Centrifugal Compressor Recirculation Passage with Axial Ring Control
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Solution Overview
Problem
Centrifugal compressors face instability and reduced efficiency due to the recirculation passage, which causes undesirable backflow and flow instability at lower loads, and inefficiency at higher loads.
Innovation Solution
A centrifugal compressor design featuring a housing with a movable ring and controller that adjusts the recirculation passage by obstructing openings, allowing for variable recirculation control through rotatable inlet guide vanes, optimizing operation between surge conditions and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a recirculation passage is provided in a centrifugal compressor, then stability is improved and surge conditions are reduced at lower loads, but efficiency deteriorates at higher loads due to flow leakage
Solution Approach 1:
The recirculation passage is designed with movable inlet and outlet openings that can dynamically adjust their positions along the axial direction. The inlet opening moves axially to control recirculation flow at different operating conditions, allowing the system to optimize between stability at low loads and efficiency at high loads by adapting the recirculation passage configuration in real-time
2Stability of the object's composition
If the recirculation passage is kept open to maintain stability at partial loads, then compressor stability is improved, but efficiency deteriorates due to continuous recirculation flow
Solution Approach 1:
The inlet opening of the recirculation passage is configured to move axially between different positions. At partial loads, the inlet opening is positioned to allow recirculation flow for stability. At high loads, the inlet opening moves to a position that restricts or closes the recirculation passage, eliminating the efficiency penalty from continuous recirculation while maintaining system stability
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 design enhances stability and minimizes surge conditions at partial loads while maintaining efficiency at higher loads by dynamically controlling the recirculation passage, avoiding the efficiency penalties associated with traditional ported shrouds.
Implementation Method 1
an impeller that rotates about an axis to draw fluid into the compressor and compress the fluid to an outlet. The fluid is directed radially outward from the axis through a diffuser passage that increases a pressure of the fluid
Implementation Method 2
Some centrifugal compressors include a ported shroud that surrounds an inlet area of the compressor for providing a recirculation passage. This helps to move the surge line and provide stability at lower load conditions.
Implementation Method 3
A plurality of inlet guide vanes are rotatable and situated in the inlet chamber
Data Source
AI summary
An example centrifugal compressor includes a housing that defines an inlet chamber and includes first and second openings that define a recirculation passage in fluid communication with the inlet chamber. An impeller is disposed within the housing and is rotatable about a longitudinal axis to draw fluid into the inlet chamber. The first and second openings are at different axial locations along the longitudinal axis. A plurality of inlet guide vanes are rotatable and situated in the inlet chamber. The centrifugal compressor includes a ring and a controller for moving the ring along the longitudinal axis between a first position and a second position when rotating the inlet guide vanes. The ring obstructs at least one of the first and second openings more in the second position than in the first position.