Rotating Load Cell for Propeller Thrust Measurement
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Solution Overview
Problem
Measuring thrust in propeller-driven aircraft engines is challenging due to non-thrust contributors, making estimates less accurate than actual measurements.
Innovation Solution
An aircraft powerplant configuration that includes a gas turbine engine with a load cell coupled to the shaft, allowing for direct measurement of propeller thrust through rotary motion conversion and strain gauge measurements, eliminating non-thrust contributors by averaging signals from multiple strain gauges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thrust is estimated using conventional methods, then the measurement process is simple, but the measurement precision is low due to non-thrust contributors
Solution Approach 1:
The measurement system segments the thrust measurement by using multiple strain gauges positioned at different locations on the propeller hub. Each strain gauge measures local strain, and through signal processing (averaging), the system separates true thrust from non-thrust contributors like 1P moments and propeller weight, thereby improving measurement precision without requiring a completely complex new system
Solution Approach 2:
The patent introduces strain gauges as intermediary sensing elements between the propeller thrust and the measurement system. These strain gauges convert mechanical strain into electrical signals that can be processed to extract accurate thrust information, serving as a mediator that enables precise measurement while managing system complexity
2Measurement precision
If a load cell is coupled to the rotating shaft to measure thrust, then measurement precision improves, but the device complexity increases due to rotary motion requirements
Solution Approach 1:
The measurement system is designed to dynamically rotate with the propeller shaft, with strain gauges and load cell mounted on rotating components. The system incorporates rotary joints and sliding contacts that enable electrical connections to maintain signal transmission during rotation, allowing precise thrust measurement while accommodating the dynamic rotating environment
Solution Approach 2:
Rotary joints and sliding contacts serve as intermediary elements that bridge the stationary measurement system and the rotating propeller shaft. These intermediaries transmit mechanical rotation and electrical signals between stationary and rotating components, enabling the load cell to measure thrust accurately while rotating with the shaft without creating excessive system complexity
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
Provides accurate and direct measurement of propeller thrust, improving measurement precision by accounting for non-thrust contributors like 1P moments and propeller weight.
Implementation Method 1
a load cell coupled to an end of the shaft and positioned to rotate with the shaft, the load cell configured for generating a measurement indicative of propeller thrust
Data Source
AI summary
An aircraft powerplant and a method for measuring thrust are described herein. A gas turbine engine has a turbine section for extracting energy from combustion gases and has a shaft mounted to the turbine section for converting the energy into rotary motion. A load cell is coupled to an end of the shaft and positioned to rotate with the shaft. The load cell is configured for generating a measurement indicative of propeller thrust. A propeller is coupled to the load cell and is configured for converting the rotary motion from the shaft and the load cell into the propeller thrust. The propeller thrust can be measured from the load cell as the propeller rotates.