Centrifugal Compressor Surge Control via Recirculation Vanes
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Solution Overview
Problem
Centrifugal compressors in turbocharger applications experience compressor surge, leading to performance loss and potential engine damage, due to flow oscillations and instability, which existing technologies fail to adequately prevent or control.
Innovation Solution
A centrifugal compressor with a fluid recirculation system that includes a bleed port and recirculation flow channel with highly cambered vanes to alter the swirl of the compressed fluid, injecting it back into the inlet with a substantial axial velocity component, thereby influencing a wide area of the compressor blades to reduce surge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a recirculation system with bleed port and cambered vanes is added to control surge, then compressor surge is reduced and operating range is expanded, but device complexity increases
Solution Approach 1:
The recirculation system is segmented into distinct functional components: a bleed port for extracting fluid, a recirculation flow channel for guiding flow, and highly cambered vanes for altering swirl. This segmentation allows each component to be optimized independently while working together to control surge, resolving the contradiction by making the complex system modular and manageable.
Solution Approach 2:
The recirculation system acts as an intermediary mechanism between the compressor wheel and the inlet, intercepting compressed fluid and redirecting it with modified flow characteristics. This intermediary function allows surge control without directly modifying the compressor wheel or inlet structure, managing the complexity through a dedicated control system.
2Stability of the object's composition
If highly cambered vanes are used to alter swirl of bleed portion, then flow distribution is improved and surge is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The vanes are designed with highly cambered geometry, representing a significant change in the shape parameter compared to conventional straight or lightly curved vanes. This parameter change enables effective swirl alteration and flow redistribution to control surge, while the design accepts increased manufacturing precision requirements as a trade-off for achieving the desired flow stability.
3Productivity
If bleed port is positioned intermediate leading and trailing edges of blades, then effective flow interception is achieved, but structural complexity of compressor housing increases
Solution Approach 1:
The bleed port is positioned at a specific location intermediate the leading and trailing edges of the compressor blades, where the flow characteristics are optimal for interception. This localized placement provides effective surge control by targeting the specific region where flow redistribution is most beneficial, while minimizing the overall structural complexity by limiting modifications to a specific area of the housing.
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 recirculation system effectively reduces compressor surge, expanding the operating range and preventing performance losses by redistributing the flow field and minimizing losses through gradual flow direction changes and reduced separation.
Implementation Method 1
A plurality of highly cambered vanes are disposed in the recirculation flow channel and are configured to alter a degree of swirl in the bleed portion prior to the bleed portion being discharged through the discharge end
Implementation Method 2
A bleed port is defined in the inner surface of the compressor housing at a location intermediate the leading and trailing edges of the blades, for bleeding off a bleed portion of the fluid being compressed by the compressor wheel
Implementation Method 3
The recirculation flow channel has a discharge end that is positioned to discharge the bleed portion into the inlet duct
Data Source
AI summary
A centrifugal compressor for compressing a fluid comprises a compressor wheel having a plurality of circumferentially spaced blades, and a compressor housing in which the compressor wheel is mounted. The compressor housing includes an inlet duct through which the fluid enters in an axial direction and is led by the inlet duct into the compressor wheel, and an inner surface located radially adjacent the tips of the blades. A bleed port is defined in the inner surface of the compressor housing at a location intermediate the leading and trailing edges of the blades, for bleeding off a bleed portion of the fluid, the bleed port leading to a recirculation flow channel that feeds the bleed portion back into the inlet duct. Highly cambered vanes are disposed in the recirculation flow channel for turning the bleed portion to take out and in some cases reverse the swirl in the bleed portion.