Cavity-Based Fluid Speed Sensor Resolving Pitot Tube Icing
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Solution Overview
Problem
Pitot tubes used for measuring fluid speed are often rendered inoperative due to icing and other obstructions, leading to incidents such as those experienced by Airbus and Boeing, where ice accumulation at high altitudes and specific atmospheric conditions cause sensor failure.
Innovation Solution
A device with a self-sustained oscillation mechanism within a cavity, utilizing sensors to measure aerodynamic or hydrodynamic instability, which calculates fluid speed through frequency analysis and temperature regulation, ensuring operational reliability across varying conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a Pitot tube is used to measure fluid speed, then the measurement principle is simple and well-established, but the sensor becomes inoperative due to icing and obstructions
Solution Approach 1:
The patent replaces the mechanical Pitot tube pressure measurement system with an acoustic measurement system using microphones to detect self-sustained oscillations. This substitution eliminates the physical opening that vulnerable to icing, as the acoustic sensors can be positioned behind protective structures while still detecting the aerodynamic oscillations generated by the cavity
Solution Approach 2:
The patent introduces an aerodynamic cavity as an intermediary element that converts fluid flow information into self-sustained oscillations. These oscillations serve as a mediator that carries speed information to the sensors without requiring direct sensor exposure to the fluid stream, thereby protecting against icing while maintaining measurement capability
2Reliability
If the downstream wall height is increased to enhance oscillation generation, then the aerodynamic instability is improved, but the device complexity increases
Solution Approach 1:
The patent optimizes the cavity geometry parameters, specifically setting the downstream wall height between 0.02L and 0.05L (where L is cavity length) and the inclination angle between 10° and 45°. These parameter changes ensure reliable self-sustained oscillation generation while controlling structural complexity through defined ranges
3Measurement precision
If multiple sensors are installed in the cavity walls to measure instabilities, then the measurement accuracy is improved, but the device complexity and cost increase
Solution Approach 1:
The patent uses a single microphone positioned at a specific location within the cavity to detect the dominant self-sustained oscillation frequency. This partial action approach achieves sufficient measurement accuracy by focusing on the primary oscillation mode rather than using multiple sensors to capture all possible flow characteristics
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 device effectively estimates fluid speed by analyzing self-sustained oscillations and spectral density, providing accurate and reliable measurements even in conditions that would obstruct traditional Pitot tubes, enhancing safety and performance.
Implementation Method 1
a cavity (1) open to the outside by a single opening is touched by the relative movement of said fluid with respect to said main body (40) along an axis X, which generates within said cavity (1) a phenomenon of self-sustained oscillation depending on the speed of movement of said fluid
Data Source
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AI summary
The invention relates to a device for measuring the traveling speed of a fluid relative to an object. Said device is characterized in that it includes at least one sensor (2), placed in a suitable area of the object. Said at least one sensor (2) is capable of determining and using, by interacting with at least one computer (3), a local aerodynamic or hydrodynamic instability resulting from the relative movement of said fluid in relation to an element (1) of said object and dependent on the traveling speed of the fluid. The device is characterized in that said element (1) is an obstacle or hollow cavity having a single opening arranged in a body (40) and open toward the outside of said body. Said body is located on the object for which the relative speed of the fluid is sought such that the fluid grazes said cavity (1). The device is also characterized in that said at least one aerodynamic/hydrodynamic instability sensor (2) uses the process of self-oscillating said fluid within the cavity (1) to determine the relative movement speed thereof.