Aircraft Electric Motor Cooling via Aft Airflow
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Solution Overview
Problem
Conventional turbofan jet engines experience efficiency losses due to nonuniform airflow from boundary layer ingestion, which can negate benefits of improved propulsion efficiency, and there is a need for effective temperature management of aircraft propulsion system components.
Innovation Solution
An electric propulsion engine with a cooling system utilizing airflow over the aft end of an aircraft, featuring a closed loop with thermal transfer fluid and a heat exchanger, or a direct cooling airflow to manage the temperature of the electric motor, thereby maintaining efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If boundary layer ingestion systems are used to route slow moving air into turbofan jet engines, then propulsion efficiency is improved by reenergizing the boundary layer airflow, but the nonuniform velocity profile of the ingested air causes efficiency loss in the engines
Solution Approach 1:
The patent segments the airflow path by introducing a flow straightening section between the boundary layer ingestion system and the engine inlet. This section divides the distorted boundary layer flow into smaller streamtubes that are individually straightened, transforming the nonuniform velocity profile into a more uniform distribution suitable for engine intake while preserving the propulsion efficiency benefits of boundary layer ingestion.
2Adaptability or versatility
If electric propulsion engines are mounted at the aft end of the aircraft, then the cooling system can utilize airflow over the aft end for cooling, but the electric motor generates heat that requires active temperature management
Solution Approach 1:
The patent introduces a cooling system that acts as an intermediary between the electric motor and the ambient airflow. The system includes a heat exchanger coupled to the electric motor and a cooling fan that directs airflow over the heat exchanger, effectively transferring heat from the motor to the airflow and maintaining motor temperature within operational limits.
3Temperature
If conventional cooling systems are used for electric motors, then temperature management is achieved, but drag on the aircraft increases and net propulsive thrust is reduced
Solution Approach 1:
The patent merges the cooling system with the boundary layer ingestion system by integrating the flow straightening section to also serve as a cooling air intake pathway. The cooling fan utilizes the same airflow path as the propulsion system, and the heat exchanger is positioned to exploit the existing boundary layer flow, thereby achieving temperature control without adding separate drag-inducing cooling structures.
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 cooling system effectively manages the temperature of the electric motor, enhancing the propulsion efficiency and reducing drag, leading to improved net thrust and reduced energy dependency on secondary systems.
Implementation Method 1
a cooling system operable with an airflow over the aft end of the aircraft when the electric propulsion engine is mounted to the aircraft, the cooling system configured to cool the electric motor during operation of the electric propulsion engine
Implementation Method 2
a closed loop with thermal transfer fluid and a heat exchanger
Data Source
AI summary
A propulsion system for an aircraft includes an electric propulsion engine configured to be mounted at an aft end of the aircraft. The electric propulsion engine includes an electric motor and a fan rotatable about a central axis, the fan driven by the electric motor. The electric propulsion system additionally includes a cooling system operable with an airflow over the aft end the aircraft when the electric propulsion system is mounted to the aircraft. The cooling system is configured to cool the electric motor during operation of the electric propulsion engine.