Gas Turbine Ejector Cooling Central Cavity
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Solution Overview
Problem
Gas turbine engines face challenges in effectively cooling structural components within the central cavity surrounded by the exhaust diffuser due to high-temperature exhaust gases, which can lead to thermal damage.
Innovation Solution
The use of compressed air generated by the compressor to draw a large amount of cooling air into the central cavity, combined with an ejector system that utilizes the Bernoulli effect to draw in environmental air, creating a cooling air mixture that effectively cools the components by circulating through the exhaust channel and central cavity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cooling arrangements are used for structural components in the central cavity, then the components are protected from thermal damage, but the cooling effectiveness is insufficient due to limited cooling air supply
Solution Approach 1:
The invention utilizes pneumatic principles by employing a high-pressure air source from the compressor to drive ejectors. The ejectors convert the high-pressure air into high-velocity jets that create negative pressure zones, automatically drawing large quantities of cooling air into the central cavity without mechanical pumps or fans. This pneumatic system effectively solves the contradiction by using gas dynamics to amplify the cooling air supply.
Solution Approach 2:
The invention changes the pressure parameter of the cooling air supply by utilizing high-pressure air from the compressor (typically 3-10 bar) and converting it through ejectors into high-velocity flow. This parameter transformation enables the system to draw in large volumes of atmospheric air, converting a limited high-pressure air source into a abundant cooling air supply for the central cavity.
2Reliability
If expensive heat-resistant materials are used for structural components, then thermal protection is improved, but product cost increases
Solution Approach 1:
The invention extracts the thermal protection function from the material selection and relocates it to a dedicated cooling system. Instead of relying on expensive heat-resistant materials to withstand high temperatures, the system actively removes heat from structural components by circulating cooling air through the central cavity, thereby allowing the use of conventional, cost-effective materials.
Solution Approach 2:
The invention introduces cooling air as an intermediary substance between the high-temperature exhaust gases and the structural components. This cooling air acts as a thermal barrier, absorbing heat from the components and transporting it away, thereby protecting the components from thermal damage without requiring specialized heat-resistant materials.
3Reliability
If compressed air is used to draw cooling air into the central cavity, then cooling effectiveness is improved, but energy consumption increases
Solution Approach 1:
The ejector system is self-service in that it automatically draws cooling air into the central cavity using the kinetic energy of the compressed air jet, without requiring additional mechanical work input. The system utilizes the existing compressed air infrastructure of the gas turbine and converts its pressure energy into a self-sustaining cooling airflow, eliminating the need for separate cooling fans or pumps.
Solution Approach 2:
The invention merges the compressed air system (typically used for other engine functions) with the cooling system. The high-pressure air, already generated for combustion or control purposes, is diverted to drive the ejectors, thereby combining multiple functions into a single integrated system and avoiding the energy penalty of dedicated cooling equipment.
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 solution provides reliable and effective cooling of structural components, reducing the need for expensive heat-resistant materials and lowering product costs while ensuring efficient engine operation.
Implementation Method 1
an ejector system that utilizes the Bernoulli effect to draw in environmental air
Data Source
AI summary
A gas turbine engine has an exhaust diffuser. The diffuser has inner and outer cones both arranged coaxially with a central axis to define an annular exhaust channel there between and a central cavity within the inner cone. A first path is provided to extend radially through the outer and inner cones. The first path has a radially inward end and a radially outward end and the inward end s fluidly connected to the central cavity. An air supply is fluidly connected to the radially outward end of the first path, for supplying cooling air through the first path into the central cavity. An air supply or ejector is fluidly connected to the radially outward end of the first path, for drawing air by using the compressed air through the first path into the central cavity. A first opening is defined in the inner cone to fluidly connect between the exhaust channel and the central cavity. The first path and the first opening are so positioned that the cooling air is delivered from the air supply through the first path, the central cavity, and the first opening into the exhaust channel as it makes thermal contact with an object positioned in the central cavity to cool the object.