Dual Inlet Precooler System for Aircraft Engine Nacelle
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Solution Overview
Problem
Current aircraft engine precooler systems disrupt air flow through the fan duct during low-flow or no-flow states, leading to undesired spillage and reduced aerodynamic performance, and face challenges in mounting larger precoolers due to space constraints within the engine nacelle.
Innovation Solution
The implementation of an inlet system with two separate inlets and ducts, each with a swept leading edge, allows for reduced air flow disruption and enables the precooler to be mounted further forward, reducing duct length and minimizing spillage by equalizing total pressure along the leading edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a single inlet is used to supply air to the precooler, then the duct length must be increased to reach the precooler, but this increases the disruption to air flow through the fan duct and causes undesired spillage
Solution Approach 1:
The single inlet is divided into two separate inlets (first inlet and second inlet), each with its own duct. This segmentation allows the precoolers to be positioned closer to the fan, reducing the required duct length and minimizing disruption to the fan duct airflow, thereby reducing total pressure losses.
2Volume of stationary object
If the precooler is mounted further aft to accommodate longer ducts, then space is available, but aerodynamic performance decreases due to increased spillage and pressure losses
Solution Approach 1:
By segmenting the inlet system into two separate inlets and ducts, the precoolers can be mounted in positions that optimize both space utilization and aerodynamic performance, eliminating the need to mount precoolers far aft.
3Productivity
If air flow into the precooler is reduced to low-flow or no-flow state during cruise, then cooling is not needed, but the inlet disrupts the fan duct air flow more than desired causing spillage
Solution Approach 1:
The leading edges of the inlets are designed with specific sweep angles (first angle and second angle relative to normal axes) to equalize total pressure locally along the leading edges. This local pressure equalization prevents spillage and maintains aerodynamic performance even when airflow to the precooler is reduced or stopped during cruise conditions.
4Adaptability or versatility
If a valve system is used to control air flow to the precooler, then cooling can be regulated, but the inlet configuration still causes undesired spillage during low-flow states
Solution Approach 1:
The swept leading edge design with specific angle relationships creates local pressure equalization that works in conjunction with valve systems to prevent spillage during all flow conditions, including low-flow and no-flow states when the valve is partially or fully closed.
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 improves aerodynamic performance by reducing total pressure losses and static pressure distortion, allowing for larger precoolers to be installed closer to the engine inlet, enhancing the engine's cooling capacity while maintaining efficient airflow.
Implementation Method 1
A heat exchanger in the precooler then uses the diffused air to cool the bleed air.
Implementation Method 2
Each of the first inlet and the second inlet may include a swept leading edge. The leading edge of each inlet may have a first angle relative to a first normal axis that is substantially normal to a direction of air flow through a fan duct in the engine system and a second angle relative to a second normal axis that is substantially normal to the direction of the air flow. The swept leading edge may equalize total pressure along the leading edges of the inlets, which may reduce air flow disruption and spillage.
Data Source
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AI summary
A method and apparatus for supplying air to a precooler (1417). Air flow is created through a fan duct in an engine system. A first portion of the air flow is directed into a first inlet (1428) of an inlet system (1416) to feed a first half of the precooler (1417). A second portion of the air flow is directed through the fan duct into a second inlet (1441) of the inlet system to feed a second half of the precooler (1417).