Gas Turbine Blade Cooling Interface Plenum Design
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Solution Overview
Problem
Existing gas turbine blade cooling designs face challenges with non-uniform cooling fluid distribution, flow separation, and increased pressure losses due to mismatched interfaces between the rotor bore exit and blade inlet, limiting flexibility and preventing multi-pass designs.
Innovation Solution
An interface plenum is created between the blade root and rotor groove with a diffuser-shaped rotor bore exit, allowing for plenum bleeding and deceleration of the cooling fluid flow, enabling uniform distribution and flexible orientation of the rotor bore, and splitting the blade core into parallel cooling ducts with individual cross-section areas and mass flows for optimized cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a unique passage smoothly distributes the flow all over the cross section of the duct, then the flow distribution is improved, but the area/shape mismatch between rotor bore exit and blade inlet causes flow separation and increased pressure loss
Solution Approach 1:
An interface plenum is introduced as an intermediary chamber between the rotor bore exit and the blade inlet. This plenum acts as a mediator that receives the cooling fluid from the rotor bore and redistributes it uniformly across the blade inlet cross-section, eliminating the direct area/shape mismatch and preventing flow separation while minimizing pressure losses.
Solution Approach 2:
The cooling fluid flow path is segmented into distinct sections: the rotor bore, the interface plenum, and the blade inlet passages. This segmentation allows each component to be optimized independently - the rotor bore for its specific flow characteristics and the blade inlet for its cooling requirements - while the plenum ensures smooth transition between segments.
2Adaptability or versatility
If the rotor bore is positioned inclined with respect to the blade, then the rotor bore orientation flexibility is improved, but the flow separation area gets expanded and the situation worsens
Solution Approach 1:
The interface plenum serves as a flow-conditioning intermediary that decouples the rotor bore orientation from the blade inlet requirements. It receives cooling fluid from any rotor bore orientation and transforms it into uniform flow distribution across the blade inlet, preventing flow separation regardless of the rotor bore's angular position relative to the blade.
3Reliability
If a convoluted serpentine cooling passage is provided in the airfoil, then the cooling coverage is improved, but the bends give rise to pressure losses without heat transfer
Solution Approach 1:
The cooling system is segmented into multiple independent parallel passages within the blade core, each with its own dust holes for flow control. This segmentation allows cooling fluid to be distributed through multiple straight pathways rather than a single convoluted serpentine passage, reducing bends and associated pressure losses while maintaining comprehensive cooling coverage.
4Device complexity
If only one flow of cooling fluid is provided in the airfoil, then the structure is simplified, but it is difficult to adapt this flow to the various cooling requirements existing at different locations of the airfoil
Solution Approach 1:
The cooling fluid flow is divided into multiple independent parallel passages within the blade core, each capable of being controlled separately through adjustable dust holes. This segmentation enables the cooling requirements at different locations of the airfoil to be met by independently controlling the flow in each passage, while the overall structure remains relatively simple.
Solution Approach 2:
The dust holes in each cooling passage are made adjustable, allowing the mass flow in each passage to be dynamically controlled according to the specific cooling requirements at different locations. This dynamic adjustability enables the cooling system to adapt to varying thermal loads without changing the physical structure of the passages.
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 configuration reduces pressure losses, prevents flow separation, allows for flexible rotor bore orientation, and enables a multi-pass design with improved cooling effectiveness and control over local mass flows, enhancing the blade's cooling efficiency with minimal redesign.
Implementation Method 1
a diffuser-shaped rotor bore exit (24) is provided at the exit of the rotor bore (23), wherein the diffuser-shaped rotor bore exit (24) is designed to decelerate the cooling fluid flow
Implementation Method 2
cooling fluid (cooling air) is supplied by means of a rotor bore (19), which runs through the rotor (11) and is in fluid communication with said blade inlet (20)
Implementation Method 3
the area/shape of the rotor bore exit (19), which is cylindrical, and the inlet (20) of the blade, which is race-track shaped, are different, leading to a noncontinuous interface (see Fig. 3, the common area is shaded). The consequences of this design are: (a) The flow accelerates through the relatively small common area between the exit of the rotor bore (19) and the blade inlet (20). This produces flow separation near the blade inlet (20), leading to local low values of the internal heat transfer coefficient.
Data Source
Figure 1~3
Figure 4
Figure 5~6
AI summary
In a gas turbine with a rotor (11) and a blade (10) is attached to said rotor (11), wherein said blade (3) comprises an airfoil (14), a blade root (12) at the lower end of said airfoil (14) provided for being removably received by a groove (31) in said rotor (11), and a hollow blade core (18) arranged within said airfoil (14) and extending along the longitudinal axis (X) between said blade root (12) and said blade tip (15), for the flow of a cooling fluid, which enters said blade core (18) through a blade inlet (20) at said blade root (12), and is supplied by means of a rotor bore (23), which runs through the rotor (11) and is in fluid communication with said blade inlet (20) of said blade, whereby said blade inlet (20) has a cross section area which exceeds the cross section area of said rotor bore (23) in at least one direction, said rotor bore (23) having a diffuser-shaped rotor bore exit (24), such that the cross section area of the rotor bore exit (24) at the interface between rotor bore (23) and blade inlet (20) covers the cross section area of the blade inlet (20).