Rotor Disk Bore Cavity Layout for Hoop Stress and Thermal Gradients
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Solution Overview
Problem
Gas turbine rotor disks face challenges in withstanding hoop stresses and thermal gradients due to their design, which can lead to material deflection and increased stress under high-speed and heated conditions.
Innovation Solution
The design incorporates a thicker bore body with a radially extending web and a peripheral rim, featuring a bore cavity that extends continuously around the central bore, reducing material thickness and incorporating bleed passages to manage thermal gradients and mechanical stresses, while allowing for air ingress and egress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the bore body is made thicker to withstand hoop stresses, then the strength increases, but the weight increases
Solution Approach 1:
The bore body is segmented into a outer wall, inner wall, and web portion, with the web portion having reduced thickness. This segmentation allows the critical hoop stress-bearing regions (outer and inner walls) to maintain sufficient thickness while reducing material in the web region, thereby reducing overall weight while preserving necessary strength.
Solution Approach 2:
The rotor disk employs non-uniform thickness distribution, with the bore body walls maintaining greater thickness for strength while the web portion has reduced thickness for weight reduction. This local quality variation optimizes the balance between strength requirements and weight reduction.
2Power
If the rotor disk operates at high speeds, then the power output increases, but the centrifugal forces and hoop stresses increase
Solution Approach 1:
By segmenting the bore body into distinct regions (outer wall, inner wall, web), the design can better manage stress distribution. The thicker outer and inner walls provide stress-bearing capacity while the reduced web thickness reduces mass, allowing higher rotational speeds without excessive centrifugal forces.
Solution Approach 2:
The thickness parameter of the bore body is varied across different regions rather than being uniform. This parameter change allows optimization of stress distribution and reduction of centrifugal forces, enabling higher operating speeds.
3Weight of moving object
If the web thickness is reduced to minimize weight, then the weight decreases, but the structural integrity decreases
Solution Approach 1:
The bore body is divided into functional segments where the web portion can be thinner without compromising overall integrity, as the outer and inner walls maintain sufficient thickness to bear loads. This segmentation allows weight reduction in the web while preserving structural integrity through the wall structures.
Solution Approach 2:
The outer and inner walls of the bore body serve multiple functions: they provide structural integrity, bear hoop stresses, and support the reduced-thickness web portion. This multi-functionality allows the web to be thinner while maintaining overall structural integrity.
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 design enhances the rotor disk's hoop strength, reduces thermal gradients, and minimizes weight by optimizing material distribution, thereby improving fatigue resistance and operational efficiency.
Implementation Method 1
Temperature gradients along a radial direction of the rotor disks can also place additional thermal stresses on the rotor disks, particularly at the inner bore body
Implementation Method 2
The bore cavity may allow for ingress and egress of air to and from the bore cavity
Data Source
AI summary
A rotor disk for a gas turbine engine includes a disk body having a central bore extending therethrough. The disk body includes a bore body that extends around the central bore, a web that extends radially outward from the bore body having decreased thickness relative to the bore body and a peripheral rim that is located at an outer end of the web. The peripheral rim includes blade mounting structures for engaging complementary mounting structures of rotor blades. The bore body has a bore cavity that extends continuously through the bore body and about an entire periphery of the central bore. The bore cavity has a central axis that forms a circle about the central bore.