Airfoil Differential Pressure Flow Meter for HVAC Ducts
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Solution Overview
Problem
There is a need for a fluid flow rate measuring device that uses an airfoil and differential pressure to calculate fluid flow rates in conduits, such as HVAC ducts, as existing technologies do not effectively address this requirement.
Innovation Solution
A fluid flow rate measuring device comprising an airfoil with specific geometrical features, a differential pressure sensor, and a programmable electronic controller, which calculates fluid flow rate by measuring differential pressure and using a K factor based on conduit cross-sectional area, displayed on a touch screen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing flow measuring devices are used in HVAC ducts, then fluid flow rates can be measured, but the devices are complex, difficult to install, and do not effectively utilize airfoil-based differential pressure measurement
Solution Approach 1:
The patent extracts the core measurement function from complex existing flow meters by using only an airfoil section with pressure taps connected to a differential pressure sensor. This eliminates unnecessary components of traditional flow meters while retaining the essential measurement capability, directly resolving the contradiction between measurement reliability and device complexity
Solution Approach 2:
The patent replaces complex mechanical flow measurement mechanisms with a simplified system based on airfoil aerodynamics and differential pressure sensing. The airfoil's pressure distribution in subcritical flow conditions provides a direct relationship between differential pressure and flow rate, eliminating the need for complex mechanical components found in traditional flow meters
2Measurement precision
If traditional flow meters are installed in HVAC ducts, then flow measurement is possible, but installation is difficult and requires significant duct modification
Solution Approach 1:
The patent segments the measurement function into a minimal set of components: an airfoil section with pressure taps and connection ports. This segmentation allows the device to be installed as a simple insert in the duct rather than requiring replacement of entire duct sections or complex assembly, directly improving installation ease while maintaining measurement precision
Solution Approach 2:
The airfoil-based device serves multiple functions: it measures flow rate through differential pressure, can be installed in various duct configurations, and provides accurate measurement across different flow conditions. This universality allows a single simple design to replace multiple specialized components, improving both installation ease and measurement precision
3Measurement precision
If airfoil-based differential pressure measurement is implemented, then accurate flow rate calculation is achieved, but the device requires precise geometric features and pressure tap placement
Solution Approach 1:
The patent operates in a specific parameter regime (subcritical flow conditions) where the relationship between differential pressure and flow rate is well-defined and stable. By constraining operation to this parameter range, the system achieves high measurement precision without requiring extremely tight manufacturing tolerances, as the aerodynamic behavior is predictable and repeatable in this regime
Solution Approach 2:
The patent applies local quality by creating specific geometric features (pressure taps, rounded leading edge) at critical locations on the airfoil. These localized features are precisely formed where needed while other portions of the airfoil can be manufactured with standard tolerances, balancing manufacturing precision requirements with measurement accuracy needs
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
Accurately measures fluid flow rates in HVAC ducts by converting differential pressure measurements into volumetric flow rates, providing reliable and precise data for fluid flow monitoring.
Implementation Method 1
uses an airfoil and differential pressure to calculate a fluid flow rate in a conduit
Implementation Method 2
The airfoil includes a leading edge, a substantially flat surface, a shaped surface, a chord and a trailing edge. The substantially flat surface defines a high pressure side of the airfoil. The shaped surface defines a low pressure side of the airfoil.
Data Source
AI summary
An fluid flow rate measuring device preferably includes an airfoil, a differential pressure sensor and a programmable electronic controller. The airfoil includes a leading edge, a first pressure chamber, a second pressure chamber, and a trailing edge. At least one first hole is formed through the first pressure chamber. At least one second hole is formed through the second pressure chamber adjacent the trailing edge. The at least one first hole communicates with the first pressure chamber. The at least one second hole communicates with the second pressure chamber. The first and second pressure chambers are connected to first and second input ports of the differential pressure sensor. The differential pressure sensor outputs a voltage to the programmable electronic controller. The programmable electronic controller takes a square root of the differential pressure and multiplies it by a K factor to produce an fluid flow rate in CFM.