Smooth Skin Exchanger for Aircraft Engine Cooling
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Solution Overview
Problem
Existing aircraft propulsion engine cooling systems, particularly those with high dilution ratios and reduction gearboxes, face challenges in reducing fuel consumption and engine thrust while maintaining effective cooling, as they often cause pressure losses and airflow disturbances when using finned heat exchangers or bleeding air from the secondary flow.
Innovation Solution
A smooth skin exchanger is housed between the fan and rectifier arms, utilizing the strong turbulence in this area for thermal exchanges between the fluid circuit and secondary air flow, without disturbing the airflow or increasing fuel consumption, and is designed to be curved to match the engine's exterior casing, maximizing heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If finned heat exchangers are used in the secondary air flow, then cooling capacity is improved, but pressure losses and airflow disturbances increase which reduce engine thrust
Solution Approach 1:
The invention extracts the cooling function from the main secondary air flow path by positioning the smooth skin exchanger on the outer casing where it can access secondary flow without obstructing the main airflow. This separates the cooling function from the thrust-generating flow, allowing both to operate effectively without mutual interference.
Solution Approach 2:
The smooth skin exchanger acts as an intermediary element that transfers heat from the lubricating oil to the secondary air flow without directly obstructing the airflow. It mediates between the thermal management requirement and the aerodynamic performance requirement by providing a thermal coupling surface that does not disrupt the flow field.
2Temperature
If air is bled from the secondary flow for cooling, then cooling effectiveness is improved, but fuel consumption increases
Solution Approach 1:
The system uses the existing secondary air flow that would otherwise be wasted or underutilized for the cooling function. The smooth skin exchanger captures thermal energy from this ambient secondary flow without requiring additional energy input or bleeding air from the system, making the cooling process self-sufficient and energy-neutral.
Solution Approach 2:
The secondary air flow serves dual functions: it provides thrust through the engine's bypass flow and simultaneously serves as the cooling medium for the lubricating oil through the smooth skin exchanger. This multi-functionality eliminates the need for separate cooling air extraction, reducing overall energy consumption.
3Temperature
If the cooling system is oversized for high power transmission, then cooling capacity is sufficient, but device complexity and footprint increase
Solution Approach 1:
The invention merges the cooling system with the engine's existing outer casing structure. The smooth skin exchanger is integrated into the nacelle's outer shell, utilizing the existing structural envelope rather than adding separate cooling components. This integration eliminates the need for additional space and reduces overall system complexity.
Solution Approach 2:
The smooth skin exchanger utilizes a thin-film or shell-like structure that conforms to the outer casing geometry. This flexible, surface-based design provides large heat transfer area without increasing volumetric footprint, allowing adequate cooling capacity within the constrained space of high-bypass engines.
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 enhances cooling capacity, reduces the impact on engine performance and fuel consumption, and increases engine thrust by leveraging the turbulent air flow for efficient heat exchange, making it suitable for high-dilution ratio engines and reduction gearboxes.
Implementation Method 1
utilizing the strong turbulence in this area for thermal exchanges between the fluid circuit and secondary air flow
Implementation Method 2
allows heat exchanges between the fluid of the fluid circuit and the air of the secondary flow
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a system for cooling a fluid of a lubrication circuit (20) of a propulsion engine (10) of an aircraft comprising a nacelle (11) which extends in a longitudinal direction (X) between an air inlet (12) and an ejection nozzle (13), a turbomachine (14) comprising a casing (15) attached to the inside of said nacelle by straightening arms (16), and a blower (17) which is arranged at said air inlet (12) of said nacelle, upstream of said turbomachine (14), and configured to be able to generate a flow of primary air supplying said turbomachine and a flow of secondary air supplying a channel, referred to as a secondary channel (18), formed between said nacelle (11) and said casing (15) of said turbomachine, characterised in that said cooling system comprises a skin exchanger (30) arranged on a wall inside said nacelle (11), longitudinally between said air inlet (12) of said nacelle and said straightening arms (16), said skin exchanger being in fluid communication with said lubrication circuit and configured to be able to ensure heat exchanges between said lubrication fluid and the air circulating in said secondary channel.