Compressor Diffuser Relief Feature for Surge Margin
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Solution Overview
Problem
Air compressors in aircraft, such as cabin air compressors, experience degradation in effectiveness, efficiency, and lifespan when operated outside a preferred range of conditions due to varying pressures and temperatures.
Innovation Solution
A backing plate with a relief feature in the diffuser assembly of the air compressor allows a portion of the air to bypass the vanes, improving the surge margin and increasing the operating range, efficiency, and effectiveness of the compressor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the compressor operates outside the preferred range of conditions, then the compressor must handle varying pressures and temperatures, but the effectiveness, efficiency, and lifespan degrade
Solution Approach 1:
The diffuser vane is made movable relative to the diffuser wall, allowing the clearance between them to be dynamically adjusted. The vane can rotate about an axis to change its position, enabling the system to adapt to varying operating conditions (pressures and temperatures) while maintaining optimal performance and avoiding degradation
Solution Approach 2:
The invention changes the geometric parameter of the diffuser assembly by allowing variable clearance between the diffuser vane and diffuser wall. This parameter adjustment enables the compressor to maintain effectiveness and efficiency across a wider range of operating conditions
2Adaptability or versatility
If the diffuser vane is fixed relative to the diffuser wall, then the structure is simple, but the surge margin is limited and operating range is restricted
Solution Approach 1:
The diffuser vane is designed to be movable rather than fixed, allowing it to rotate about an axis to adjust the clearance with the diffuser wall. This dynamic capability expands the operating range and surge margin without requiring complex external control mechanisms
Solution Approach 2:
The diffuser vane utilizes the existing rotational axis and structural features of the diffuser assembly to enable its movement. The design leverages the natural geometry of the components, allowing the vane to adjust its position using the available space and structural elements already present in the compressor
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
The relief feature enhances the compressor's performance by increasing its surge margin, leading to improved efficiency and lifespan while maintaining desired cabin pressure, even under varying conditions.
Implementation Method 1
A backing plate with a relief feature in the diffuser assembly of the air compressor allows a portion of the air to bypass the vanes
Data Source
Figure 1~2
Figure 3~5
AI summary
A compressor (16) for pressurizing a flow of air within an aircraft includes an inlet (26) providing the flow of air to the compressor (16). An outlet (28) provides the flow of air, after pressurization by the compressor (16), to a chamber of the aircraft. A diffuser assembly (30) is disposed between the inlet (26) and the outlet (28). The diffuser assembly (30) includes one or more vanes (38) at least partially impeding the flow of air through the diffuser assembly (30). A backing plate (32) is included having a surface (44) adjacent to the one or more vanes (38). The surface (44) includes a relief feature (46) that enables air to bypass the one or more vanes (38). The relief feature (46) has an axial depth (D2) of about 0.25% to 2.5% of a width (D5) of a flow path through the diffuser assembly (30) or of about 0.5% to 5% of a thickness (D4) of a flange (52) of the backing plate (32).