What is doppler flow meter?
Doppler circulate meter is a sort of ultrasonic circulate meter. These units use the scientific precept of the Doppler impact to measure the volumetric flow through a pipe. This is completed in such a means that the Doppler circulate meter is clamped to the surface of the pipe, so it does not disturb the circulate as other forms of circulate meters require.
Doppler flow meters use the frequency of the ultrasonic beam to determine the circulate rate of a liquid. This measurement is feasible because of the Doppler impact found by Austrian scientist Christian Johann Doppler in the early 1800s. Essentially, the Doppler effect means 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 by 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 should comprise particles or bubbles, so it really works properly for dirty liquids, however not so well for clear water. The move meter emits an ultrasonic sign, which is mirrored by particles and bubbles, resulting in 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 flow price. The velocity of flow within the pipe is calculated using the frequency shift, the unique frequency of the ultrasonic sign, the speed of the sound via the emitter materials, and the sine of the angle of the signal into the liquid. Once the velocity is thought, the volumetric circulate price may be simply calculated by multiplying the rate by the realm of the pipe.
In calculating the circulate price, the meter detects the rate at the discontinuity, not the velocity of the fluid. The velocity of flow (V) may be determined by the following equation.
V = (f zero – f 1 )Ct / 2f zero cos(a)
where Ct is the pace 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 0 cos(a) is a continuing (K), the connection could be simplified to
V = (f 0 – f 1 )K
Thus, the circulate fee V (ft/sec) is proportional to the change in frequency. The circulate rate (Q in gpm) in a pipe with a specific inner diameter (ID in.) may be obtained by the following equation
Q = 2.45V(ID) 2 = 2.45f 0 -f 1 )K 2
The presence of acoustic discontinuities is important to the right operation of a Doppler circulate meter. The usually accepted rule of thumb is that for correct signal reflection, at least 80-100 mg/l of solid particles are +200 mesh (+75 microns) in size. In the case of bubbles, a diameter of 100-200 mg/l between +75 and +150 microns is good. If the dimensions or concentration of the discontinuity adjustments, the amplitude of the reflected signal might be shifted, introducing errors.
Doppler flowmeters might have one or two sensors. Both varieties include a transmitter and a receiver, but in a single sensor Doppler move meter they’re contained in a single sensor. Reflected particles within the liquid replicate the transmitted sign again to the receiver. In a twin sensor circulate meter, the transmitter and receiver are sandwiched on opposite sides of the pipe.
Doppler flow meters could be a good monitoring possibility as a end result of they do not intervene with move and require little upkeep. In addition, they will present quick and correct circulate measurements for a variety of liquids beneath a wide selection of temperature and move situations. On the other hand, liquids must contain air bubbles or particles for the meter to work properly, and lined or chrome steel piping can intrude with the transmitter sign and reduce measurement accuracy.
Advantages of Doppler ultrasonic flow meters
Doppler circulate meters can be utilized where different meters don’t work. This could additionally 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 move
Can be installed outdoors the pipe
Pressure drop equal to the equal size of a straight pipe1
Low circulate cut-off
Corrosion resistance
Relatively low power consumption
Extended reading:
Ultrasonic circulate meter working principle
Select the proper water circulate meter
Mass circulate rate vs volumetric circulate price
Relation between flow and straine
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What is doppler circulate meter?
Doppler circulate meter is a sort of ultrasonic flow meter. These units use the scientific precept of the Doppler impact to measure the volumetric flow by way of a pipe. This is completed in such a way that the Doppler circulate meter is clamped to the surface of the pipe, so it does not disturb the flow as other types of move meters require.
Doppler move meters use the frequency of the ultrasonic beam to discover out the circulate rate of a liquid. This measurement is feasible because of the Doppler effect discovered by Austrian scientist Christian Johann Doppler in 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 by way of which the sound travels. In this case, the medium during 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 should comprise particles or bubbles, so it works nicely for dirty liquids, but not so well for clean water. The move meter emits an ultrasonic signal, which is mirrored by particles and bubbles, leading to 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 into a volumetric circulate rate. The velocity of circulate within the pipe is calculated utilizing the frequency shift, the original frequency of the ultrasonic sign, the rate of the sound via the emitter materials, and the sine of the angle of the sign into the liquid. Once the rate is known, the volumetric flow price may be easily calculated by multiplying the rate by the area of the pipe.
In calculating the move price, the meter detects the velocity at the discontinuity, not the rate of the fluid. The velocity of circulate (V) could be determined by the next equation.
V = (f 0 – f 1 )Ct / 2f 0 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 0 cos(a) is a constant (K), the connection can be simplified to
V = (f zero – f 1 )K
Thus, the move rate V (ft/sec) is proportional to the change in frequency. The move rate (Q in gpm) in a pipe with a selected internal diameter (ID in.) could be obtained by the next equation
Q = 2.45V(ID) 2 = 2.45f 0 -f 1 )K 2
The presence of acoustic discontinuities is critical to the proper operation of a Doppler circulate meter. The typically accepted rule of thumb is that for correct signal reflection, a minimal of 80-100 mg/l of solid particles are +200 mesh (+75 microns) in size. In the case of bubbles, a diameter of 100-200 mg/l between +75 and +150 microns is ideal. If the size or concentration of the discontinuity changes, the amplitude of the mirrored signal shall be shifted, introducing errors.
Doppler flowmeters might have one or two sensors. Both varieties include a transmitter and a receiver, however in a single sensor Doppler flow meter they’re contained in one sensor. Reflected particles within the liquid mirror the transmitted sign again to the receiver. In a twin sensor circulate meter, the transmitter and receiver are sandwiched on reverse sides of the pipe.
Doppler move meters is often a good monitoring choice as a result of they do not intervene with circulate and require little maintenance. In addition, they will provide quick and correct circulate measurements for a variety of liquids beneath a variety of temperature and move conditions. On the opposite hand, liquids should include air bubbles or particles for the meter to work correctly, and lined or chrome steel piping can interfere with the transmitter sign and cut back measurement accuracy.
Advantages of Doppler ultrasonic circulate meters
Doppler circulate meters can be utilized the place other meters do not work. This could also be liquid slurries, aerated liquids or liquids containing small or giant amounts of suspended solids. The advantages can be summarized as follows.
Less obstruction to circulate
Can be installed exterior 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 flow meter working principle
Select the best water circulate meter
Mass circulate fee vs volumetric flow price
Relation between circulate and pressuree