Acoustic Flow Sensor Using Density Modulation
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Solution Overview
Problem
Existing methods for determining flow properties of laminar flowing gases or liquids in pipelines are either sensitive to buildup and require frequent maintenance or are costly, such as thermal sensors and Coriolis meters.
Innovation Solution
A method involving a modulation element that temporarily changes the density of the medium, exciting a mechanically oscillatable unit to resonate, and converting these oscillations into electrical signals to determine flow properties like flow direction, speed, and mass flow rate, using a device with a heating element or limiting diameter configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal flow sensors are used to determine flow velocity, then measurement capability is provided, but the sensors are sensitive to build-up and exhibit thermal drift requiring frequent maintenance and recalibration
Solution Approach 1:
The patent replaces thermal measurement principles with acoustic measurement principles. Instead of using thermal sensors that heat the medium and measure temperature differences, the invention uses acoustic waves propagating through the medium to determine flow velocity by measuring the speed of sound, which is independent of thermal effects and build-up on sensors.
Solution Approach 2:
The patent introduces acoustic waves as an intermediary to indirectly measure flow velocity. Rather than directly measuring thermal properties of the flowing medium, the system uses sound wave propagation characteristics (which are affected by flow but not by sensor build-up) as a mediator to determine flow parameters.
2Reliability
If Coriolis meters are used to determine flow rate, then high reliability is achieved, but the purchase price is very high
Solution Approach 1:
The patent replaces the complex mechanical Coriolis measurement system with an acoustic measurement system. Instead of using oscillating tubes and Coriolis force measurement, the invention uses acoustic wave propagation through the flowing medium to determine flow rate, significantly reducing mechanical complexity and cost.
Solution Approach 2:
The patent uses acoustic wave propagation characteristics as a proxy or copy of the flow conditions. By measuring how acoustic waves travel through the medium (speed, attenuation), the system indirectly determines flow parameters without requiring direct mechanical interaction with the flow.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides a reliable, cost-effective means to determine flow properties by minimizing maintenance needs and avoiding the high costs associated with traditional methods, while maintaining accuracy and sensitivity to flow conditions.
Implementation Method 1
a heating source heats part of a medium and thereby increases its temperature and thereby reduces its density
Implementation Method 2
The time taken for the heated part of the medium to travel from the heating source to the optical measuring device is measured
Implementation Method 3
the mechanically oscillatable unit is excited to resonate, that the mechanical oscillations are received by the mechanically oscillatable unit and converted into an electrical reception signal
Data Source
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Figure 4
AI summary
The invention relates to a method and a device for determining at least one flow property of a gaseous or liquid medium that flows in a substantially laminar manner in a pipeline. The invention is characterized in that a change in the density of the medium is created at least temporarily by at least one modulating element in the vicinity thereof, said element being introduced into the pipeline, at least in the event that the medium flows with a speed that is different from zero; in that at least one unit which is spaced from the modulating element, which is introduced into the pipeline, and which can vibrate mechanically is stimulated to vibrate in a resonant manner; in that mechanical vibrations from the unit that can vibrate mechanically are received and converted into an electric received signal, said received signal being sensitive to the density that is changed by the modulating element; and in that the at least one flow property of the medium is determined from the reaction of the received signal of the unit that can vibrate mechanically to the change in the density.