What is doppler flow meter?
Doppler circulate meter is a type of ultrasonic move meter. These devices use the scientific principle of the Doppler effect to measure the volumetric move through a pipe. This is done in such a means that the Doppler circulate meter is clamped to the surface of the pipe, so it doesn’t disturb the circulate as other kinds of flow meters require.
Doppler circulate meters use the frequency of the ultrasonic beam to find out the move fee of a liquid. This measurement is feasible due to the Doppler impact discovered by Austrian scientist Christian Johann Doppler in the early 1800s. Essentially, the Doppler impact suggests that the frequency of a sound wave is decided by the motion of the sound receiver, or the source of the sound relative to the medium via which the sound travels. In this case, the medium during which the sound wave propagates is the liquid flowing via the pipe.
In order for a Doppler flowmeter to work correctly, the liquid should comprise particles or bubbles, so it actually works nicely for dirty liquids, however not so nicely for clear water. The flow meter emits an ultrasonic sign, which is reflected 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 right into a volumetric circulate rate. The velocity of flow in the pipe is calculated using the frequency shift, the unique frequency of the ultrasonic sign, the velocity of the sound via the emitter material, and the sine of the angle of the sign into the liquid. Once the speed is understood, the volumetric circulate fee may be simply calculated by multiplying the rate by the area of the pipe.
In calculating the circulate fee, the meter detects the velocity at the discontinuity, not the speed of the fluid. The velocity of flow (V) could be decided by the next equation.
V = (f 0 – f 1 )Ct / 2f 0 cos(a)
where Ct is the speed 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 relationship may be simplified to
V = (f zero – f 1 )K
Thus, the circulate rate V (ft/sec) is proportional to the change in frequency. The flow rate (Q in gpm) in a pipe with a selected inner diameter (ID in.) could be obtained by the following equation
Q = 2.45V(ID) 2 = 2.45f 0 -f 1 )K 2
The presence of acoustic discontinuities is crucial to the proper 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 dimension. In the case of bubbles, a diameter of 100-200 mg/l between +75 and +150 microns is ideal. If the dimensions or concentration of the discontinuity changes, the amplitude of the reflected sign shall be shifted, introducing errors.
Doppler flowmeters may have one or two sensors. Both sorts include a transmitter and a receiver, however in a single sensor Doppler circulate meter they’re contained in one 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 reverse sides of the pipe.
Doppler circulate meters could be a good monitoring choice as a end result of they do not intervene with circulate and require little upkeep. In addition, they can provide quick and accurate move measurements for a wide range of liquids beneath a wide selection of temperature and flow situations. On the other hand, liquids should contain 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 move meters
Doppler move meters can be utilized the place different meters do not work. This could additionally be liquid slurries, aerated liquids or liquids containing small or large quantities of suspended solids. The advantages could be summarized as follows.
Less obstruction to flow
Can be installed outdoors the pipe
Pressure drop equal to the equivalent length of a straight pipe1
Low flow cut-off
Corrosion resistance
Relatively low energy consumption
Extended studying:
Ultrasonic circulate meter working precept
Select the proper water move meter
Mass circulate rate vs volumetric circulate rate
Relation between move and stresse
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What is doppler flow meter?
Doppler circulate meter is a kind of ultrasonic circulate meter. These devices use the scientific precept of the Doppler effect to measure the volumetric move through a pipe. This is completed in such a method that the Doppler move meter is clamped to the outside of the pipe, so it doesn’t disturb the circulate as other kinds of move meters require.
Doppler circulate meters use the frequency of the ultrasonic beam to determine the move fee of a liquid. This measurement is possible as a end result of Doppler impact found by Austrian scientist Christian Johann Doppler within the early 1800s. Essentially, the Doppler impact suggests that the frequency of a sound wave is determined by the motion of the sound receiver, or the source of the sound relative to the medium through which the sound travels. In this case, the medium in which the sound wave propagates is the liquid flowing through the pipe.
In order for a Doppler flowmeter to work correctly, the liquid should comprise particles or bubbles, so it works well for dirty liquids, however not so properly for clear water. The move meter emits an ultrasonic sign, which is reflected 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 circulate fee. 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 materials, and the sine of the angle of the signal into the liquid. Once the rate is understood, the volumetric circulate fee could be simply calculated by multiplying the rate by the area of the pipe.
In calculating the flow rate, the meter detects the rate at the discontinuity, not the speed of the fluid. The velocity of move (V) can be decided by the next equation.
V = (f 0 – f 1 )Ct / 2f zero cos(a)
where Ct is the speed 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 continuing (K), the connection may be simplified to
V = (f zero – f 1 )K
Thus, the flow price V (ft/sec) is proportional to the change in frequency. The move price (Q in gpm) in a pipe with a specific inside diameter (ID in.) can be obtained by the following equation
Q = 2.45V(ID) 2 = 2.45f 0 -f 1 )K 2
The presence of acoustic discontinuities is crucial to the proper operation of a Doppler circulate meter. The typically accepted rule of thumb is that for correct signal reflection, no much less than 80-100 mg/l of strong particles are +200 mesh (+75 microns) in measurement. In the case of bubbles, a diameter of 100-200 mg/l between +75 and +150 microns is ideal. If the size or focus of the discontinuity modifications, the amplitude of the reflected sign will be shifted, introducing errors.
Doppler flowmeters could have one or two sensors. Both varieties comprise a transmitter and a receiver, however in a single sensor Doppler circulate meter they are contained in a single sensor. Reflected particles within the liquid replicate the transmitted signal again to the receiver. In a twin sensor move meter, the transmitter and receiver are sandwiched on opposite sides of the pipe.
เกจ์ออกซิเจนsumo can be a good monitoring choice as a end result of they don’t intervene with move and require little upkeep. In addition, they can present fast and accurate move measurements for a variety of liquids underneath a wide selection of temperature and move circumstances. On the opposite hand, liquids should include air bubbles or particles for the meter to work correctly, and lined or chrome steel piping can intrude with the transmitter sign and cut back measurement accuracy.
Advantages of Doppler ultrasonic circulate meters
Doppler flow meters can be used where other meters don’t work. This may be liquid slurries, aerated liquids or liquids containing small or large quantities of suspended solids. The benefits can 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 flow cut-off
Corrosion resistance
Relatively low power consumption
Extended studying:
Ultrasonic circulate meter working principle
Select the right water flow meter
Mass flow rate vs volumetric move fee
Relation between circulate and stresse