Multi-nozzle Ejector for Turbine Cooling Air Entrainment
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Solution Overview
Problem
Existing systems for cooling and sealing in turbine engines are inefficient due to suboptimal compressor air diversion, which limits the pressure and temperature reduction of the diverted air, affecting overall turbine efficiency.
Innovation Solution
A multi-nozzle ejector system is used in a crossover flow path to enhance the entrainment of low-pressure air by high-pressure air, utilizing the momentum of high-pressure air through multiple nozzles to increase the surface area for interlayer drag, improving the entrainment ratio and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If compressed air is diverted from the earliest possible stage of the compressor, then the temperature and compressor work of the diverted air are reduced, improving overall turbine efficiency, but the pressure required to drive the cooling and sealing systems increases
Solution Approach 1:
The compressor air extraction system is segmented into multiple extraction stages with separate flow paths. A first extraction circuit diverts air from an earlier stage while a second extraction circuit diverts air from a later stage, allowing independent optimization of each path's pressure and temperature characteristics for different cooling and sealing requirements.
Solution Approach 2:
An ejector system is introduced as an intermediary device between the extraction circuits and the turbine. The ejector uses a high-pressure air stream to create a low-pressure zone that entrains and mixes with the extracted air, effectively reducing the pressure requirement while maintaining the cooling effect.
2Productivity
If a single ejector system is used to combine high and low pressure air, then the structure is simple, but the entrainment efficiency is insufficient
Solution Approach 1:
The ejector system is segmented into multiple nozzles arranged in a circular pattern. Each nozzle creates its own jet stream that contributes to the overall entrainment effect, increasing the total surface area for momentum transfer and improving low-pressure air entrainment efficiency.
Solution Approach 2:
The ejector design transitions from a single-point injection to a distributed circular arrangement of nozzles. This two-dimensional distribution increases the effective area for momentum transfer and creates multiple flow interaction zones, significantly enhancing entrainment efficiency.
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 results in a five percent gain in overall efficiency by effectively combining high and low-pressure air streams, achieving improved cooling performance and reducing compressor work invested in diverted air.
Implementation Method 1
utilizing the momentum of motive flow of the high pressure air through a nozzle to create a suction flow of low pressure air surrounding the nozzle
Implementation Method 2
Interlayer shear operates between the high and low pressure air flow streams within the ejector system resulting in entrainment (suction flow) of the low pressure air with the high pressure flow stream
Data Source
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AI summary
An ejector system (34) and method of operation for combining high and low pressure fluid flow streams (18) is disclosed. A nozzle chamber (35) communicates with a high pressure fluid flow stream and a suction chamber (42) communicates with a low pressure fluid flow stream (18). The outlet (40) of the nozzle chamber (35) exit into the suction chamber (42) and include multiple nozzles (48) such that the high pressure flow stream exits the nozzle chamber (35) in multiple flow streams having multiple surface areas for interlayer drag between the flows. The low pressure fluid flow stream (18) is entrained by the high pressure fluid flow streams exiting the multiple nozzles (48) to define an intermediate pressure flow stream.