What is doppler flow meter?
Doppler move meter is a type of ultrasonic circulate meter. These gadgets use the scientific precept of the Doppler effect to measure the volumetric circulate via a pipe. This is finished in such a means that the Doppler move meter is clamped to the outside of the pipe, so it does not disturb the move as other types of move meters require.
Doppler flow meters use the frequency of the ultrasonic beam to discover out the move fee of a liquid. This measurement is possible because of the Doppler effect found by Austrian scientist Christian Johann Doppler within the early 1800s. Essentially, the Doppler impact suggests that the frequency of a sound wave is dependent upon the movement of the sound receiver, or the supply of the sound relative to the medium via which the sound travels. In this case, the medium in which the sound wave propagates is the liquid flowing by way of the pipe.
In order for a Doppler flowmeter to work correctly, the liquid must include particles or bubbles, so it really works properly for dirty liquids, however not so properly for clean water. The flow meter emits an ultrasonic sign, which is reflected by particles and bubbles, resulting in a shift in signal frequency. This frequency shift is measured by the flowmeter.
How does doppler flowmeter work?
The Doppler flowmeter converts the measured frequency shift right into a volumetric circulate price. The velocity of circulate in the pipe is calculated using the frequency shift, the original frequency of the ultrasonic signal, the speed of the sound by way of the emitter materials, and the sine of the angle of the sign into the liquid. Once the rate is thought, the volumetric move fee could be easily calculated by multiplying the velocity by the world of the pipe.
In calculating the move fee, the meter detects the velocity on the discontinuity, not the velocity of the fluid. The velocity of flow (V) may be determined by the next equation.
V = (f 0 – f 1 )Ct / 2f zero cos(a)
where Ct is the velocity of sound contained in the transducer, f0 is the transmission frequency, f1 is the reflection frequency, and a is the angle of the transmitter and receiver crystals with respect to the tube axis. Since C t / 2f zero cos(a) is a continuing (K), the connection could be simplified to
V = (f zero – f 1 )K
Thus, the move rate V (ft/sec) is proportional to the change in frequency. The flow rate (Q in gpm) in a pipe with a particular internal diameter (ID in.) may be obtained by the following equation
Q = 2.45V(ID) 2 = 2.45f zero -f 1 )K 2
The presence of acoustic discontinuities is important to the proper operation of a Doppler move meter. The generally accepted rule of thumb is that for proper signal reflection, at least 80-100 mg/l of stable particles are +200 mesh (+75 microns) in dimension. In the case of bubbles, a diameter of 100-200 mg/l between +75 and +150 microns is ideal. If the scale or focus of the discontinuity changes, the amplitude of the mirrored sign might be shifted, introducing errors.
Doppler flowmeters may have one or two sensors. Both types contain a transmitter and a receiver, but in a single sensor Doppler circulate meter they’re contained in a single sensor. Reflected particles within the liquid replicate the transmitted sign back to the receiver. In a twin sensor move meter, the transmitter and receiver are sandwiched on opposite sides of the pipe.
Doppler flow meters is often a good monitoring choice as a outcome of they do not intervene with move and require little upkeep. In addition, they will provide quick and correct circulate measurements for a wide range of liquids underneath a selection of temperature and move conditions. On the opposite hand, liquids must include air bubbles or particles for the meter to work properly, and lined or stainless-steel piping can intervene with the transmitter signal and reduce measurement accuracy.
Advantages of Doppler ultrasonic flow meters
Doppler move meters can be utilized where different meters don’t work. This may be liquid slurries, aerated liquids or liquids containing small or large quantities of suspended solids. The advantages may be summarized as follows.
Less obstruction to move
Can be put in outdoors the pipe
Pressure drop equal to the equivalent size of a straight pipe1
Low circulate cut-off
Corrosion resistance
Relatively low power consumption
Extended reading:
Ultrasonic flow meter working principle
Select the proper water flow meter
Mass circulate price vs volumetric move price
Relation between circulate and pressuree
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What is doppler circulate meter?
