Ram Air Cooled Intercooler for Gas Turbine Engine

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Solution Overview

Problem

Conventional intercooling methods in gas turbine engines, such as using water or heat exchangers with bypass airflow, face limitations due to pressure losses and the thermal capacity of fuels like kerosene, which restrict the effectiveness of intercooling in reducing the work input required for compression and increasing engine thrust.

Innovation Solution

The engine employs a heat exchanger cooled by the fluid flow generated by the conveyance's movement, which is strategically mounted on external surfaces and can be selectively operated to control cooling, reducing frictional drag and optimizing intercooling by using multiple heat exchangers cooled by air, fuel, and bypass airflow, minimizing pressure losses and enhancing thermal efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a heat exchanger is used for intercooling between the first and second pressure compressors, then the work input required at the second pressure compressor is reduced, but pressure losses occur on both the core engine airflow side and the bypass airflow side

Engineering Contradiction:

Improvework input at second pressure compressorVSAvoidpressure losses

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The heat exchanger utilizes the aircraft's own forward motion through the air to provide cooling, eliminating the need for separate cooling fans or pumps. The ram air flow generated by the aircraft's velocity self-cools the intercooler, converting the aircraft's kinetic energy directly into cooling capacity without additional energy consumption or pressure losses.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The heat exchanger is positioned on the external surface of the aircraft, utilizing the third dimension (external space) for heat dissipation. This external positioning allows the cooling function to be performed by the aircraft's motion through the air, separate from the internal airflow paths, thereby avoiding pressure losses in both the core engine and bypass airflow systems.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Temperature

If the heat exchanger is positioned to maximize cooling effect, then intercooling performance improves, but frictional drag of the conveyance increases

Engineering Contradiction:

Improvecooling effectVSAvoidfrictional drag

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The heat exchanger is positioned at specific locations on the aircraft external surface where the local airflow characteristics provide optimal cooling while minimizing drag. The design utilizes areas with favorable flow patterns that enhance heat transfer coefficients without creating significant pressure drag or flow separation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The heat exchanger design allows for adjustment of parameters such as surface area, orientation, and configuration to optimize the balance between cooling effect and drag. By varying these parameters, the system can adapt to different flight conditions and maintain optimal performance across a range of speeds and temperatures.

Inventive Principle:

Principle #35Parameter changes

3Temperature

If fuel is used as a coolant in the combustor, then some intercooling is achieved, but the thermal capacity of kerosene severely limits the amount of intercooling possible

Engineering Contradiction:

Improveintercooling capacityVSAvoidfuel thermal capacity

Core Design Contradiction:

TemperatureVSQuantity of substance

Solution Approach 1:

The invention introduces ram air as an intermediary cooling medium between the compressed air and the combustor. Instead of relying solely on fuel's thermal capacity, the system uses the external air flow (mediated by the heat exchanger) to absorb heat from the compressed air, thereby achieving intercooling without consuming additional fuel and overcoming the limitation of fuel's thermal capacity.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 effectively reduces frictional drag and improves engine fuel economy by optimizing intercooling, allowing for higher compressor delivery pressures and increased thrust while minimizing pressure losses, making it suitable for supersonic flight conditions.

Implementation Method 1

the intercooling means including a heat exchanger, the heat exchanger arranged to be cooled by a flow of the fluid generated by the relative movement of the conveyance through the fluid

Methodology Applied

Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

the heat exchanger heats the flow of fluid to reduce the frictional drag

Methodology Applied

Scientific EffectThermal boundary layer modification: Boundary Layer

Data Source

PatentUS7716913B2Engine

Publication Date: 2010.05.18 ROLLS ROYCE PLC

AI summary

An engine (110, 210) for moving a conveyance (132) through a fluid includes first and second pressure creating means (13, 14) for pressurising an engine airflow, and intercooling means (116, 290, 292) for cooling the engine airflow between the first and second pressure creating means (13, 14). The intercooling means (116, 290, 292) includes a heat exchanger (116) which is arranged to be cooled by a flow of the fluid generated by the relative movement of the conveyance (132) through the fluid.