Integral Turbine Rotor Impingement Cooling Design
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Solution Overview
Problem
Current gas turbine engine cooling schemes fail to adequately cool the disk surface, particularly the 'throat' region, leading to high component metal operating temperatures and temperature gradients, especially during start-up and transient operational conditions, limiting the ability to operate at optimally high temperatures without risking melting or oxidation.
Innovation Solution
An integral turbine rotor design with a split-hub configuration and impingement cooling, where cooling air flows through internal cavities to impinge against the radial surface, providing convective and conductive cooling, and allowing for the use of disparate materials tailored to specific operating conditions for the forward and aft hub sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If turbine inlet temperatures and rotational speeds are increased to improve engine performance, then efficiency and thrust-to-weight ratio are improved, but thermal and mechanical demands on turbine components increase leading to alloy weakening and melting
Solution Approach 1:
The turbine rotor is divided into multiple sections (forward hub section and aft hub section) that are metallurgically coupled, allowing each section to be optimized for specific thermal and mechanical conditions. This segmentation enables disparate materials to be used in different regions to withstand varying temperature and stress levels.
Solution Approach 2:
Different materials are used in different regions of the turbine rotor based on local thermal and mechanical demands. The forward and aft hub sections can utilize materials with properties tailored to their specific operating conditions, with the blade ring and hub sections optimized for their respective environments.
2Temperature
If conventional cooling schemes are used, then some cooling is provided, but the disk surface particularly the throat region is not adequately cooled, resulting in high component metal operating temperatures and temperature gradients
Solution Approach 1:
The cooling approach transitions from conventional surface cooling to internal impingement cooling, where cooling air is directed through passages within the hub sections to impinge on the disk surface from the interior. This three-dimensional cooling approach directly targets the throat region and mid-disk rim areas that were previously difficult to cool.
Solution Approach 2:
Cooling air is channelled through internal passages in the hub sections to create impingement flows that directly cool the disk surface. The pneumatic system delivers cooling air through the forward and aft hub sections to the impingement cavities, enabling direct convective cooling of critical surface regions.
3Ease of manufacture
If a monolithic turbine rotor design is used, then manufacturing is simpler, but material optimization for specific operating conditions is limited
Solution Approach 1:
The turbine rotor is manufactured as separate sections (forward hub section, aft hub section, and blade ring) that are subsequently metallurgically coupled. This segmentation allows each component to be manufactured and optimized independently with materials best suited for their specific operating conditions, then assembled into the complete rotor.
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 mid-disk rim cooling, enabling the turbine to operate at higher temperatures with reduced thermal degradation, improved structural independence of blades, and optimized material usage for enhanced performance and efficiency.
Implementation Method 1
cooling air flows from the central opening via the cooling air passage into the internal hub cavity
Implementation Method 2
an impingement cooling air flow impinges against the interior surface of the impingement cavity to provide convective and conductive cooling
Implementation Method 3
an impingement cooling air flow impinges against the interior surface of the impingement cavity to provide convective and conductive cooling
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An integral turbine rotor (20, 120) includes a forward hub section (56, 156) and an aft hub section (60, 160). The forward hub section and the aft hub section are metallurgically coupled to one another along an annular interface (54, 157) that resides within a plane generally orthogonal to a rotational axis (26) of the axially-split turbine. The turbine further includes an airfoil blade ring metallurgically coupled to a radial outer surface of the coupled forward and aft hub sections and an impingement cavity (68b, 70b, 168b, 170b) formed within an interior portion of the coupled forward and aft hub sections. The impingement cavity includes an interior surface (75, 175) that is positioned proximate to the radial outer surface of the coupled forward and aft hub sections. Further, an impingement cooling air flow (88, 188) impinges against the interior surface of the impingement cavity to provide convective and conductive cooling to the radial outer surface of the coupled forward and aft hub sections.