Boost Compressor Augmentation for Low-Airflow Heat Rejection
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Solution Overview
Problem
The integration of hybrid electric systems in gas turbine engines generates excess waste heat, particularly during low-airflow conditions like taxiing and idling, which existing heat exchanger solutions are unable to manage effectively without increasing weight and drag.
Innovation Solution
A boost compressor augmentation system redirects compressed air from existing air supplies to enhance airflow over heat exchangers during low-airflow conditions, using switching valves to optimize heat rejection without altering the heat exchanger architecture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the size of heat exchangers is increased to reject excess heat in low air-flow conditions, then heat management capacity is improved, but weight and drag increase
Solution Approach 1:
The system dynamically adjusts airflow to the heat exchanger using a variable speed fan and controllable valve, allowing the heat rejection capacity to be modulated according to actual thermal load rather than being fixed by oversized hardware. This enables adequate heat management during low-airflow conditions without permanently increasing system weight.
Solution Approach 2:
The invention changes the operating parameters of the existing heat exchanger by increasing airflow velocity through the use of a variable speed fan and valve control. By adjusting these parameters, the heat transfer coefficient and overall heat rejection capacity are enhanced temporarily during low-airflow conditions without modifying the physical size or weight of the heat exchanger.
2Temperature
If the size of heat exchangers is increased to reject excess heat in low air-flow conditions, then heat management capacity is improved, but drag increases
Solution Approach 1:
The system uses dynamic control of fan speed and valve position to optimize airflow through the heat exchanger only when thermal management is needed. This eliminates the need for permanently larger heat exchanger surfaces that would increase drag during all operating conditions, thereby reducing aerodynamic penalty while maintaining heat rejection capability when required.
Solution Approach 2:
By changing the airflow parameters (velocity, duration) through variable speed fan and valve control, the system achieves enhanced heat rejection during low-airflow conditions without increasing the physical footprint or drag coefficient of the heat exchanger assembly.
3Temperature
If a boost compressor is added to increase airflow through heat exchangers, then heat rejection capacity is improved, but device complexity increases
Solution Approach 1:
The variable speed fan serves multiple functions: it provides primary airflow for heat rejection, acts as a boost mechanism during low-airflow conditions, and can be controlled to optimize performance across different operating regimes. This multi-functionality eliminates the need for a separate boost compressor, reducing device complexity while achieving the desired heat rejection enhancement.
Solution Approach 2:
The existing fan system, when equipped with variable speed control and valve regulation, serves its own purpose of boosting airflow during low-airflow conditions without requiring an additional dedicated boost compressor. The system uses its existing components in a more flexible, controllable manner to achieve enhanced performance.
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
Effectively manages excess waste heat during low-airflow conditions without increasing weight or drag, maintaining efficient thermal management by leveraging existing air supplies.
Implementation Method 1
a first heat exchanger disposed in a second portion of the nacelle, where a fan stream passes through the second portion of the nacelle
Implementation Method 2
a boost compressor... The second switching valve is configured to direct gas to the boost compressor
Data Source
AI summary
A fan is disposed at an intake of a nacelle, and a gas turbine is contained within a first portion of the nacelle. The gas turbine includes compressor, combustor, and turbine stages through which a core stream of gas passes past the fan and past the compressor, combustor, and turbine stages. A first heat exchanger is disposed in a second portion of the nacelle, where a fan stream passes through the second portion of the nacelle. A first switching valve receives gas from the fan stream and directs the received gas to a second switching valve or the turbine stage. The second switching valve directs gas to a boost compressor and receives gas from the first switching valve or a high pressure bleed from the compressor stage. A third switching valve receives gas from the boost compressor and directs compressed gas to the first heat exchanger or the turbine stage.