Integrally Bladed Rotor Blade Off Testing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current blade off testing methods for gas turbine engines lack consistency and accuracy in liberating rotor blades, posing challenges for regulatory certification due to varying techniques and potential safety risks associated with explosive materials.
Innovation Solution
An integrally bladed rotor configuration with a hub and rotor blades featuring strategically placed slots and internal cavities, where a heating element is used to selectively reduce the mechanical strength of the airfoil material, allowing for controlled blade liberation during testing, eliminating the need for explosive materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If explosive materials are used to liberate rotor blades, then blade off testing can be performed, but safety risks increase and consistency of results deteriorates
Solution Approach 1:
The patent replaces explosive mechanical/chemical systems with a thermal field system. Heating elements embedded in the rotor blades use electrical energy to generate heat, which thermally degrades the adhesive bonding the blade to the hub. This substitution eliminates explosive materials while providing controlled, predictable blade liberation through thermal rather than mechanical/explosive means.
Solution Approach 2:
The patent changes the physical state and properties of the adhesive bonding material through temperature parameter changes. By controlling the temperature rise in specific regions of the blade via heating elements, the adhesive undergoes thermal degradation, transforming from a bonded state to a liberated state. This parameter-based control ensures consistent and repeatable blade liberation results.
2Object-affected harmful factors
If thermal degradation of adhesive is used to liberate rotor blades, then explosive materials are eliminated, but manufacturing complexity increases due to required slots and heating elements
Solution Approach 1:
The patent segments the rotor blade structure by incorporating multiple slots and internal cavities at specific locations. These segmented features create discrete heating zones that can be independently controlled, allowing precise control over where and when blade liberation occurs. The segmentation enables targeted thermal degradation of adhesive bonds without affecting the entire blade structure.
Solution Approach 2:
The patent embeds heating elements within internal cavities and slots that are integrated into the blade structure during manufacturing. The heating elements are nested within the blade's geometric features, creating a compact configuration where the thermal activation system is contained within the blade's own structure rather than adding external complex components.
3Reliability
If heating elements are embedded in rotor blades, then controlled blade liberation is achieved, but manufacturing precision requirements increase
Solution Approach 1:
The patent incorporates heating elements and thermal degradation features during the initial blade manufacturing process rather than as post-assembly additions. The slots, cavities, and heating element mounting structures are formed as part of the blade's tooling or machining process, ensuring precise and repeatable positioning. This preliminary integration eliminates the need for complex post-manufacturing alignment operations.
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 provides consistent and accurate blade off testing results, ensuring safety and reliability by predictably liberating the test blade, reducing the uncertainty associated with explosive methods and enhancing the testing process's predictability and safety.
Implementation Method 1
The at least one heating element is configured to selectively produce an amount of thermal energy sufficient to heat the airfoil material proximate the internal cavity from a first temperature to a second temperature
Implementation Method 2
at the second temperature the one or more mechanical strength properties of the airfoil material proximate the internal cavity are decreased
Data Source
AI summary
An integrally bladed rotor (IBR) for a gas turbine engine is provided. The IBR includes a hub, rotor blades that include a test blade, and at least one heating element. Each rotor blade has an airfoil with leading and trailing edges, suction side and pressure side surfaces, and a base end. The airfoil of the test blade includes at least one slot defining a void in the airfoil. The slot extends a lengthwise distance into the airfoil along a direction generally between the leading and trailing edges of the airfoil and terminates at a slot end surface. The airfoil includes at least one internal cavity extending lengthwise from the slot end surface. The heating element is disposed in the internal cavity and selectively produces thermal energy sufficient to heat the airfoil material proximate the internal cavity to a temperature at which the airfoil mechanical strength properties are decreased.