Radial Compressor Diaphragm Passive Flow Control
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Solution Overview
Problem
Centrifugal compressors experience aerodynamic instabilities and surge phenomena at low flow rates, limiting their operating range and requiring costly and complex solutions like variable-pitch vanes and anti-surge protection devices, which are prone to malfunctions.
Innovation Solution
Incorporating a diaphragm with radially inclined passages between the suction and discharge zones of the compressor stage to create an artificial gas recirculation, increasing the flow rate and maintaining stability without additional control devices or measurement instrumentation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If variable-pitch blades or movable walls are used in the diffuser, then aerodynamic stability at low flow rates is improved, but device complexity and manufacturing cost increase due to mechanical devices, drilling, and sealing requirements
Solution Approach 1:
The diffuser is segmented into multiple passages separated by diaphragms with inclined passages. This segmentation allows passive flow control in each passage independently, improving aerodynamic stability without requiring complex mechanical devices for the entire diffuser.
Solution Approach 2:
The inclined passages in the diaphragms automatically redirect flow and prevent separation phenomena without requiring external control systems. The structure itself provides the flow control function, eliminating the need for variable-pitch blades or movable walls.
2Stability of the object's composition
If anti-pumping protection devices with gas recirculation are used, then compressor stability is improved, but device complexity and cost increase due to instrumentation and control valves
Solution Approach 1:
The inclined passages in the diaphragms automatically prevent pumping phenomena and ensure compressor stability without requiring flow rate measurement instrumentation or control valves. The passive geometric structure performs the protection function inherently.
Solution Approach 2:
The complex anti-pumping protection system with instrumentation and control devices is extracted and replaced by simple inclined passages integrated into the diaphragm structure, maintaining stability while eliminating unnecessary complexity.
3Productivity
If the compressor operates below the stability range, then productivity is improved, but aerodynamic instabilities and pumping phenomena occur
Solution Approach 1:
The flow path is divided into multiple passages with inclined diaphragms, allowing stable operation at low flow rates by preventing flow separation in each passage. This enables the compressor to operate below the traditional stability range without instabilities.
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 diaphragm effectively eliminates aerodynamic instabilities and pumping phenomena at low flow rates, allowing operation within the stability range and extending the compressor's operational range without leaks or environmental impact, applicable to all pressure levels and types of gases.
Implementation Method 1
The passages are arranged in the thickness of the diaphragm 4 so as to extend at an inclined angle radially outwards between a zone converging towards the rotor 3, on the suction side, and a radial zone, located in the diffuser, downstream of the wheel 2
Data Source
Figure 1~2
Figure 3~4
AI summary
The diaphragm (4) has a set of passages (9) extending between two mutually opposite faces of the diaphragm, so as to create a flow of gas between the opposite faces depending on a pressure difference prevailing on either side of the diaphragm. The set of passages is arranged regularly in the diaphragm, where each passage extends, on one of the faces of the diaphragm, between two fixed blades provided on the diaphragm, and the number of passages corresponds to the number of fixed blades of the diaphragm. An independent claim is also included for a compression stage of a compressor.