Vortex Flow Meter Throttle for Vapor Pressure Control
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Solution Overview
Problem
Existing flow measuring devices based on the vortex meter principle face issues with pressure loss leading to vapor pressure undershoot, which can prevent reliable flow measurement, especially in liquid media.
Innovation Solution
A flow measuring device with a measuring tube featuring a bluff body and a vortex detector, including a throttle that axially narrows the flow cross section, creating a significant pressure drop while maintaining static pressure above vapor pressure levels, preventing outgassing and cavitation through a radial diameter transition and strategically placed pressure sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a bluff body is used to generate vortex street for flow measurement, then flow velocity can be determined through vortex frequency, but pressure loss occurs causing vapor pressure to fall below the limit
Solution Approach 1:
The patent introduces a preliminary action by placing a throttle element upstream of the bluff body to pre-regulate the flow. This preliminary flow restriction ensures that the pressure drop across the bluff body does not cause the vapor pressure to fall below the limit, while still allowing sufficient flow to reach the vortex detector for accurate measurement.
Solution Approach 2:
The throttle element acts as an intermediary component between the flow source and the bluff body. It mediates the pressure loss by creating a controlled restriction that prevents vapor pressure undershoot while maintaining the vortex generation necessary for flow measurement.
2Object-affected harmful factors
If the flow cross-section is narrowed to increase pressure drop, then vapor pressure undershoot is prevented, but flow velocity decreases
Solution Approach 1:
The patent applies local quality by creating a localized flow restriction at the throttle element rather than uniformly narrowing the entire flow path. This localized restriction prevents vapor pressure undershoot at the critical measurement zone while maintaining higher flow velocity in the overall system by minimizing the impact on the vortex generation region.
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
Ensures reliable flow measurement by maintaining static pressure above vapor pressure, preventing damage and ensuring accurate readings even when vapor pressure would otherwise be undershot, thereby overcoming the limitations of pressure loss in vortex meter devices.
Implementation Method 1
a bluff body arranged in the measuring tube, the bluff body serving to cause a Karman vortex street with a flow-dependent vortex frequency when a fluid flows through the measuring tube
Implementation Method 2
the throttle has a flow resistance which is not less than 50%, for example not less than 75%, further for example less than 90%, in particular not less than 95% of the flow resistance of the flow measuring device between the inlet-side end face and the vortex detector
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to: a measuring tube (10) for guiding a fluid for a flow meter device (1) according to the vortex measuring principle, wherein the measuring tube has an inflow-side opening in an inflow-side end face and an outflow-side opening in an outflow-side end face, between which the measuring tube extends in the axial direction; a bluff body (15) which is arranged in the measuring tube (10), wherein the bluff body functions to bring about a Kármán vortex street with a flow-rate-dependent vortex frequency when a fluid flows through the measuring tube; and at least one vortex detector (16) for detecting vortexes of the vortex street and for providing vortex-dependent signals; characterised in that the measuring tube (10) has a control valve (14), between the vortex detector (16) and the outflow-side end face and axially spaced apart from the vortex detector, which annularly constricts the flow cross-section of the measuring tube (10).