Passive Flow Modulation Rings for Turbine Cooling Air Pressure Control
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Solution Overview
Problem
Existing gas turbine engines face challenges in maintaining desired temperature levels and pressure ratios of cooling air flow to high pressure turbine rotors, making it difficult to effectively cool these components.
Innovation Solution
A passive flow modulation device using differential variable-area radial inducers is employed, comprising rings with mismatched thermal expansion coefficients to adjust airflow passages based on temperature changes, allowing for dynamic adjustment of airflow to match rotor blade needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If active control systems are used to manage cooling air flow, then temperature and pressure ratio control is improved, but device complexity increases
Solution Approach 1:
The inducer assembly automatically adjusts cooling air flow based on temperature-driven differential thermal expansion between the outer ring and inner ring, eliminating the need for external actuators, sensors, or control systems. The system self-regulates by exploiting the natural thermal expansion properties of materials with different coefficients of thermal expansion.
Solution Approach 2:
The invention utilizes differential thermal expansion between the outer ring (higher coefficient) and inner ring (lower coefficient) to passively modulate the flow area of cooling air passages. As temperature changes, the rings expand at different rates, automatically adjusting the flow area to maintain optimal cooling conditions without active control.
2Temperature
If cooling air flow is increased to maintain temperature levels, then cooling effectiveness is improved, but pressure losses increase
Solution Approach 1:
The inducer assembly dynamically adjusts the flow area of cooling air passages in response to temperature changes through differential thermal expansion. This dynamic adjustment optimizes the balance between cooling effectiveness and pressure losses by matching the flow area to the actual thermal conditions of the turbine rotor.
Solution Approach 2:
The invention changes the physical parameter of flow area through thermal expansion of the rings. As temperature increases, the differential expansion automatically modifies the flow area to maintain optimal pressure ratio and cooling effectiveness, preventing excessive pressure losses while ensuring adequate cooling.
3Device complexity
If fixed flow area passages are used, then device complexity is reduced, but adaptability to varying temperature conditions deteriorates
Solution Approach 1:
The invention employs rings with different coefficients of thermal expansion that automatically adjust the flow area in response to temperature changes. The outer ring with higher expansion coefficient and the inner ring with lower expansion coefficient create a passive adaptation mechanism that modifies cooling air flow to match varying thermal conditions without complex control systems.
Solution Approach 2:
The flow passage structure transitions from a fixed geometry to a dynamic geometry that automatically adapts to temperature changes. The differential thermal expansion of the rings creates a self-adjusting flow area that responds to varying thermal conditions, improving adaptability while maintaining structural simplicity.
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 solution maintains optimal pressure ratios and reduces airflow requirements, improving specific fuel consumption and reducing pressure losses while eliminating the need for active control systems.
Implementation Method 1
the outer ring with a higher coefficient of thermal expansion than the second ring. In operation, the outer ring is configured to expand at a first rate in response to a transfer of thermal energy between the airflow and the outer ring. The second ring is configured to expand at a second rate in response to the transfer of thermal energy
Data Source
AI summary
A passive flow modulation device for a machine defining an axial direction and a radial direction, the passive flow modulation device including: a first ring with a first coefficient of thermal expansion; a second ring disposed coaxially with the first ring and positioned at least partially inward of the first ring along the radial direction, spaced from the first ring along the axial direction, or both, the first ring, the second ring, or both defining at least in part one or more passages, the second ring with a second coefficient of thermal expansion that is less than the first coefficient of thermal expansion to passively modulate a size of the one or more passages during operation.