Piezoelectric Motor for Gas Turbine Rotor Bow Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas turbine engine rotor shaft bowing due to uneven cooling causes vibrations and potential damage, particularly in aircraft engines with tight clearances, and existing solutions like Engine Turning Motors face challenges with power availability and reliability, especially in remote airports and smaller aircraft.
Innovation Solution
A piezoelectric motor system is integrated to rotate the rotor shaft, using stators and rotor members connected to the shaft, which are actuated by electric fields to reduce or prevent thermal bowing, allowing for efficient rotation without the need for external power sources and minimizing weight and spatial requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If tighter cold build clearances are implemented to reduce air leakage and improve fuel consumption, then fuel efficiency is improved, but rotor shaft bowing causes more severe rub against the engine casing
Solution Approach 1:
The piezoelectric motor rotates the rotor shaft before engine start to preemptively counteract thermal bowing. By applying centrifugal forces and promoting uniform cooling during a preliminary rotation phase, the rotor shaft is positioned in a straightened state before the engine begins operation, preventing rub even with tight clearances
2Object-affected harmful factors
If conventional Engine Turning Motors are used to rotate the shaft for bow mitigation, then rotor shaft bowing is reduced, but power availability and reliability become problematic in remote airports and smaller aircraft
Solution Approach 1:
The piezoelectric motor is integrated directly into the rotor shaft assembly, making the bow mitigation system self-contained and self-serviceable. It eliminates dependence on external power sources by using its own integrated power supply, ensuring reliable operation regardless of airport location or APU availability
Solution Approach 2:
The conventional mechanical Engine Turning Motor system, which requires external electrical power and complex power transmission, is replaced with a piezoelectric motor system. This substitution uses piezoelectric materials that convert electrical energy directly to mechanical motion at the point of need, eliminating the need for external power infrastructure
3Ease of operation
If lithium-ion or nickel-cadmium batteries are used to power the Engine Turning Motor, then rotation for bow mitigation is achieved, but failure rates increase and flammability concerns arise in the engine environment
Solution Approach 1:
The power source parameters are fundamentally changed by transitioning from high-energy-density but hazardous batteries (lithium-ion, nickel-cadmium) to a piezoelectric system. This parameter change maintains the ability to generate sufficient torque for shaft rotation while eliminating flammability and reducing failure rates through the inherent stability of piezoelectric materials
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 piezoelectric motor effectively reduces rotor shaft bowing, preventing damage and vibrations, while simplifying ground logistics and reducing departure delays, with improved reliability and reduced energy demands compared to traditional systems.
Implementation Method 1
Aircraft engines with piezoelectric motors may be used to rotate the rotor shaft to reduce rotor bowing
Implementation Method 2
rotating the shaft (1) so that the shaft cools uniformly, returns to thermal equilibrium, and straightens, and/or (2) so that centrifugal forces straighten the bow
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A piezoelectric motor comprising one or more concentric stator rings arranged to transfer energy and provide torque to an engine rotor or to an engine transmission. Such a piezo-electric motor improves spatial integration of an engine turning motor in a gas turbine engine.