Centerbody Ram Air Duct Layout for CAC Motor Cooling Flow
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Solution Overview
Problem
Existing aircraft cabin air compressor (CAC) motor cooling systems face challenges in achieving optimal pressure differentials for enhanced cooling airflow, despite topology and shape optimizations of internal and external passages in the CAC motor cooling exhaust duct and outlet.
Innovation Solution
The introduction of a ram air assembly with a centerbody positioned in the ram air duct upstream of the fan inlet, which acts as an ejector to increase the velocity and mass flow rate of CAC motor cooling air by reducing the static pressure at the CAC return duct outlet, while maintaining ram air flow performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If topology and shape optimization of internal and external passages of CAC motor cooling exhaust duct and outlet is performed, then CAC head loss is reduced and cooling flow is improved, but additional cooling effectiveness is still desired
Solution Approach 1:
The invention introduces a centerbody that segments the ram air duct flow into distinct regions: a core flow region and outer bypass regions. This segmentation allows the core cooling air to be directed through the CAC motor while separate bypass flows manage pressure distribution, resolving the contradiction by creating specialized flow paths for different functions.
Solution Approach 2:
The centerbody acts as an intermediary structure between the ram air inlet and the CAC motor. It mediates the interaction between high-velocity cooling air and the ram air system by providing a structured path that maintains pressure differential while directing flow, thereby improving cooling effectiveness without increasing head loss.
2Quantity of substance
If pressure differential between CAC inlet and ram air system is increased to increase mass flow rate, then CAC motor cooling is improved, but system complexity increases
Solution Approach 1:
The centerbody performs multiple functions simultaneously: it directs core cooling air through the CAC motor, creates bypass regions for pressure management, and maintains the pressure differential needed for high mass flow rate. This multi-functionality achieves improved cooling without proportionally increasing system complexity.
Solution Approach 2:
The ram air assembly is designed to self-regulate the pressure differential and flow distribution through the centerbody geometry. The structure automatically balances cooling air delivery with ram air system requirements without additional control mechanisms, reducing complexity while maintaining high mass flow rate.
3Speed
If velocity of cooling air is increased to improve cooling effectiveness, then mass flow rate through CAC motor increases, but static pressure management becomes more difficult
Solution Approach 1:
The centerbody creates different flow conditions in different regions: high velocity core flow for cooling effectiveness and controlled pressure zones in bypass regions. This local differentiation of flow quality allows high velocity cooling air while managing static pressure through the bypass paths.
Solution Approach 2:
The invention manages pressure by adding a spatial dimension to flow management through the centerbody structure. Instead of uniformly managing pressure throughout the system, the centerbody creates three-dimensional flow paths with distinct pressure zones, allowing high velocity cooling air in the core while maintaining pressure balance through lateral bypass regions.
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 significant increase in CAC motor cooling airflow, enhancing cooling efficiency by increasing the mass flow rate and reducing static pressure, thereby improving CAC motor cooling effectiveness.
Implementation Method 1
acts as an ejector to increase the velocity and mass flow rate of CAC motor cooling air by reducing the static pressure
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A ram air fan inlet assembly for cabin air compressor (CAC) motor cooling flow enhancement includes a gas path defined by a ram air duct (14) and a fan section (18), a CAC motor cooling return duct (28) having an outlet (32) provided through a wall of the ram air duct, and a centerbody (34) body disposed in the ram air duct. The fan section is disposed immediately downstream and abutting the ram air duct. The ram air duct and fan section share a common axis. The centerbody is disposed about the common axis and configured to reduce of volume of the gas flow path in the ram air duct. The centerbody and the outlet axially overlap.