Thermal Imaging Temperature Measurement Using Coated Surfaces
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Solution Overview
Problem
Traditional temperature measurement methods, such as pyrometers and thermocouples, fail to effectively identify localized high-temperature areas, known as hot spots, which can weaken metallic parts during heating processes, especially in non-uniform geometries like those in gas turbine engines.
Innovation Solution
A method involving the application of a non-reactive, thermally conductive coating with known infrared emissivity to a part, followed by heating and using thermal imaging to measure temperature distribution, allowing for the identification and control of hot spots by connecting localized temperature measuring devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional temperature measurement methods (pyrometers and thermocouples) are used, then the measurement process is simple, but the ability to identify localized hot spots is insufficient
Solution Approach 1:
A coating layer is applied to the part surface as an intermediary medium. This coating has known infrared emissivity properties that enable accurate thermal imaging measurement. The coating acts as a mediator between the hot spot detection requirement and the thermal imaging device, allowing precise measurement of localized high-temperature areas without direct contact or complex measurement systems.
Solution Approach 2:
The coating changes the infrared radiation characteristics of the part surface by providing a uniform, known emissivity value. This is analogous to color changes in visible light, where the coating's infrared 'color' or emissivity property is standardized to enable accurate temperature measurement through thermal imaging, transforming the measurement capability from insufficient to precise.
2Measurement precision
If thermal imaging with coating is used, then hot spot detection accuracy is improved, but the process requires additional coating application steps
Solution Approach 1:
The coating is applied to the part surface before the heating process begins. This preliminary action prepares the surface with known emissivity characteristics, enabling accurate thermal imaging measurement during subsequent heating operations. By performing the coating application in advance, the measurement precision is ensured without complicating the actual heating and measurement process.
3Ease of manufacture
If no coating is applied, then the process is simpler, but infrared measurement accuracy is reduced due to unknown emissivity
Solution Approach 1:
The emissivity parameter of the part surface is changed and standardized by applying a coating with known emissivity characteristics. This parameter change transforms the measurement condition from uncertain (unknown emissivity of raw part surface) to controlled and accurate (known emissivity of coating), enabling precise infrared temperature measurement while maintaining process feasibility.
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 and control of hot spots, preventing overheating and maintaining mechanical integrity of the part by ensuring uniform heating and reducing thermal stresses.
Implementation Method 1
the coating conducting thermal energy from the underlying part
Implementation Method 2
measuring infrared light emitted from the heated coating
Data Source
AI summary
A method of measuring temperature of a part heated during a heating process includes applying a non-reactive coating at a first temperature; heating the part, and thereby the coating thereon, to a second temperature greater than the first temperature; and measuring a temperature distribution of the part by measuring infrared light emitted from the heated coating using a thermal imaging device calibrated to the known emissivity of the coating. The coating is at least partially opaque and having a known emissivity of infrared light and conducts thermal energy from the underlying part.