrasonic signal. Depending upon design, reflections can occur due to small bubbles of gas in the flow stream or the presence of eddies in the flow stream. +f
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not already present in the flowing stream, generating these sources of reflection can be difficult in practice. 0ortunately, some combination of bubbles of gas and/or eddies are present in most applications. The velocity of the solid particles in slurry can be different than its liquid carrier fluid. e careful applying ultrasonic technology when the solid particles can become concentrated in one part of the flowing stream, such as in a horiontal pipe flowing at a relatively low velocity. e careful when applying Doppler ultrasonic flowmeters in slurry applications because the solid particles can produce strong signals that can cause the Doppler flowmeter to measure the velocity of the solids and not the velocity of the liquid. Avoid fluids that can coat wetted transducers or coat the pipe wall in front of non( wetted transducers because the flowmeter will not measure when the ultrasonic waves cannot enter the flow stream. e sure to maintain reliable clamp(on transducer connections to the pipe wall because the flowmeter will not measure when the ultrasonic waves are not able to reach the fluid. e sure to understand the process and apply these flowmeters properly. 0or e%ample, a periodic cleaning process upstream may cause the flowmeter to stop working because the dirt may not allow ultrasonic energy to pass through the fluid. 0urther, if the dirt coats wetted transducers, the flowmeter may fail to operate until it is cleaned.
Open Channel Measures flow by measuring the height of the fluid as it passes over an obstruction in an open channel. Open channels may include flumes, a specially shaped open channel flow section with an area or slope that is different from that of the channel and weirs, a dam built across an area that the liquid flows over. Each type and structure will have an associated equation for determining the flow rate.
Ultrasonic The most commonly used technique of measuring the rate of flow in an open channel is that of hydraulic structures. Flow in an open channel is measured by inserting a hydraulic structure into the channel, which changes the level of the liquid in or near the structure. y selecting the shape and dimensions of the hydraulic structure, the rate of flow through or over the restriction will be related to the liquid level in a !nown manner. Therefore, the flow rate through an open channel can be derived from a single measurement of the liquid level.
"ydraulic structures used in measuring flow in open channels are !nown as primary measuring devices and are divided into two categories# flumes and
weirs. • • • • •
Uniform and reliable flow measurement data. $ids in meeting water quality regulatory requirements. Easy to install. %equires minimal maintenance. &on'contact system so is not affected by grease, suspended solids, silt, corrosive chemicals or liquid temperature fluctuations.
Hydraulic structure 0rom Wikipedia, the free encyclopedia
A hydraulic structure is a structure submerged or partially submerged in any body of water, which disrupts the natural flow of water. They can be used to divert, disrupt or completely stop the flow. An e%ample of a hydraulic structure would be a dam, which slows the normal flow rate of the river in order to power turbines. A hydraulic structure can be built in rivers, a sea, or any body of water where there is a need for a change in the natural flow of water.1"2 &ydraulic structures may also be used to measure the flow of water. When used to measure the flow of water, hydraulic structures are defined as a class of specially shaped, static devices over or through which water is directed in such a way that under free(flow conditions at a specified location point of measurement! a known level to flow relationship e%ists. Hydraulic structures of this type can generally be divided into two categories3 flumes and weirs
&ydraulic )tructures +n general, a hydraulic structure is anything that can be used to divert, dam, restrict, or otherwise manage the flow of open channel waters. 0or flow measurement purposed, a hydraulic structure is a fi%ed geometry device that is placed into the flow so that all of the flow is directed through or over the device. The device produces a characteried relationship between the liquid level in flumes! or upstream weirs! of the device and the flow rate at a single, defined location under free(flow conditions. Under submerged flow conditions, a second, downstream point of measurement must also be used. The free(flow point of measurement is termed the &a location, while the secondary, downstream point of measurement used for submerged flow measurement is termed the &b location. As a hydraulic structure directly produces a characteried relationship
between level and flow, it is termed a primary device. When the liquid level generated by the hydraulic structure is measured by an additional device, that device or flow meter! is termed the secondary device. &ydraulic structures can generally be divided into two categories3 flumes and weirs. 0lumes are more adaptable in their siing, configurations, and installation, while weirs, on channels capable of developing a proper weir pools, tend to be less e%pensive. 4f the two, weirs show greater laboratory accuracy 5/(#(6$! than flumes 5/(#(7$!, although in practice and under field conditions, the total system accuracies tend to be similar at 5/("8$. 9odern mechanical float! and electronic flow meters secondary devices! allow for the continuous measurement of hydraulic structure flows. 0or applications where continuous measurement is not required or possible, head / level / staff gauges can be used to aid the operator in determining the flow rate through the use of published rating or discharge tables. ( )ee more at3 http3//www.openchannelflow.com/blog/article/methods(of(measuring(flows(in(open(
