Turbine Disc Test Component with Bend Structure for Stress Simulation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for testing turbine discs in gas turbine engines fail to accurately replicate the combination of compressive axial and tensile hoop stresses caused by thermal gradients and rotation, leading to unrepresentative life expectancy predictions due to the large size and thermal lag of the discs.
Innovation Solution
A test component with a bend structure extending from a base, allowing for the application of a bending moment to simulate compressive axial stress, combined with rotation to apply circumferential hoop stress, effectively replicating the stresses experienced by turbine discs during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If simple spin testing of actual turbine disc is used, then testing simplicity is maintained, but stress accuracy deteriorates due to inability to replicate combined thermal and rotational stresses
Solution Approach 1:
The patent creates a simplified copy of the turbine disc (test component) that replicates the critical stress conditions without requiring the full-scale actual disc. The test component includes a disc portion with a bore that can be heated externally, and blade retention means to attach test blades, copying the essential geometry and stress pathways of the real component while enabling controlled thermal and rotational loading in a test environment.
Solution Approach 2:
The test component is segmented into distinct functional portions: a disc portion representing the turbine disc, blade retention means for mounting blades, and heating means for applying thermal gradients. This segmentation allows independent control and application of thermal, mechanical, and rotational loads to accurately simulate operating conditions while maintaining testing simplicity.
2Reliability
If large bore turbine disc is used, then operational realism is maintained, but thermal gradient effects worsen causing compressive axial stress that leads to erroneous test results
Solution Approach 1:
The patent controls and varies key parameters including the size and positioning of the bore, the application of external heating to create controlled thermal gradients, and the rotational speed. By adjusting these parameters, the test component replicates the thermal and mechanical conditions of actual turbine disc operation, including the compressive axial stress from thermal gradients, while maintaining operational realism.
Solution Approach 2:
The test component incorporates localized features such as a bore in the disc portion that can be selectively heated, creating localized thermal gradients that mimic real operating conditions. The blade retention means are positioned to replicate the local stress conditions at the disc-blade interface, ensuring accurate simulation of critical regions without requiring the entire large disc to be present.
3Measurement precision
If external heating is applied to simulate thermal gradients, then thermal stress simulation improves, but device complexity increases due to additional heating and bending mechanisms
Solution Approach 1:
The patent combines multiple loading functions into a single integrated test component: the disc portion serves as both the test specimen and the structure for applying thermal and mechanical loads. The heating means are integrated with the disc geometry, and the blade retention means are incorporated into the disc structure itself. This merging reduces the need for separate external fixtures and equipment, simplifying the overall testing setup while maintaining stress simulation accuracy.
Solution Approach 2:
The test component is designed to generate its own test conditions through self-service mechanisms. The disc portion with its bore structure can be heated to create thermal gradients, and when rotated, the centrifugal forces and thermal expansion automatically generate the combined compressive axial and tensile hoop stresses. The blade retention means use the rotation itself to apply loads to mounted blades, eliminating the need for separate actuation systems.
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
This method provides a more accurate simulation of in-service stresses, enabling better determination of turbine disc life expectancy and allowing for design refinements to prevent failure, by combining compressive axial and tensile hoop stresses in a test environment.
Implementation Method 1
applying a bending moment to said bend structure to generate a compressive axial load to simulate of external heating of the test component
Implementation Method 2
simultaneously rotating that test component to apply a circumferential hoop stress load to the test component
Implementation Method 3
the bore section takes time to heat up as a result of external heating within an operating engine. During this time the bore surface heats first whilst the centre of the bore remains relatively cool. This thermal gradient imparts a compressive axial stress on the bore
Data Source
AI summary
Rotatable discs combined with turbine blades in engines must be tested for critical life analysis. Thus, consideration must be made as to life expectancy for such components as a result of tensile circumferential hoops as generated by the weight of blades under rotation as well as compressive axial stress as a result of thermal gradients during initial warm up. Previous testing arrangements have considered tensile circumferential hoop stress but not compressive axial stress combinations such as “Von Mises” stress. By provision of bend structures 13, 223 a bending moment is created about a base 2, 22 formed in a test component 1, 21 such that a bending moment force 4, 24 creates a bending moment in the test component 1, 21. This bending moment results in a compressive axial stress reminiscent of that in a practical turbine engine disc as a result of initial thermal gradients. In such circumstances a more realistic testing of the component 1, 21 representative of a practical disc/blade combination is achieved.