Annular Plenum Chamber for Turbine Inter-stage Cooling
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Solution Overview
Problem
In gas turbine engines, the efficiency of coolant air flow between turbine stages is compromised due to increased pressure losses and seal wear, leading to ineffective cooling and potential hot gas ingestion, especially as engine size and operating temperatures rise.
Innovation Solution
An annular plenum chamber with strategically designed outlets and seals is used to control coolant flow into the inter-stage cavity, featuring angled and variable diameter outlet holes, and integrated discourager seals to minimize hot gas ingestion, while allowing efficient coolant delivery to turbine stages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If coolant air flow is increased to improve cooling effectiveness, then cooling performance is improved, but pressure losses increase and engine efficiency decreases
Solution Approach 1:
The patent applies local quality by providing targeted cooling only where needed through strategically positioned outlet holes in the plenum chamber. The coolant is delivered directly to specific regions requiring cooling (such as disc surfaces and blade roots) rather than distributing it universally, thereby improving cooling effectiveness while minimizing overall coolant flow requirements and associated pressure losses.
Solution Approach 2:
The plenum chamber acts as an intermediary device between the coolant supply and the turbine components. It receives coolant from the supply, distributes it through controlled outlets to various cooling locations, and manages the pressure differentials. This intermediary structure enables efficient coolant distribution with reduced pressure losses compared to direct delivery systems.
2Reliability
If seal clearances are increased to accommodate wear during service cycles, then reliability is maintained, but hot gas ingestion increases
Solution Approach 1:
The patent incorporates feedback mechanisms through pressure differential control between the plenum chamber and inter-stage cavity. The system responds to changing conditions (such as seal wear and clearance variations) by adjusting the pressure balance, ensuring that coolant flow maintains effective sealing at the rim gap even as clearances increase during service cycles. This prevents hot gas ingestion while accommodating normal wear.
Solution Approach 2:
The plenum chamber is designed to pre-establish appropriate pressure differentials before coolant is delivered to the cooling outlets. By controlling the pressure environment in advance within the plenum chamber, the system ensures that sufficient coolant flow reaches the sealing regions to prevent hot gas ingestion, even as seal clearances increase during engine service cycles.
3Object-affected harmful factors
If coolant flow is directed to seal the rim gap, then hot gas ingestion is prevented, but coolant flow to downstream regions is reduced
Solution Approach 1:
The patent segments the coolant distribution function by providing separate outlet holes in the plenum chamber for different cooling purposes. Some outlets are positioned to deliver coolant to the rim gap sealing region, while others deliver coolant to downstream disc surfaces and blade cooling regions. This segmentation allows independent optimization of coolant flow to each region, ensuring sufficient flow for sealing without compromising downstream cooling requirements.
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 enhances the control and effectiveness of coolant flow, reducing hot gas ingestion and maintaining engine efficiency by optimizing pressure differentials and seal performance, even as engines undergo service cycles and size increases.
Implementation Method 1
optimizing pressure differentials and seal performance
Implementation Method 2
integrated discourager seals to minimize hot gas ingestion
Implementation Method 3
The coolant may be swirled to complement the direction and speed of rotation of a rotor disc on delivery to the disc surface
Data Source
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AI summary
An apparatus for controlling flow of coolant into an inter-stage cavity (30) of a turbomachine is described. The cavity (30) is bounded by a first turbine stage (31), a second turbine stage (32) axially displaced along a common axis of rotation (A-A) with the first turbine stage (31), and an annular platform (34) bridging a space between the axially displaced first and second turbine stages (31, 32). An annular plenum chamber (35) is arranged inboard of the annular platform (34), the annular plenum chamber (34) having one or more inlets for receiving coolant and one or more outlets (44) exiting into the cavity (30), whereby, in use, coolant is delivered into the cavity (30) at an increased pressure compared to coolant entering the plenum chamber (35) at the inlet. The apparatus is beneficially arranged immediately upstream of an inter-stage seal assembly.