channels:sthash.sy;8vse<.dpuf
3rea!5elocity Method "easurement o the mean fow velocity #commonly by doppler or electromagnetic $eld% over a determined cross sectional area #the depth o which is determined by pressure transducer or ultrasonic sensor% yields the stream fow rate. &ecent tests perormed by the 'ureau o &eclamation ound that even in a controlled, laboratory environment, measurement error o ()*+ are possible. -nder $eld
conditions, this error can reasonably be assumed to greater than those observed in laboratory conditions. ee more at/ http/))www.openchannelfow.com)blog)article)methodsomeasuringfowsin openchannels0sthash.sy1+vse2.dpu
56-7%8T9,3:63 M6T;7D !his depends on measuring the average velocity o fow and the cross sectional area o the channel and calculating the fow rom/ 2#m3)s% 4 A#m5% 6 7#m)s% !he metric unit m3)s is reerred to as the cumec. 'ecause m3)s is a large unit, smaller fows are measured in litres per second #l)s%. A simple way to estimate the velocity is to measure the time ta8en or a foating ob1ect to travel a measured distance downstream. !he velocity is not the same at all places in the stream, being slower at the sides and bottom, and aster on the surace, as shown in 9igure 5+. !a8ing +.: o the surace velocity as measured by the foat gives an appro6imate value or the average velocity. Alternatively, the velocity can be measured below the surace by attaching a submerged weight to a foat. !he foat and weight move down the stream together at the velocity o the stream at the depth where the weight is suspended. At about hal the stream depth, the velocity is appro6imately the same as the average velocity or the whole stream. 9loat methods are only suitable or straight streams or canals where the fow is airly even and regular.
Another method is to pour into the stream a quantity o strongly coloured dye, and to measure the time or this to fow a measured distance downstream. !he dye should be added quic8ly with a sharp cuto, so that it travels downstream in a cloud. !he time is measured or the $rst and last o the dye to reach the downstream measuring point and an average o the two times is used to calculate the average velocity.
;n turbulent streams the cloud o dye is dispersed quic8ly and cannot be observed and measured, but other tracers can be used, either chemical or radioisotopes, in what is called the dilution method. A solution o the tracer o 8nown strength is added to the stream at a constant measured rate and samples are ta8en at points downstream. !he concentration o the sample ta8en downstream can be compared with the concentration o the added tracer and the dilution is a unction o the rate o fow which can be calculated. "ore accurate determination o velocity can be obtained by using a current meter. !he two main types are illustrated in 9igure 5*. !he conical cup type revolves about a vertical a6is, and the propeller type about a horihen measurements o foodfows are to be measured on big rivers, the readings are ta8en either rom a bridge, or an overhead cableway is installed well above ma6imum food level, and the current meter is lowered on cables into the river with weights to hold it against the riverfow. A current meter measures the velocity at a single point, and several measurements are required to calculate the total fow. !he procedure is to measure and plot on graph paper the crosssection o the stream and to imagine that it is divided into strips o equal width as shown in 9igure 55. !he average velocity or each strip is estimated rom the mean o the velocity measured at +.5 and +.: o the depth in that strip. !his velocity, times the area o the strip, gives the fow or the strip and the total fow is the sum o the strips. !able 5 shows how the calculations will be done or data shown in 9igure 55. ;n practice, more strips would be used than the number shown in 9igure 55 and !able 5. 9or shallow water a single reading is ta8en at +.? o the depth instead o averaging the readings at +.5 and +.: o the depth. ometimes the inormation required on streamfow is the ma6imum food fow, and a rough estimate can be made using the velocity)area method. !he ma6imum depth o fow in a stream can sometimes be deduced rom the height o leaves and trash caught in vegetation on the ban8side, or rom the highest signs o scour or sediment deposits on the ban8. Alternatively some device can be installed which is designed to leave a record o the ma6imum level. !o prevent alse readings rom turbulence in the stream, some 8ind o stilling well is used usually a pipe with holes on the downstream side. !he
ma6imum depth o water can be recorded on a rod painted with a water soluble paint, or rom traces let at the highest level rom something foated on the water surace in the tube. "aterials used have included ground cor8, chal8 dust and ground charcoal. @nowing the ma6imum depth o fow, the corresponding crosssection area o the channel can be measured, and the velocity estimated by one o the methods described, bearing in mind that the velocity at high food will usually be aster than the normal fow.
Manning formula 0rom Wikipedia, the free encyclopedia
The Manning formula is also known as the GaucklerManning formula, or GaucklerManning !trickler formula in =urope. +n the United )tates, in practice, it is very frequently called simply Manning"s #$uation. The Manning formula is an empirical formula estimating the average velocity of a liquid flowing in a conduit that does not completely enclose the liquid, i.e., open channel flow. All flow in so(called open channels is driven by gravity. +t was first presented by the 0rench engineer >hilippe ?auckler in "@7-,1"2 and later re(developed by the +rish engineer obert 9anning in "@B8.1#2 The ?auckler'9anning formula states3
where3 •
V is the cross(sectional average velocity C/T ft/s, m/s!
