Total Air Temperature Sensor Strut Turbulence Inducing Surface
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Solution Overview
Problem
Conventional total air temperature sensors in aerospace applications face challenges with acoustic noise emissions due to aeroelastic vortex-induced vibrations, which can lead to structural failure and inaccurate temperature measurements.
Innovation Solution
The design incorporates a turbulence inducing surface on the strut of the total air temperature sensor, transitioning the fluid boundary layer from laminar to turbulent flow, reducing acoustic noise emissions and Kármán vortex interaction through features like serrated surfaces, linear channels, and dimples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional smooth strut surface is used, then manufacturing is simple, but acoustic noise emission increases due to laminar flow separation and Kármán vortex streets
Solution Approach 1:
The strut surface is modified with localized turbulence inducing features (such as turbulators, dimples, or serrations) at specific locations rather than changing the entire surface. This creates local turbulence zones that trip the boundary layer from laminar to turbulent flow, preventing large-scale flow separation and reducing acoustic noise while maintaining manufacturing simplicity for the overall structure.
Solution Approach 2:
The surface characteristics of the strut are changed by introducing turbulence inducing features that alter the boundary layer parameters. These features modify the flow regime by triggering early transition from laminar to turbulent flow, changing the separation behavior and reducing vortex-induced vibrations and acoustic emissions.
2Loss of energy
If laminar flow is maintained over the strut, then drag is reduced, but flow separation becomes unstable causing acoustic noise and vibration
Solution Approach 1:
Turbulence inducing features are placed on the strut surface at strategic locations upstream of the separation zone. These features preliminarily trip the boundary layer to turbulent flow before natural separation occurs, ensuring stable attachment and preventing unstable laminar separation and associated acoustic noise and vibrations.
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 effectively reduces acoustic noise emissions and Kármán vortex interactions, enhancing the performance and reliability of total air temperature sensors by improving flow separation and reducing the risk of structural failure.
Implementation Method 1
The turbulence inducing surface is configured to trip a fluid boundary layer passing over the strut to transition from laminar to turbulent
Implementation Method 2
moving flow separation toward the trailing edge
Implementation Method 3
reduce acoustic noise emission from the total air temperature sensor
Implementation Method 4
Kármán vortices develop cyclic forces that are mainly perpendicular to the airflow and cause aeroelastic vortex induced vibration
Implementation Method 5
Aeroelastic vortex induced vibration sound generation can effect TAT sensors or any airfoil
Data Source
AI summary
A total air temperature sensor includes a probe head, a strut, and a turbulence inducing surface. The probe head has an airflow inlet and an airflow outlet. The strut defines a leading edge and an opposed trailing edge extending along a longitudinal axis, and connects between the probe head and an opposed probe mount. The turbulence inducing surface is defined in the strut aft the leading edge. The turbulence inducing surface is configured to trip a fluid boundary layer passing over the strut to transition from laminar to turbulent for moving flow separation toward the trailing edge to reduce acoustic noise emission from the total air temperature sensor.