Tertiary-Flow Heat Exchanger Layout for Axial Turbomachines
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Solution Overview
Problem
Existing turbomachinery designs face performance penalties and efficiency losses due to the presence of heat exchangers in the secondary flow, which disrupt thrust and cause aerodynamic disturbances, and are vulnerable to foreign object impacts.
Innovation Solution
An axial turbomachine design with a heat exchanger positioned in the tertiary flow channel, featuring diverging heat exchange surfaces adjacent to structural arms, optimized for airflow speed to minimize bulk and aerodynamic interference, and incorporating a stator for flow straightening and a bypass for debris.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat exchanger is placed in the secondary flow to cool the oil, then the cooling function is achieved, but the thrust is dampened and aerodynamic disturbances occur
Solution Approach 1:
The invention divides the airflow into three separate flows: primary flow through the compressor, secondary flow from the fan, and tertiary flow created by a dedicated separation nozzle. The heat exchanger is placed in the tertiary flow channel, segmenting it from both the primary and secondary flows. This segmentation allows the heat exchanger to be positioned where it can cool the oil effectively without interfering with the thrust-generating secondary flow or the compression process.
Solution Approach 2:
The invention creates a new spatial dimension by introducing a tertiary flow channel that is radially external to the primary flow but separate from the secondary flow. The heat exchanger is positioned in this newly created tertiary dimension, allowing it to access cooling airflow without occupying space in the thrust-critical secondary flow path or the high-pressure primary flow path.
2Temperature
If a heat exchanger is placed in the secondary flow channel, then oil cooling is achieved, but significant aerodynamic disturbances and vibrations occur
Solution Approach 1:
The invention segments the airflow paths to create a dedicated tertiary flow channel for the heat exchanger, separating it from the secondary flow channel. This segmentation isolates the heat exchanger-induced aerodynamic disturbances to the tertiary flow only, preventing them from propagating into the secondary flow and causing vibrations and noise.
Solution Approach 2:
The tertiary flow acts as an intermediary medium between the fan-driven secondary flow and the heat exchanger. The separation nozzle creates this intermediate flow path that carries airflow to the heat exchanger, mediating the interaction between the thrust-generating flow and the heat exchange process, thereby isolating harmful aerodynamic effects.
3Power
If the heat exchanger is positioned upstream to avoid thrust disruption, then thrust is optimized, but the heat exchanger is vulnerable to foreign object impacts
Solution Approach 1:
The invention segments the airflow paths so that the heat exchanger operates in a dedicated tertiary flow channel that is downstream of the fan but separate from the direct fan outlet path. This segmentation allows the heat exchanger to be positioned in a location that maintains thrust efficiency while being protected from foreign objects that would otherwise directly impact upstream positioned components.
4Power
If a compact heat exchanger is used to maintain engine performance, then thrust is optimized, but cooling efficiency may be reduced
Solution Approach 1:
The invention applies local quality by creating a dedicated tertiary flow channel with specific flow characteristics optimized for heat exchange. The separation nozzle is designed to deliver airflow with appropriate velocity and pressure characteristics to the heat exchanger, ensuring efficient cooling in this localized region without compromising overall engine performance or requiring a large heat exchanger.
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
Enables efficient oil cooling with compact heat exchangers that maintain engine performance, reduce carbon emissions, and protect against foreign object damage, while optimizing thrust and reducing aerodynamic disturbances.
Implementation Method 1
an air/oil type heat exchanger disposed in the tertiary flow channel and comprising heat exchange surfaces with air and oil passages extending in said tertiary flow channel
Implementation Method 2
heat exchange surfaces with air and oil passages extending in said tertiary flow channel
Implementation Method 3
heat exchange surfaces with air and oil passages extending in said tertiary flow channel
Implementation Method 4
The axial turbomachine comprises a stator disposed in the tertiary flow vein and upstream of each structural arm
Implementation Method 5
the heat exchange surfaces have a diverging circumferential profile conforming to the downstream portions of the structural arms
Implementation Method 6
the presence of a heat exchanger in the secondary circuit negatively impacts the performance and overall efficiency of the turbomachine
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
Disclosed is an axial turbomachine (2) that comprises: a first splitter (10) capable of separating an incoming airflow (F) into a radially internal airflow (F') and a radially external airflow, referred to as secondary flow (F2); a second splitter (14) capable of separating the radially internal airflow into a primary flow (F1) and a tertiary flow (F3), said tertiary flow being in a tertiary stream (16) radially external to said primary flow; an air-to-oil heat exchanger (18) placed in the tertiary stream and including surfaces exchanging heat with the air and oil passages extending into said tertiary stream; and structural arms (60) extending radially through the tertiary stream. The axial turbomachine (2) is characterised in that each structural arm has, in the tertiary stream, a cross-section with a downstream portion (62) the width of which decreases downstream, the heat exchanger being adjacent to said downstream portions of the structural arms.