Gas Turbine Exhaust Eductor and Muffler System
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Solution Overview
Problem
Gas turbine engines face challenges in managing increased heat output and noise generation, particularly in auxiliary power units, which can disrupt aircraft operations and passenger comfort.
Innovation Solution
An exhaust system incorporating an eductor system that mixes primary exhaust fluid with a secondary cooling fluid to create a mixed fluid flow, which is then attenuated by a muffler system with baffles to reduce noise and increase cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the gas turbine engine operates to generate power, then power output increases, but heat output and noise levels increase
Solution Approach 1:
The patent converts the hot exhaust gases, which are harmful due to their temperature and noise, into a beneficial cooling resource. The exhaust system uses the hot exhaust flow to cool the lubrication fluid and engine compartment, transforming the harmful thermal energy into a useful cooling function.
Solution Approach 2:
The patent introduces secondary cooling fluid as an intermediary substance that transfers thermal energy from the exhaust system to the lubrication fluid and engine compartment. This intermediary enables heat exchange between the exhaust gases and the components needing cooling.
2Power
If the auxiliary power unit runs on the ground, then power is supplied for electrical systems, but noise disturbs passengers and personnel
Solution Approach 1:
The patent uses the hot exhaust gases, which carry significant thermal energy and noise, to provide cooling to the engine compartment and lubrication fluid. This converts the noisy, hot exhaust into a beneficial cooling resource that reduces overall system temperature while the power unit operates on the ground.
Solution Approach 2:
The exhaust system is divided into multiple ducts that are spaced apart about the circumference of the body, with each duct containing multiple eductor primary flow paths. This segmentation allows for distributed cooling throughout the engine compartment, improving cooling efficiency and noise distribution.
3Power
If the generator operates to meet increasing power needs, then electrical power increases, but temperature of lubricating fluid increases
Solution Approach 1:
The patent utilizes the hot exhaust gases to cool the lubrication fluid that becomes hot due to generator operation. The exhaust system acts as a heat exchanger, transferring thermal energy from the exhaust gases to the lubrication fluid, thereby converting the harmful heat into a useful cooling function.
Solution Approach 2:
The exhaust system serves multiple functions: it exits the combustive gases from the gas turbine engine, cools the lubrication fluid, cools the engine compartment, and attenuates sound. This multi-functionality allows a single system to address multiple problems simultaneously.
4Temperature
If the exhaust system cools the engine compartment and lubrication fluid, then temperature reduction occurs, but system complexity increases
Solution Approach 1:
The patent combines the exhaust function with the cooling function into a single integrated system. The exhaust ducts serve dual purposes: exiting combustive gases and providing cooling airflow to the engine compartment and lubrication fluid, thereby reducing the need for separate cooling systems.
Solution Approach 2:
The exhaust system uses its own hot exhaust gases to provide cooling, making the system self-sufficient. The thermal energy that would otherwise be wasted is utilized to cool the lubrication fluid and engine compartment, eliminating the need for external cooling resources.
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 system effectively reduces noise levels by 3 to 20 dB and enhances cooling, addressing the issues of heat and noise generated by gas turbine engines while maintaining low pressure losses.
Implementation Method 1
The eductor system is downstream from the turbine section to receive the primary fluid and is downstream from the source of the secondary fluid to receive the secondary fluid through a secondary inlet duct. The plurality of eductor primary flow paths extend through the secondary plenum such that the secondary fluid is drawn through the engine and generator oil cooler and mixed with the primary fluid via viscous action to generate the mixed fluid flow.
Implementation Method 2
The muffler system includes a plurality of baffles that cooperate to define a tortuous path for the mixed fluid flow and attenuate sound generated by the gas turbine engine.
Data Source
AI summary
A gas turbine engine includes a combustion section that generates combustive gases that form a primary exhaust flow and an exhaust system downstream from the combustion section. The exhaust system includes an eductor system that includes a body that extends along a first axis, and a plurality of ducts spaced apart about a circumference of the body. Each of the plurality of ducts define a plurality of eductor primary flow paths that terminate in a mixing chamber. The exhaust system includes a muffler system downstream from the mixing chamber that includes a plurality of baffles that cooperate to define a tortuous path and attenuate sound generated by the gas turbine engine. The exhaust system includes a housing that surrounds the eductor system and the muffler system such that the eductor system and the muffler system are contained within the housing.