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n is the GaucklerManning coefficient. Units for values of n are often left off, however it is
not dimensionless, having units of3 T/1C "/E2 s/1ft "/E2 s/1m"/E2!. •
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R h is the hydraulic radius C ft, m! S is the slope of the hydraulic grade line or the linear hydraulic head loss C/C!, which is the same as the channel bed slope when the water depth is constant. S F hf /L!. k is a conversion factor between )+ and =nglish units. +t can be left off, as long as you make
sure to note and correct the units in your GnG term. +f you leave GnG in the traditional )+ units, k is ;ust the dimensional analysis to convert to =nglish. kF" for )+ units, and kF".HB for =nglish units. Iote3 " m! "/E/s F E.#@8@EBB ft! "/E/s F ".H@6B ft "/E/s! I4T=3 Ks strickler F "/ n manning. The coefficient Ks strickler varies from #8 rough stone and rough surface! to @8 m"/E/s smooth concrete and cast iron!. The discharge formula, Q F A V , can be used to manipulate ?auckler'9anningJs equation by substitution for V . )olving for Q then allows an estimate of the volumetric flow ratedischarge! without knowing the limiting or actual flow velocity. The ?auckler'9anning formula is used to estimate the average velocity of water flowing in an open channel in locations where it is not practical to construct a weir or flume to measure flow with greater accuracy. The friction coefficients across weirs and orifices are less sub;ective
than n along a natural earthen, stone or vegetated! channel reach. *ross sectional area, as well as n' , will likely vary along a natural channel. Accordingly, more error is e%pected in estimating the average velocity by assuming a 9anningJs n, than by direct sampling i.e., with a current flowmeter!, or measuring it across weirs, flumes or orifices. 9anningJs equation is also commonly used as part of a numerical step method, such as the )tandard )tep 9ethod, for delineating the free surface profile of water flowing in an open channel. 1E2 The formula can be obtained by use of dimensional analysis. ecently this formula was derived theoretically using the phenomenological theory of turbulence.1H2
Hydraulic radius1edit2 The hydraulic radius is a measure of a channel flow efficiency. 0low speed along the channel depends on its cross(sectional shape among other factors!, and the hydraulic radius is a characterisation of the channel that intends to capture such efficiency. ased on the Jconstant shear stress at the boundaryJ assumption, 162 hydraulic radius is defined as the ratio of the channelJs cross(sectional area of the flow to its wetted perimeter the portion of the cross( sectionJs perimeter that is GwetG!3
where3 •
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R h is the hydraulic radius C! A is the cross sectional area of flow C #! P is the wetted perimeter C!.
The greater the hydraulic radius, the greater the efficiency of the channel and the more volume it can carry. 0or channels of a given width, the hydraulic radius is greater for the deeper channels. The hydraulic radius is not half the hydraulic diameter as the name may suggest. +t is a function of the shape of the pipe, channel, or river in which the water is flowing. +n wide rectangular channels, the hydraulic radius is appro%imated by the flow depth. The measure of a channelJs efficiency its ability to move water an d sediment! is used by water engineers to assess the channelJs capacity.
