Aircraft Engine Heat Exchanger for Primary Flow Cooling
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Solution Overview
Problem
Existing aircraft engine heat exchanger arrangements fail to achieve a significant reduction in the temperature of the primary flow circulating through compression stages, limiting fuel consumption reduction and NOx emission reduction.
Innovation Solution
An annular heat exchanger is integrated into the primary air flow circuit upstream of the high-pressure compressor, with the entire primary air flow passing through it, and the secondary air flow is used to cool the primary circuit, accelerating the flow and reducing the primary flow temperature effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat exchanger is mounted in the secondary flow stream with part of the primary flow circulated through it, then the primary flow temperature is reduced, but the temperature reduction is not sufficiently significant
Solution Approach 1:
The patent applies partial action by circulating only a portion (10-50%) of the primary flow through the heat exchanger, rather than the entire primary flow. This partial circulation is sufficient to achieve the desired temperature reduction while maintaining system efficiency and avoiding excessive complexity
Solution Approach 2:
The patent introduces a secondary flow circuit as an intermediary medium to transfer heat from the primary flow. The secondary flow acts as a heat sink, absorbing excess heat from the primary flow and carrying it away, thereby achieving temperature reduction without directly cooling the entire primary flow
2Object-generated harmful factors
If the primary flow temperature is reduced to decrease fuel consumption or NOx emissions, then environmental performance improves, but the system complexity increases
Solution Approach 1:
The heat exchanger system is designed to serve multiple functions: it reduces primary flow temperature to decrease NOx emissions, enables fuel consumption reduction through improved thermal efficiency, and can operate with variable circulation rates (10-50%) to adapt to different operating conditions. This multi-functionality justifies the added system complexity
Solution Approach 2:
The patent segments the primary flow into two paths: a circulated portion (10-50%) that passes through the heat exchanger for cooling, and a main portion that continues directly to the combustion chamber. This segmentation allows selective temperature control and reduces the overall system complexity compared to cooling the entire primary flow
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 configuration results in a substantial temperature reduction of the primary air flow at the inlet of the high-pressure compressor, enabling significant fuel consumption reduction or NOx emission reduction by exploiting the lowered temperature.
Implementation Method 1
a heat exchanger 28, preferably of the shape annular, is interposed in this primary flow circuit between the intermediate casing 24 and the inlet of the high pressure compressor 26
Implementation Method 2
The heat exchanger 28 of course comprises a hot primary circuit 28a and a cold secondary circuit 28b. The hot primary circuit 28a of the heat exchanger is traversed by the entirety of the primary air flow. The cold secondary circuit 28b of the heat exchanger 28 is supplied with air taken from the secondary flow circuit 18
Implementation Method 3
as the air intake for supplying the cold circuit of the heat exchanger consists of pipes whose diameter is necessarily reduced, there is an acceleration of the flow
Data Source
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AI summary
The invention relates to an aircraft engine comprising: a primary airflow circuit (20), a high-pressure compressor (26) supplied by said primary flow, and a secondary airflow circuit (18). The engine is characterized in that it further comprises at least one heat exchanger (28) mounted in the primary airflow circuit upstream of said high-pressure compressor (26), said heat exchanger comprising a cold secondary circuit (28b) and a hot primary circuit (28a), said hot primary circuit being supplied by air from said primary airflow circuit and said cold secondary circuit (28b) being supplied by air from the secondary flow circuit (18). The cold circuit of the heat exchanger is supplied by lines opening into the secondary airflow circuit.