Centrifugal Compressor Impeller Cooling via Annular Sheet
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Solution Overview
Problem
The impeller of a centrifugal compressor in turbomachines experiences significant heat absorption due to viscous shear with the diffuser flange, leading to increased temperature and reduced lifespan, and existing thermal protection solutions are heavy and increase the turbomachine's mass and inertia.
Innovation Solution
An annular sheet is fixed to the diffuser flange, creating separate air passages to redirect heat away from the impeller through convection, with radial fins for structural support and to ensure force transmission without deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an annular thermal protection shield is fixed on the impeller to protect it from heat, then the impeller is protected from heat degradation, but the shield increases the mass of the turbomachine and the inertia of the impeller
Solution Approach 1:
An annular sheet is introduced as an intermediary element between the diffuser flange and the impeller. This sheet creates a cooling passage that allows air to flow and absorb heat away from the impeller, protecting it without requiring a heavy thermal shield to be attached to the impeller itself.
Solution Approach 2:
The invention uses air flow through the cooling passage to remove heat from the impeller. Air is introduced into the space between the annular sheet and the impeller, where it absorbs heat through convection and carries it away, providing thermal protection through pneumatic means rather than heavy thermal insulation.
2Reliability
If an annular thermal protection shield is fixed on the impeller to protect it from heat, then the impeller is protected from heat degradation, but the shield increases the inertia of the impeller
Solution Approach 1:
The annular sheet acts as a mediator that enables active cooling of the impeller by creating a passage for air flow. This continuous cooling process removes heat that would otherwise accumulate and degrade the impeller, extending its service life without the need for heavy protective shielding.
Solution Approach 2:
The cooling system operates continuously as air flows constantly through the passage between the annular sheet and the impeller. This continuous heat removal process ensures the impeller remains at acceptable temperatures throughout operation, maintaining its service life and performance.
3Strength
If the diffuser flange is made robust to ensure force transmission, then structural integrity is maintained, but the mass of the turbomachine increases
Solution Approach 1:
Instead of increasing the mass or thickness of the diffuser flange to improve its mechanical properties, the invention adds radial fins that extend in a new dimension perpendicular to the flange surface. These fins increase the moment of inertia and structural rigidity without significantly increasing the overall mass of the assembly.
Solution Approach 2:
The annular sheet is a thin, lightweight component that is fixed to the diffuser flange. It provides the necessary structural function of creating the cooling passage while adding minimal mass. The sheet works in conjunction with the flange and fins to achieve both structural integrity and thermal management.
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 solution effectively reduces heat absorption by the impeller, thereby increasing its service life without adding significant mass or inertia to the turbomachine.
Implementation Method 1
The heat generated by the shearing of the air which flows in the first annular passage is absorbed for the most part by convection by the air leaving the diffuser and flowing in the second annular passage
Implementation Method 2
This air is subjected to significant viscous shear between the impeller and the flange of the diffuser, which generates a large amount of heat absorbed largely by the impeller of the compressor
Data Source
Figure 1~3
Figure 2
AI summary
Cooling system for the impeller of a centrifugal compressor in a turbomachine, this compressor (10) supplying an annular diffuser (12) having a flange (26) which extends downstream and along the impeller of the compressor and which is covered on the upstream side by an annular plate (90) which delimits, with the impeller of the compressor, a first annular passage (39) of air flow taken from the outlet of the compressor and, with the flange of the diffuser, a second annular passage (98) of flow of part of the air flow exiting the diffuser.