Low-Pressure Compressor Rotor Hub Cavity for Leakage Vortex Control
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Solution Overview
Problem
The existing low-pressure compressors in aircraft turbomachines suffer from efficiency losses due to leakage vortices caused by the clearance between cantilevered blade tips and the rotor hub, which are exacerbated by additional elements like inner shrouds and wipers, leading to increased mass and reduced efficiency.
Innovation Solution
The rotor hub is treated with non-axisymmetric internal recesses and orifices to allow passive circulation of leakage vortices from downstream to upstream, without modifying the stator part, thereby reducing the impact of these vortices on efficiency and mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an inner shroud is added to the rectifier to seal the clearance between blade tips and rotor hub, then leakage vortices are reduced and efficiency is improved, but the mass of the low-pressure compressor increases
Solution Approach 1:
The invention extracts the sealing function from the stator side (inner shroud) and relocates it to the rotor side by creating a cavity in the rotor hub. This removes the need for the inner shroud assembly while maintaining the sealing effect, thereby reducing mass without compromising efficiency.
Solution Approach 2:
The cavity in the rotor hub acts as an intermediary structure that passively manages the leakage vortex flow. By providing a controlled pathway within the rotor hub, the invention mediates the interaction between the blade tips and rotor hub, redirecting leakage flow without requiring additional sealing components.
2Loss of energy
If wipers and abradable coating tracks are added to limit leaks under the inner shroud, then compressor efficiency is improved, but the device complexity and mass increase
Solution Approach 1:
The invention removes the need for wipers and abradable coating tracks by integrating the leak management function directly into the rotor hub cavity structure. This extraction of sealing functions simplifies the overall device complexity while maintaining efficiency.
Solution Approach 2:
The rotor hub cavity is designed to passively manage leakage vortices through its geometric structure alone, without requiring active components or additional sealing mechanisms. The system serves itself by using the natural flow dynamics and cavity geometry to control leakage, eliminating the need for complex auxiliary systems.
3Loss of energy
If the rotor hub is modified with internal recesses and orifices to manage leakage vortices, then efficiency is improved without increasing mass, but the manufacturing complexity increases
Solution Approach 1:
The invention addresses leakage management by creating internal three-dimensional cavities and pathways within the rotor hub, rather than modifying the external blade tip geometry. This dimensional approach allows complex flow control functionality to be integrated into the rotor hub structure without significantly impacting manufacturing processes.
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 approach enhances the efficiency of the low-pressure compressor by minimizing leakage vortices without increasing mass, maintaining aerodynamic performance, and simplifying the compressor architecture.
Implementation Method 1
there is a pressure difference between the intrados and the extrados of the rectifier, and between the trailing and leading edges of the blades, since the pressure of the main air flow within the compressor increases from upstream to downstream
Implementation Method 2
this clearance generally induces a generation and circulation of a so-called 'leakage' air vortex from downstream to upstream
Data Source
Figure 1~2
Figure 3~4A
Figure 4B
AI summary
The invention relates to a sub-assembly (1) for a low-pressure compressor (120) of an aircraft turbine engine (100) comprising a straightener (121) provided with cantilevered vanes (7) and a rotor hub (6) comprising a cavity (2) covered by an inner shroud (3) opposite the vanes (7), orifices (5) being made in this inner shroud (3) to allow an air flow to circulate in the downstream to upstream direction of the low-pressure compressor (120).