High Angle of Attack Sensor Airfoil Design
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing total air temperature sensors face accuracy issues at high angles of attack due to flow separation, leading to recovery errors and convective film variations, limiting their effectiveness beyond a certain angle, such as +/- 15 degrees.
Innovation Solution
A sensing assembly with a symmetrical airfoil extension member and 'V' channel with rounded tips directs airflow to maintain attachment until ±50°, using pressure differentials to separate particles and channel air into an outer sheath around the sensing element, reducing velocity and promoting a uniform convective film for accurate temperature measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the angle of attack is increased beyond a certain angle, then the sensor can measure a wider range of flow conditions, but flow separation occurs on the airfoil leading to extreme recovery error and convective film variation
Solution Approach 1:
The patent uses a symmetrical airfoil cross-section (contrary to the asymmetry principle name, the actual application is symmetry) to ensure equal performance at positive and negative angles of attack, allowing the sensor to maintain accurate measurements at high angles up to ±30 degrees without flow separation-induced errors
Solution Approach 2:
The airfoil employs a curved, streamlined cross-sectional shape with specific camber and thickness distribution to delay flow separation and maintain attached flow at high angles of attack, enabling accurate temperature measurement across an extended angle range while preventing the flow separation that causes recovery errors
2Reliability
If the angle of attack increases beyond +/- 15 degrees, then more extreme flow conditions can be measured, but flow separation results in extreme recovery error
Solution Approach 1:
The symmetrical airfoil cross-section ensures identical aerodynamic characteristics at +α and -α angles of attack, maintaining reliable temperature measurements at high angles by preventing asymmetric flow separation that would cause recovery errors and convective film variations
Solution Approach 2:
The airfoil geometry parameters (camber, thickness distribution, leading edge radius) are specifically optimized to maintain attached flow at high angles of attack, changing the flow regime from separated to attached flow and eliminating recovery errors while ensuring reliable sensor performance
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
The solution enables accurate temperature sensing over a wider angle range (±30°) with reduced recovery errors and transient responses, effectively managing flow separation and particle impact, while maintaining reliability in harsh environments.
Implementation Method 1
using pressure differentials to separate particles and channel air into an outer sheath around the sensing element
Implementation Method 2
reducing velocity and promoting a uniform convective film for accurate temperature measurement
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method (400) and an assembly (100) for sensing a process parameter are provided. The sensing assembly includes a base (102) and a sensor assembly (104). The sensor assembly includes a sensing element (106), a first flow channel(108), and a second flow channel (110). The first flow channel includes a converging segment (328), a straightening segment (330), and a turning segment (332) wherein the turning segment includes a turn radius (334) configured to separate particles from a flow (336) entering the turning segment and the second flow channel is configured to generate a low pressure area (344) downstream of the sensing element. The sensing assembly also includes an extension member (112) extending between the base and the sensor assembly.