Preloaded Spring Damping for Gas Turbine Airfoil Flutter
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Gas turbine engine airfoils experience flutter and fatigue due to centrifugal, aerodynamic, and vibratory stresses, which current damping methods, such as elastomeric materials, fail to effectively resist, leading to potential damage and failure.
Innovation Solution
An airfoil design incorporating a preloaded spring within a pocket filled with an elastomeric material, which exerts force to resist flutter and dampen vibratory responses, and is configured to change the airfoil's inherent frequency outside the range of resonant frequencies, thereby preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If elastomeric material is used to fill airfoil pockets for damping, then mass is reduced and fuel performance improves, but the material fails to resist side-to-side, tip, and torsional flutter
Solution Approach 1:
The patent combines elastomeric material with a preloaded spring to create a composite damping system. The elastomeric material provides mass reduction and basic damping, while the preloaded spring component adds resistance to side-to-side, tip, and torsional flutter. This composite approach resolves the contradiction by maintaining the fuel performance benefits of reduced mass while adding the flutter resistance capability through the spring element.
2Speed
If airfoils are made hollow with pockets to reduce mass, then rotor speed increases and fuel performance improves, but the airfoils become more susceptible to flutter and vibratory stress
Solution Approach 1:
The preloaded spring in the damping device is pre-configured with a specific load before installation in the airfoil pocket. This preliminary action of preloading the spring ensures that it is already positioned to counteract flutter and vibratory stresses before the airfoil experiences operational loads. The preloaded state allows the spring to immediately resist side-to-side, tip, and torsional movements, protecting the hollow airfoil structure from flutter while maintaining the mass reduction benefits.
3Power
If airfoils are cantilevered from the rotor to enable rotation, then power generation is achieved, but the airfoils experience bending and flexing that lead to fatigue and failure
Solution Approach 1:
The damping device with the preloaded spring acts as an intermediary element between the hollow airfoil structure and the external vibratory loads. The spring absorbs and counteracts the bending and flexing forces generated during rotation, reducing the stress transmitted to the airfoil material. This intermediary damping mechanism protects the cantilevered airfoil from fatigue and failure while allowing it to continue generating power through rotation.
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 resists side-to-side, tip, and torsional movements, reducing the risk of fatigue and extending the life of gas turbine engine components, improving safety and reducing maintenance costs.
Implementation Method 1
a preloaded spring disposed within the filler. The preloaded spring may exert a force within the pocket for resisting flutter of the airfoil and for damping vibratory response of the airfoil
Implementation Method 2
for damping vibratory response of the airfoil
Implementation Method 3
the filler may dampen a vibratory response of the airfoil, prevent decompression of the preloaded spring
Implementation Method 4
the preloaded spring and the filler may be configured to change an inherent frequency of the airfoil to a predetermined frequency outside a range of resonant frequencies of the airfoil
Data Source
AI summary
An airfoil for a gas turbine engine and method of manufacture of the airfoil are disclosed. The airfoil may comprise a first side extending axially from a leading edge to a trailing edge and extending radially from a base to a tip, a second side opposite to the first side, a pocket disposed in the first side, a filler disposed in the pocket, and a preloaded spring disposed within the filler.