Multi-Mode Heat Rejection for Turbine Engine Airflow Control

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Solution Overview

Problem

Existing gas turbine engines face challenges in optimizing thermal and propulsive efficiencies through effective thermal management systems, particularly in managing airflow and heat exchange within the engine's thermal management system.

Innovation Solution

A variable heat exchanger array with adjustable thermal absorption capacity, controlled by movable vanes and actuators, allows for tailored airflow distribution and pressure drop adjustment to optimize cooling based on engine operating conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed heat exchanger array is used, then the structure is simple, but the thermal management system cannot adapt to varying engine operating conditions

Engineering Contradiction:
Improveadaptability to varying engine operating conditionsVSAvoidstructure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies the dynamics principle by making the heat exchanger array variable rather than fixed. The heat exchanger can be moved between different positions (e.g., retracted and extended) to adapt to varying engine operating conditions. This allows the thermal management system to optimize heat exchange efficiency based on actual engine requirements while maintaining a relatively compact structure when not in use.

Inventive Principle:
Principle #15Dynamics

2Reliability

If airflow is increased through heat exchangers, then thermal management efficiency improves, but propulsive efficiency may be compromised

Engineering Contradiction:
Improvethermal management efficiencyVSAvoidpropulsive efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system dynamically adjusts the heat exchanger position and airflow distribution based on engine operating conditions. During high thermal management demand, the heat exchanger is positioned to maximize heat exchange while maintaining acceptable propulsive efficiency. During propulsive efficiency-critical operations, the system reduces heat exchanger engagement or adjusts airflow to prioritize thrust generation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes operational parameters such as heat exchanger position, airflow distribution ratios, and thermal absorption capacity to balance thermal management and propulsive efficiency. By varying these parameters based on real-time engine conditions, the system optimizes the trade-off between cooling performance and thrust generation.

Inventive Principle:
Principle #35Parameter changes

3Temperature

If thermal absorption capacity is increased, then heat rejection improves, but the system complexity increases

Engineering Contradiction:
Improveheat rejection capacityVSAvoidsystem complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The variable heat exchanger array serves multiple functions: it provides thermal management, can be retracted to minimize drag, and can be positioned to optimize heat exchange based on operating conditions. This multi-functionality allows a single component to handle various thermal management scenarios without requiring multiple separate systems, thereby limiting the increase in overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

Enhances thermal and propulsive efficiencies by optimizing airflow through heat exchangers, balancing thermal management requirements with propulsive engine performance.

Implementation Method 1

a variable heat exchanger array with adjustable thermal absorption capacity

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 2

optimizing airflow through heat exchangers

Methodology Applied
Scientific EffectThermal convection: Convection

Implementation Method 3

controlled by movable vanes and actuators, allows for tailored airflow distribution

Methodology Applied
Scientific EffectFluid flow control:

Implementation Method 4

The aft flow control device comprises a first vane disposed on a first side of the outlet, and a second aft vane disposed on a second side of the outlet. The first vane and the second vane are moveable between a first position defining a diverging nozzle through the passage and a second position defining a diverging nozzle of airflow exiting the at least two heat exchangers.

Methodology Applied
Scientific EffectDiffusion: Diffusion

Data Source

PatentEP3969730B1Multi-mode heat rejection system
Publication Date: 2025.10.08 RTX CORP
  • EP3969730B1 patent drawingFigure 1
  • EP3969730B1 patent drawingFigure 2
  • EP3969730B1 patent drawingFigure 3

AI summary

A turbine engine includes a duct defining an annular passage, at least two heat exchangers arranged within the annular passage and spaced circumferentially apart, a passage between the at least two heat exchangers, and a forward flow control device operable for controlling airflow through the passages.