Pitot Tube Flowmeter Multi-Point Pressure Measurement
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Solution Overview
Problem
Pitot tube type flowmeters experience errors in measured flow rate due to changes in flow velocity distribution caused by varying pipe shapes on the upstream side.
Innovation Solution
The pitot tube type flowmeter includes a pitot tube with total and static pressure holes, and a differential pressure sensor. The pitot tube has a main tube portion and multiple branch tube portions, all designed to reduce pressure loss and increase measurement points for total and static pressures, allowing for more accurate flow rate measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional pitot tube is used with a single measurement point, then the device complexity is low, but the measurement precision deteriorates when flow velocity distribution changes due to upstream pipe shapes
Solution Approach 1:
The pitot tube is divided into multiple measurement sections (first measurement section and second measurement section) with separate total pressure holes and static pressure holes in each section. This segmentation allows independent measurement at different locations, enabling the system to compensate for flow velocity distribution changes caused by upstream pipe shapes while maintaining manageable structural complexity through modular design
Solution Approach 2:
The invention transitions from a single-point measurement to a multi-point measurement approach by adding measurement sections in the longitudinal dimension. The first measurement section is positioned upstream of the second measurement section, creating a spatial distribution of measurement points that captures flow velocity variations across different locations in the flow passage
2Measurement precision
If multiple measurement sections are added to improve measurement precision, then the measurement precision improves, but the device complexity increases
Solution Approach 1:
Multiple measurement sections are integrated into a single unified pitot tube structure rather than using separate devices. The first and second measurement sections are combined in one tube with appropriate spacing, allowing simultaneous multi-point measurement while avoiding the complexity of coordinating multiple independent devices. The differential pressure sensor connects to both sections through a unified structure, simplifying the overall system
Solution Approach 2:
The pitot tube structure serves multiple functions simultaneously: it performs total pressure measurement, static pressure measurement, and flow rate calculation all within a single device. The multiple measurement sections enable the same structure to compensate for various flow distribution patterns, making the device adaptable to different upstream pipe configurations without requiring separate specialized components
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 configuration reduces errors in measured flow rate by averaging total and static pressure measurements across a two-dimensional plane, even when flow velocity distributions change, and minimizes pressure loss within the flow passage.
Implementation Method 1
a differential pressure sensor that is connected to the pitot tube and detects a differential pressure between the total pressure and the static pressure
Implementation Method 2
total pressure holes for detecting a total pressure of a fluid
Implementation Method 3
static pressure holes for detecting a static pressure of the fluid
Data Source
AI summary
The present invention makes a pitot tube type flowmeter less affected by the flow velocity distribution caused by the flow passage shape on the upstream side, and includes a pitot tube having total pressure holes for detecting a total pressure of a fluid and static pressure holes for detecting a static pressure of the fluid, and a differential pressure sensor that is connected to the pitot tube and detects a differential pressure between the total pressure and the static pressure. The pitot tube includes a main tube portion, and a plurality of branch tube portions, which branches off from the main tube portion and in which the total pressure holes and the static pressure holes are formed. Each of the main tube portion and the plurality of branch tube portions has a shape that reduces a pressure loss.