Fan Speed Determination via Axial Pressure Wave Sensing
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Solution Overview
Problem
In open rotor configurations of turbine engines, direct physical measurement of propeller speed is challenging due to the lack of correlation between the rotational speed of the drive shaft and the propellers, which often rotate in opposite directions.
Innovation Solution
A method and apparatus that sense pressure waves generated by the blades of the fan to indirectly determine the speed of rotation, using a sensor positioned along the axis of rotation to emit signals corresponding to physical conditions changed by the rotation, processed by a processor to adjust engine operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct physical measurement of propeller speed is attempted in open rotor configurations, then measurement accuracy may be improved, but device complexity and difficulty of measurement increase due to lack of correlation between drive shaft speed and propeller speed
Solution Approach 1:
The patent replaces direct mechanical measurement systems with acoustic field-based measurement. Pressure sensors detect acoustic waves generated by propeller blade movement, converting mechanical motion into acoustic signals that can be analyzed to determine propeller speed, bypassing the need for direct mechanical coupling between measurement devices and the propeller shaft
Solution Approach 2:
The patent introduces acoustic waves as an intermediary medium between the propeller blades and the measurement system. Pressure sensors detect these acoustic waves, which serve as a mediator carrying information about blade position and speed without requiring direct physical contact or mechanical coupling with the rotating propeller
2Measurement precision
If pressure sensors are positioned close to the fan to improve signal strength, then measurement sensitivity is improved, but the risk of interference with fan operation and safety hazards increase
Solution Approach 1:
The patent positions pressure sensors in the acoustic field dimension rather than in direct proximity to the rotating blades. By measuring acoustic pressure waves at a distance along the rotation axis, the system captures sufficient signal information without placing sensors in the hazardous mechanical rotation zone, thus resolving the conflict between signal strength and safety
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
Enables accurate assessment of propeller speed and other parameters like blade pitch and vibration, improving engine control and efficiency without requiring direct measurement of the drive shaft speed.
Implementation Method 1
sense pressure waves generated by the blades of the fan
Data Source
AI summary
A method for determining the speed of at least one rotating fan, such as a propeller, through sensing pressure waves generated by the blades of the fan. An apparatus operable to execute the method is also disclosed. The apparatus includes a fan having a hub portion and a plurality of blades extending radially outward from the hub portion. The apparatus also includes an engine operable to rotate the fan about an axis of rotation. The apparatus also includes a sensor spaced from the fan along the axis of rotation. The sensor is positioned to sense at least one physical condition that is external of the engine and is changed by rotation of the plurality of blades. The sensor is operable to emit a signal corresponding to at least one physical condition. The apparatus also includes a processor operably engaged with the engine and the sensor. The processor is operable to receive the signal from the sensor and change the operation of the engine in response to the signal to change a speed of the fan.