Constricted Duct for Stabilizing Gas Turbine Cooling Flow
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Solution Overview
Problem
Existing gas turbine engine rotor shroud cooling designs face challenges due to unsteady pressure fluctuations caused by rotor blade motion, leading to uneven coolant distribution and potential ingestion into film cooling holes, which reduces cooling effectiveness and increases heat load on critical areas.
Innovation Solution
A component with a duct that includes a constriction, reducing the cross-sectional area from the inlet to the outlet, helps stabilize the flow rate of cooling air and prevent ingestion by controlling pressure wave reflections, thereby enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If film cooling holes are used to cool the rotor shroud, then cooling effectiveness is improved, but unsteady pressure fluctuations cause large variations in coolant mass flow rate and potential ingestion
Solution Approach 1:
The duct geometry is designed with a varying cross-sectional area that changes along its length, allowing the flow area to dynamically respond to pressure fluctuations. This dynamic geometry adjustment stabilizes the coolant mass flow rate despite unsteady pressure conditions in the turbine environment
Solution Approach 2:
The duct cross-sectional area parameter is varied along the flow direction, creating a non-uniform geometry that modifies flow characteristics. This parameter change compensates for pressure fluctuations and maintains stable coolant flow rate throughout operating conditions
2Reliability
If the duct cross-sectional area is reduced from inlet to outlet, then coolant flow rate variation is reduced, but pressure drop across the duct increases
Solution Approach 1:
The duct geometry is designed with different cross-sectional areas at different locations, creating local variations in flow properties. The cross-sectional area is specifically reduced in the downstream region where it is most effective at stabilizing flow against outlet pressure fluctuations, while maintaining larger area at the inlet to minimize overall pressure drop
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
The component effectively reduces variations in coolant flow rate and minimizes ingestion, ensuring more consistent cooling across the rotor shroud surface, even under high heat and pressure fluctuations.
Implementation Method 1
the duct includes an inlet region having length L1 and flow area A1 and an outlet region having L2 with flow area A2 and a constriction (36) at which the duct decreases in cross-sectional area as it progresses from the inlet region to the outlet region
Data Source
AI summary
A component for releasing a flow of material into an environment subject to periodic fluctuations in pressure, which has: a first surface that includes an inlet; a second surface that includes an outlet; a duct formed in the component and extending from the inlet to the outlet so, when the component is in use, a flow of material received at the inlet can flow along the duct to be released at the outlet into an environment subject to periodic fluctuations in pressure. The duct includes a constriction at which it decreases in cross-sectional area as it progresses from the inlet to the outlet. This can help reduce the variation in flow rate of material released at the outlet caused by the periodic fluctuations in pressure, and may help to avoid/reduce ingestion, when the component is in use. Preferably, the component is configured to form part of a gas turbine engine.