Modulated Air-Cooled Heat Exchanger for Hybrid Engine Drag Control

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Solution Overview

Problem

The integration of hybrid electric systems in gas turbine engines leads to challenges in managing system waste heat, as traditional methods of increasing heat exchanger size to handle increased heat result in significant drag losses during cruise.

Innovation Solution

A modulated air-cooled heat exchanger with a controllable inlet door that adjusts airflow to manage heat transfer efficiently, reducing drag losses by dynamically controlling airflow through the heat exchanger.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If the size of heat exchanger is increased to reject system waste heat in low air-flow operating conditions, then heat management capacity is improved, but drag losses increase at cruise

Engineering Contradiction:

Improveheat management capacityVSAvoiddrag losses

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The inlet door is made movable and adjustable, allowing the heat exchanger to dynamically modulate airflow according to operating conditions. The door can be positioned at different angles to control the amount of air entering the heat exchanger, enabling adaptation between high heat rejection needs at idle and low drag requirements at cruise

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the airflow parameter dynamically by adjusting the inlet door position. At ground idle, the door is fully open to maximize airflow and heat rejection. At cruise conditions, the door is partially closed to reduce airflow and minimize drag losses, while still maintaining adequate heat management capability

Inventive Principle:

Principle #35Parameter changes

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 modulated air-cooled heat exchanger reduces nacelle drag losses and maintains efficient heat management with minimal weight impact, adapting to varying operational conditions.

Implementation Method 1

The fan section is configured to generate an airflow

Methodology Applied

Scientific EffectMechanical force: Mechanical Force

Implementation Method 2

The heat exchanger is configured to transfer heat from a thermal management system to the airflow

Methodology Applied

Scientific EffectHeat transfer: Heat Exchanger

Data Source

PatentEP4650585A1Modulated air-cooled heat exchanger for hydrid electric thermal management systems

Publication Date: 2025.11.19 RTX CORP

Figure 1
Figure 2A~2B
Figure 3A~3B

AI summary

A gas turbine engine (100) includes a fan section (102), a heat exchanger (116), and inlet door (122). The fan section (102) is configured to generate an airflow. The heat exchanger (116) is configured to transfer heat from a thermal management system (114) to the airflow. The inlet door (122) is configured to modulate the airflow to the heat exchanger (116).