Nested Tube Air Temperature Pressure Probe
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Solution Overview
Problem
Conventional Kiel probes are inadequate for accurately measuring total temperature and pressure in gas flows due to heat conduction issues and sensitivity to fluid flow angles, and they do not measure pressure effectively.
Innovation Solution
A temperature and pressure probe design featuring an elongate outer and inner tube arrangement with a vent pipe, where the temperature sensor is located in the inner cavity and the pressure sensor in the outer cavity, allowing for uniform flow over the temperature sensor and stagnation of gas for accurate pressure measurement, while the vent pipe vents fluid and supports the inner tube.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional Kiel probe with shroud is used to measure temperature, then the temperature sensor is protected and has high recovery factor, but heat conduction through the shroud wall causes measurement error and the probe cannot measure pressure
Solution Approach 1:
The probe is divided into separate functional sections: an outer tube for pressure measurement and an inner tube for temperature measurement. This segmentation allows each sensor to operate in its optimal environment without interference from heat conduction through a shared shroud structure.
Solution Approach 2:
The inner tube containing the temperature sensor is nested within the outer tube containing the pressure sensor. This nested configuration allows both measurements to be taken from a single probe insertion while maintaining thermal isolation between the sensors.
2Measurement precision
If a conventional Kiel probe is used, then temperature measurement is possible, but the measurement is sensitive to fluid flow angle and requires complex correction factors
Solution Approach 1:
The inner tube is designed with specific local features including apertures positioned to create a flow condition where fluid enters the inner cavity and impinges on the temperature sensor. This local flow configuration reduces sensitivity to the overall probe orientation angle compared to conventional Kiel probes.
3Measurement precision
If separate temperature and pressure probes are used, then accurate measurements can be obtained, but the instrumentation becomes complex and requires more probe insertions
Solution Approach 1:
The invention merges the functionality of separate temperature and pressure probes into a single combined probe. The outer tube provides pressure measurement capability while the nested inner tube provides temperature measurement capability, allowing both parameters to be measured simultaneously from one probe insertion point.
Solution Approach 2:
The combined probe structure serves multiple functions: the outer tube measures pressure while also providing structural support and flow conditioning for the inner tube, and the inner tube measures temperature while being thermally isolated from the outer tube. This multi-functionality reduces the overall number of probes needed in the system.
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 design provides accurate measurements of total temperature and pressure by minimizing heat conduction and flow angle sensitivity, and reduces the number of probes required for instrumentation, resulting in a more compact and efficient measurement system.
Implementation Method 1
a vent pipe coupled between the peripheral wall of the inner tube and the peripheral wall of the outer tube, the vent pipe having a first end open to the inner cavity and a second end open to vent outside the probe
Implementation Method 2
a temperature sensor located in the inner cavity
Implementation Method 3
a pressure sensor located in the outer cavity
Implementation Method 4
there is significant heat conduction from the temperature sensor 26 and its mounting stem through the shroud wall to the outside of the shroud 28
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A temperature and pressure probe (40) comprising an elongate outer tube (42) and elongate inner tube (56). Each tube having a peripheral wall (44, 58), a first open end (46, 60) and a second closed end (48, 62); the outer tube thereby defining an outer cavity (52) and the inner tube defining an inner cavity (66). The inner tube is located wholly within the outer cavity and is spaced from the outer peripheral wall (44) and second end (48). A temperature sensor (70) is located in the inner cavity. A pressure sensor (68) is located in the outer cavity. A vent pipe (76) is coupled between the inner peripheral wall and the outer peripheral wall, the vent pipe having a first end open to the inner cavity (66) and a second end open to vent outside the probe (40).