Compressor Diffuser Plasma Actuators Stall Margin
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Solution Overview
Problem
Centrifugal compressors in gas turbine engines face reduced mass flow rates and stall due to flow separation in diffuser pipe assemblies, which existing designs struggle to prevent effectively.
Innovation Solution
Incorporation of plasma actuators adjacent to the walls of the diffuser pipes, connected to a source of electricity and configured to generate electric fields between electrodes, ionizing air particles and accelerating sub-flows in boundary layer regions to prevent stall.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If plasma actuators are installed in the diffuser pipes, then stall margin is improved and flow separation is prevented, but device complexity increases
Solution Approach 1:
The patent replaces traditional mechanical flow control devices (such as variable geometry diffusers or active flow control mechanisms) with plasma actuators that use electrohydrodynamic forces to control boundary layer separation. The plasma actuators generate ionized gas flows that interact with the boundary layer to prevent separation, eliminating the need for moving mechanical parts while improving stall margin.
Solution Approach 2:
The patent changes the physical state of the gas in the boundary layer by ionizing it through plasma discharge. This parameter change (from neutral gas to ionized plasma) enables the generation of body forces that actively control the boundary layer, preventing flow separation and delaying stall without requiring mechanical intervention.
2Productivity
If plasma actuators are used to prevent flow separation, then mass flow rate is improved, but use of energy increases
Solution Approach 1:
The patent applies plasma actuation selectively in specific regions of the diffuser where flow separation is most likely to occur, rather than throughout the entire diffuser passage. This partial action approach maintains mass flow rate by targeting critical separation zones while minimizing the total energy consumption of the plasma actuators.
Solution Approach 2:
The plasma actuators can be operated in a periodic or pulsed manner rather than continuously, activating them only when flow separation is detected or anticipated. This periodic action maintains effective flow control and mass flow rate while significantly reducing average energy consumption compared to continuous operation.
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 plasma actuators effectively delay surge and enhance stall margin by re-energizing flow fields and preventing boundary layer separation, improving compressor efficiency and performance.
Implementation Method 1
generating electric fields in boundary layer regions in vicinity of walls bounding the flow passages and at locations closer to the impeller than to outlets of the flow passage thereby ionizing particles of air in the boundary layer regions for accelerating the sub-flows
Implementation Method 2
plasma actuators operable to generate an electric field through the dielectric layer
Implementation Method 3
plasma actuators positioned adjacent the walls and operatively connectable to a source of electricity
Data Source
AI summary
There is disclosed a centrifugal compressor including an impeller rotatable about an axis and a diffuser downstream of the impeller. The diffuser has walls delimiting flow passages. Plasma actuators are positioned adjacent the walls and are operatively connectable to a source of electricity. The plasma actuators have a first electrode, a second electrode, and a dielectric layer therebetween. The first electrode is upstream of the second electrode. The first electrode is exposed to the flow passage. The second electrode is shielded from the flow passage by the dielectric layer. The plasma actuators are operable to generate an electric field through the dielectric layer. The plasma actuators are located closer to inlets of the flow passage than to outlets of the flow passages. A method of operating the compressor is disclosed.