Electric Machine Air Cooling in Aircraft Turbine Engines
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Solution Overview
Problem
Current cooling solutions for electric machines in aircraft turbomachines require additional oil cooling loops, which add complexity and weight, and do not efficiently manage thermal losses.
Innovation Solution
The implementation of elements configured to generate disturbances in the primary airflow within the turbomachine, such as concave curved or grooved surfaces and plasma actuators, to enhance the thermal exchange coefficient between the airflow and the electric machine, allowing for effective cooling without oil, by creating turbulence that renews cooling air and increases heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If additional oil cooling loops are used to cool the electric machine, then cooling effectiveness is improved, but device complexity and weight increase
Solution Approach 1:
The invention extracts and eliminates the oil cooling loop from the cooling system, relying solely on air cooling from the primary flow. The cooling function is achieved by introducing disturbance elements that enhance heat transfer coefficients, removing the need for the separate oil cooling subsystem and its associated complexity.
Solution Approach 2:
The primary flow, originally intended only for mechanical drive functions, is given a dual function by utilizing it for thermal cooling of the electric machine. The same air flow serves both propulsion purposes and cooling purposes, eliminating the need for dedicated cooling loops.
2Temperature
If additional oil cooling loops are used to cool the electric machine, then cooling effectiveness is improved, but weight increases
Solution Approach 1:
The invention extracts and eliminates the oil cooling loop from the cooling system, relying solely on air cooling from the primary flow. The cooling function is achieved by introducing disturbance elements that enhance heat transfer coefficients, removing the need for the separate oil cooling subsystem and its associated weight.
Solution Approach 2:
The primary flow serves itself dual purposes: mechanical drive and thermal cooling. By enhancing the heat transfer capability of the primary flow through disturbance elements, the system uses its own resources for cooling without requiring additional cooling media or separate cooling infrastructure.
3Temperature
If complete shaping of shell and blades is used to increase heat transfer, then cooling efficiency is improved, but pressure drop increases
Solution Approach 1:
Instead of completely reshaping the shell and blades, the invention introduces localized disturbance elements at specific positions where they can effectively enhance heat transfer. This localized approach increases the heat transfer coefficient without significantly affecting the overall flow characteristics and pressure drop.
Solution Approach 2:
The invention applies partial action by introducing disturbance elements only in specific regions rather than completely reshaping the entire shell and blade structure. This partial modification is sufficient to achieve the desired heat transfer enhancement while minimizing impact on pressure drop.
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 improves the cooling efficiency of the electric machine using only air from the primary flow, eliminating the need for oil cooling loops and reducing overall weight and complexity, while maintaining effective thermal management.
Implementation Method 1
elements configured to generate disturbances in the primary flow... The disturbances or turbulence set in motion the air near the surface of the shell and/or blades to be cooled
Implementation Method 2
The heated air does not stagnate and is turbulently drawn towards the cooler secondary flow before returning to the surface of the shell and/or blades to be cooled
Implementation Method 3
increase the heat transfer coefficient between the primary flow and the shell and/or blades, and therefore the heat exchange capacity between the primary flow and the electric machine
Data Source
Figure 1~2
Figure 3a~3b
Figure 4~5
AI summary
Disclosed is an aircraft turbine engine (10), comprising a gas generator (12) and a fan (14) arranged upstream from the gas generator (12) and configured to generate a gas inlet stream (F), part of which flows into a duct of the gas generator to form a primary stream (36), the turbine engine (10) comprising an electrical machine that is mounted coaxially downstream from the fan (14) and that comprises a rotor (62a) surrounded by a stator (62b) carried by an annular shroud (64), this shroud (64) being surrounded by a casing (40) of the gas generator that defines, with this shroud (64), a section of the flow duct for the primary stream (36), stationary vanes (42, 68) for straightening this primary stream (36) extending into this path.