Airflow Conductivity Index for Crack Detection in Sealed Cavities
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Solution Overview
Problem
Existing condition monitoring systems for structures do not effectively utilize an unregulated vacuum source connected to a flow regulator and fail to provide measurements related to volumetric airflow or calculate a conductive index for air flow, limiting their ability to detect impending faults.
Innovation Solution
An apparatus comprising a first pressure transducer for measuring pressure from an unregulated pressure source, a second pressure transducer for measuring pressure on the cavity side of the fluid flow restrictor, a continuity valve for venting the cavity to atmospheric pressure, a bypass valve for direct fluid communication, and an ambient pressure sensor for calculating a conductivity index, which measures air flow conductivity through a sealed cavity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an unregulated vacuum source is connected to a flow regulator through a high fluid flow impedance, then the system can monitor for impending faults, but the system fails to provide accurate measurements of volumetric airflow and conductive index
Solution Approach 1:
A regulated vacuum source is introduced as an intermediary between the unregulated vacuum source and the flow regulator. This intermediary component stabilizes the pressure input to the flow regulator, enabling accurate volumetric airflow measurements while maintaining the fault detection capability of the original system.
Solution Approach 2:
The system transitions from using an unregulated vacuum source to a regulated vacuum source, changing the pressure parameter from variable to controlled. This parameter change enables the flow regulator to operate in its optimal range for measuring volumetric airflow and calculating conductive index accurately.
2Reliability
If a flow restrictor is used in the monitoring system, then the system can detect cracks and faults, but the system cannot distinguish between perfect sealing and actual crack conditions
Solution Approach 1:
The system incorporates feedback through the measurement of volumetric airflow and calculation of conductive index. By continuously monitoring these parameters and comparing them against threshold values, the system can distinguish between perfect sealing conditions and actual crack conditions, providing precise feedback on the sealing status.
Solution Approach 2:
The system replaces simple binary detection (sealed/not sealed) with a quantitative measurement system that uses volumetric airflow measurement and conductive index calculation. This substitution transforms the mechanical sealing detection into a precise quantitative assessment, allowing differentiation between various degrees of sealing integrity.
3Measurement precision
If repeated measurements are taken to track crack development, then fault detection sensitivity improves, but the system complexity and measurement requirements increase
Solution Approach 1:
The monitoring system is designed with multi-functionality to handle repeated measurements efficiently. The same apparatus performs initial assessment, continuous monitoring, and trend analysis of crack development using the volumetric airflow and conductive index measurements, eliminating the need for separate specialized equipment for different measurement stages.
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
Enables accurate detection of air leaks and crack formation in structures by calculating a conductivity index, providing a non-zero reading when the cavity is not perfectly sealed, and allowing for repeated measurements to track changes in crack size or development over time, enhancing fault detection sensitivity and accuracy.
Implementation Method 1
a first pressure transducer providing a measure of pressure P1 of the unregulated pressure source; and, a second pressure transducer providing a measure of pressure P2 on a side of the cavity connected with the fluid flow restrictor
Implementation Method 2
an apparatus (10) for monitoring the condition of a component or structure (12) by measuring the conductivity to air flow of a sealed cavity (14) formed on the surface of the structure (12). An unregulated pressure source (16) is coupled to the cavity (14) via a fluid flow restriction (17)
Implementation Method 3
the apparatus may further comprise a continuity valve coupled to an end of the cavity opposite the fluid flow restrictor, the continuity valve having a ON state in which the valve is open and vents the cavity to atmospheric pressure
Data Source
Figure 1
AI summary
An apparatus (10) monitors the condition of a component (12) by measuring the conductivity to air flow of a sealed cavity (14) formed on the surface of the component (12). The apparatus (10) comprises an unregulated pressure source (16) that is coupled to the cavity (14) via a fluid flow restriction (17). A measurement system (19) provides a measurement of, or related to, the volumetric air flow through the restriction (17), and calculates a conductivity index CI to air flow of the cavity in accordance with the equation CI = flow/pressure difference. In this equation "flow" is the volumetric flow of air through the flow restriction and "pressure difference" is the difference in pressure across the cavity with reference to atmospheric or ambient pressure. In the event that a crack traverses the cavity and provides a flow path to the atmosphere, the conductivity index CI will be a non-zero value. The higher the conductivity index the larger the crack.