Aerodynamic Probe Clearance Geometry for Impurity and Icing Control
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Solution Overview
Problem
Existing aerodynamic measurement probes face challenges with impurity ingress, particularly from water droplets, ice particles, and solid particles, leading to jamming and icing issues, which affect measurement accuracy and response time, and conventional solutions are costly or vulnerable to environmental extremes.
Innovation Solution
Aerodynamic measurement probes with a designed functional clearance featuring an inner and outer annular groove and annular tab to create vortices that guide impurities away from the rotation mechanism, incorporating a drain hole configuration to discharge impurities effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large functional clearance is provided between the mounting plate and the rotating part to prevent jamming by particles, then the rotating part can pivot freely, but intense heat exchanges with the air at the base of the vane occur, making the probe vulnerable to icing
Solution Approach 1:
The gap is segmented into multiple functional zones: an outer annular groove for particle storage, an inner annular groove for vortex generation, and a functional clearance for rotation. This segmentation allows each zone to serve its specific purpose independently, preventing jamming while controlling heat exchange.
Solution Approach 2:
The annular grooves act as intermediary structures between the external environment and the rotating shaft. They intercept particles and manage airflow, preventing direct contact between particles and the shaft while regulating thermal exchange to reduce icing vulnerability.
2Reliability
If the functional clearance is made large to store particles and prevent jamming, then the rotating mechanism remains free-moving, but the probe becomes more susceptible to water ingress and electronic unit contamination
Solution Approach 1:
Different regions of the gap have different qualities: the outer annular groove has a rectangular profile optimized for particle storage, while the inner annular groove has a rounded profile optimized for vortex generation and water flow management. This local differentiation allows the system to handle both particles and water effectively.
Solution Approach 2:
The inner annular groove features a rounded profile that promotes vortex formation and smooth water flow, preventing water accumulation and directing water away from the electronic units. The curvature helps water drain more effectively compared to flat surfaces.
3Object-affected harmful factors
If sealed bearings are used to prevent impurity penetration, then the rotating mechanism is protected, but torque resists rotation and measurement accuracy/sensitivity is compromised
Solution Approach 1:
The sealing function is extracted from the bearing mechanism itself and transferred to the annular grooves and functional clearance design. The grooves and clearance work together to intercept and manage impurities, allowing the shaft to rotate freely without sealed bearings that would create friction torque.
4Object-affected harmful factors
If deformable protectors are used to seal the gap and prevent foreign body penetration, then the mechanism is protected from impurities, but measurement accuracy is reduced due to the sealing effect
Solution Approach 1:
The system uses the airflow itself to serve the protection function. The functional clearance and annular grooves are designed to utilize the air stream to carry away impurities and manage water flow, eliminating the need for deformable protectors that would interfere with measurement while still providing protection through the gap geometry.
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 effectively manages impurity ingress, preventing jamming and icing while maintaining measurement accuracy and response time, adhering to stringent environmental standards like DO-160, and is cost-effective.
Implementation Method 1
The gap comprises an inner annular groove (6) about the axis of rotation, made in the support and opening out away from the axis directly onto the end part of the annular tab, the profile of the inner groove being rounded... The design incorporates a gap between the support and the rotating shaft with an annular tab and grooves that promote the development of vortices to guide impurities towards drain holes
Data Source
AI summary
An aerodynamic measurement probe intended to measure a local angle of attack of an air stream flowing along the fuselage of an aircraft, includes a support and a shaft that is able to rotate about a longitudinal axis with respect to the support, the support and the shaft being configured to form between them a gap, passing around an annular tab at the end of the shaft in the support, making it possible to maintain a functional clearance to allow one end of the shaft to pivot freely in the support, and communicating with an impurity discharge circuit, the gap comprising an inner annular groove about the axis of rotation, made in the support, and opening out away from the axis directly onto the end part of the annular tab, the profile of the inner groove being rounded.