Gauckler–Manning coefficient 1edit2 The ?auckler'9anning coefficient, often denoted as n, is an empirically derived coefficient, which is dependent on many factors, including surface roughness and sinuosity. When field inspection is not possible, the best method to determine n is to use photographs of river channels where n has been determined using ?auckler'9anningJs formula. +n natural streams, n values vary greatly along its reach, and will even vary in a given reach of channel with different stages of flow. 9ost research shows that n will decrease with stage, at least up to bank(full. 4verbank n values for a given reach will vary greatly depending on the time of year and the velocity of flow. )ummer vegetation will typically have a significantly higher n value due to leaves and seasonal vegetation. esearch has shown, however, that n values are lower for individual shrubs with leaves than for the shrubs without leaves. 172 This is due to the ability of the plantJs leaves to streamline and fle% as the flow passes them thus lowering the resistance to flow. &igh velocity flows will cause some vegetation
such as grasses and forbs! to lay flat, where a lower velocity of flow through the same vegetation will not.1-2 +n open channels, the Darcy'Weisbach equation is valid using the hydraulic diameter as equivalent pipe diameter. +t is the only sound method to estimate the energy loss in man( made open channels. 0or various reasons mainly historical reasons!, empirical resistance coefficients e.g. *hKy, ?auckler'9anning')trickler! were and are still used. The*hKy coefficient was introduced in "-7@ while the ?auckler'9anning coefficient was first developed in "@76, well before the classical pipe flow resistance e%periments in the "B#8' "BE8s. &istorically both the *hKy and the ?auckler'9anning coefficients were e%pected to be constant and functions of the roughness onl y. ut it is now well recognised that these coefficients are only constant for a range of flow rates. 9ost friction coefficients e%cept perhaps the Darcy'Weisbach friction factor! are estimated 100% empirically and they apply only to fully rough turbulent water flows under steady flow conditions. 4ne of the most important applications of the 9anning equation is its use in sewer design. )ewers are often constructed as circular pipes. +t has lon g been accepted that the value of n varies with the flow depth in partially filled circular pipes. 1@2 A complete set of e%plicit equations that can be used to calculate the depth of flow and other unknown variables when applying the 9anning equation to circular pipes is available.1B2 These equations account for the variation of n with the depth of flow in accordance with the curves presented by *amp. "annings Bquation #Cauc8ler"anningtric8ler 9ormula% "annings Bquation, as it is commonly reerred to in the -nited tates, is an empirically derived ormula or estimating the average velocity o a liquid fowing in an open channel. !he ormula utili
Christian Doppler 0rom Wikipedia, the free encyclopedia This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and
removed. (April 2010)
Christian Doppler
29 November 1803
Born
al!burg" #ustria
1$ %arch 18&3 'aged (9)
Died
*enice" +taly
Nationality
#ustrian
Institutions
Prague Polytechnic #cademy o, %ines and -orests University o, *ienna
Known for
oppler e,,ect
Christian Andreas %oppler /FdGplLr/ #B Iovember "@8E ' "- 9arch "@6E! was an
Austrian mathematician and physicist. &e is celebrated for his principle M known as the Doppler effect M that the observed frequency of a wave depends on the relative speed of the source and the observer. &e used this concept to e%plain the color of binary stars. Contents
1hide2 •
"iography
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#0ull name
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E)ee also
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Heferences
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60urther reading
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7=%ternal links
Biography 1edit2 This section re/uires epansion. (May 2010)
Doppler was born and raised in )alburg, Austria, the son of a stonemason. &e could not work in his fatherJs business because of his generally weak physical condition. After completing high school, Doppler studied philosophy in )alburg and mathematics and physics at the k. k. Polytechnisches nstitut now Nienna University of Technology! where he began work as an assistant in "@#B. +n "@E6 he began work at the Pra!ue Polytechnic now *ech Technical University!, where he received an appointment in "@H".
DopplerJs birth house in )alburg, ;ust ne%t door to where 9oartJs family had lived. A Doppler research(and memorial society is now housed there.1"2
&ouse in >rague in which *hristian lived from "@HE to "@H-
4nly a year later, at the age of E@, Doppler gave a lecture to the oyal ohemian )ociety of )ciences and subsequently published his most notable work, GOber das farbige Cicht der Doppelsterne und einiger anderer ?estirne des &immelsG "#n the coloure$ li!ht of the inary stars an$ some other stars of the hea&ens . There is a facsimile edition with an =nglish translation by Alec =den.1#2 +n this work, Doppler postulated his principle later coined the Doppler effect! that the observed frequency of a wave depends on the relative speed of the source and the observer, and he tried to use this concept for e%plaining the colour of binary stars. +n DopplerJs time in>rague as a professor he published over 68 articles on mathematics, physics and astronomy. +n "@H- he left >rague for the professorship of mathematics, physics, and mechanics at the Academy of 9ines and 0orests its successor is the present day University of 9iskolc! in)elmecbPnya then Qingdom of &ungary, now anskP Rtiavnica, )lovakia!,1E21H2 and in "@HB he moved to Nienna. 162 DopplerJs research was interrupted by the revolutionary incidents of "@H@. During the &ungarian evolution, he fled to Nienna. There he was appointed head of the +nstitute for =%perimental >hysics at the University of Nienna in "@68. During his time there, Doppler, along with0ran Unger , played an influential role in the development of young ?regor 9endel, known as the founding father of genetics, who was a student at the University of Nienna from "@6" to "@6E. Doppler died on "- 9arch "@6E at age HB from a pulmonary disease in Nenice at that time part of the Austrian =mpire!. &is tomb, found by Dr. >eter 9. )chuster 172 is ;ust inside the entrance of the Nenetian island cemetery of )an 9ichele.1-2
Full name1edit2 )ome confusion e%ists about DopplerJs full name. Doppler referred to himself as *hristian Doppler. The records of his birth and baptism stated *hristian An$reas Doppler. 0orty years after DopplerJs death the misnomer (ohann *hristian Doppler was introduced by the astronomer Sulius )cheiner . )cheinerJs mistake has since been copied by many.1#2