Doppler circulate meter is a type of ultrasonic flow meter. These devices use the scientific precept of the Doppler effect to measure the volumetric circulate through a pipe. This is completed in such a way that the Doppler move meter is clamped to the skin of the pipe, so it doesn’t disturb the circulate as different kinds of move meters require.
Doppler flow meters use the frequency of the ultrasonic beam to determine the move price of a liquid. This measurement is feasible as a result of Doppler impact found by Austrian scientist Christian Johann Doppler in the early 1800s. Essentially, the Doppler effect suggests that the frequency of a sound wave is decided by the movement of the sound receiver, or the supply of the sound relative to the medium by way of which the sound travels. In this case, the medium during which the sound wave propagates is the liquid flowing through the pipe.
In order for a Doppler flowmeter to work properly, the liquid should include particles or bubbles, so it works well for soiled liquids, but not so properly for clean water. The circulate meter emits an ultrasonic signal, which is mirrored by particles and bubbles, leading to a shift in sign frequency. This frequency shift is measured by the flowmeter.
How does doppler flowmeter work?
The Doppler flowmeter converts the measured frequency shift into a volumetric move rate. The velocity of move in the pipe is calculated using the frequency shift, the original frequency of the ultrasonic sign, the velocity of the sound through the emitter material, and the sine of the angle of the signal into the liquid. Once the velocity is known, the volumetric move price may be simply calculated by multiplying the speed by the realm of the pipe.
In calculating the flow price, the meter detects the rate on the discontinuity, not the velocity of the fluid. The velocity of circulate (V) can be determined by the next equation.
V = (f zero – f 1 )Ct / 2f 0 cos(a)
where Ct is the pace of sound inside the transducer, f0 is the transmission frequency, f1 is the reflection frequency, and a is the angle of the transmitter and receiver crystals with respect to the tube axis. Since C t / 2f 0 cos(a) is a constant (K), the relationship may be simplified to
V = (f 0 – f 1 )K
Thus, the flow fee V (ft/sec) is proportional to the change in frequency. The flow rate (Q in gpm) in a pipe with a particular inner diameter (ID in.) can be obtained by the next equation
Q = 2.45V(ID) 2 = 2.45f 0 -f 1 )K 2
The presence of acoustic discontinuities is important to the correct operation of a Doppler circulate meter. The typically accepted rule of thumb is that for correct signal reflection, at least 80-100 mg/l of strong particles are +200 mesh (+75 microns) in dimension. In the case of bubbles, a diameter of 100-200 mg/l between +75 and +150 microns is right. If the size or focus of the discontinuity changes, the amplitude of the reflected sign might be shifted, introducing errors.
Doppler flowmeters may have one or two sensors. Both varieties contain a transmitter and a receiver, but in a single sensor Doppler move meter they’re contained in one sensor. Reflected ส่วนประกอบpressuregauge within the liquid replicate the transmitted signal again to the receiver. In a twin sensor circulate meter, the transmitter and receiver are sandwiched on reverse sides of the pipe.
Doppler circulate meters is normally a good monitoring possibility as a result of they do not interfere with move and require little maintenance. In addition, they can provide fast and accurate circulate measurements for a variety of liquids beneath a variety of temperature and circulate circumstances. On the other hand, liquids must include air bubbles or particles for the meter to work properly, and lined or stainless-steel piping can intervene with the transmitter signal and cut back measurement accuracy.
Advantages of Doppler ultrasonic flow meters
Doppler move meters can be utilized the place other meters don’t work. This could also be liquid slurries, aerated liquids or liquids containing small or giant amounts of suspended solids. The advantages could be summarized as follows.
Less obstruction to circulate
Can be put in outside the pipe
Pressure drop equal to the equivalent size of a straight pipe1
Low circulate cut-off
Corrosion resistance
Relatively low energy consumption
Extended reading:
Ultrasonic move meter working principle
Select the proper water move meter
Mass flow price vs volumetric circulate rate
Relation between circulate and stresse