Adjustable-Trim Centrifugal Compressor With Divergent-Wall Diffuser
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing turbochargers face challenges in expanding the surge-free operation range of centrifugal compressors to lower flow rates, particularly at high load or torque and low engine speed, or when exhaust gas recirculation occurs, leading to flow instability and surge.
Innovation Solution
Incorporating a centrifugal compressor with a divergent-wall diffuser and an adjustable inlet-adjustment mechanism that adjusts the effective inlet diameter, allowing the surge line to be shifted to lower flow rates by reducing the inlet diameter and enhancing diffuser performance through divergent-wall geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the effective inlet diameter of the centrifugal compressor is reduced to delay surge to lower flow rates, then the surge-free operation range is expanded to lower flow rates, but the high-flow performance is degraded
Solution Approach 1:
The patent employs an adjustable inlet-adjustment mechanism that can dynamically change the effective inlet diameter of the centrifugal compressor based on operating conditions. This dynamic adjustment allows the system to optimize performance across different flow rates, expanding the surge-free operation range at low flow rates while maintaining high-flow performance when the mechanism is positioned to provide a larger effective inlet diameter.
Solution Approach 2:
The patent changes the effective inlet diameter parameter of the centrifugal compressor using an adjustable mechanism. By varying this geometric parameter, the system can shift the surge line to lower flow rates when needed, while the ability to adjust the parameter allows maintenance of optimal high-flow performance when operating conditions require it.
2Ease of manufacture
If the diffuser walls are made parallel to simplify manufacturing, then the manufacturing complexity is reduced, but the diffusion rate and compressor performance are degraded
Solution Approach 1:
The patent applies divergent-wall geometry to the diffuser, where the wall angle varies locally along the radial direction. This local variation in geometry optimizes the diffusion rate and compressor performance without requiring complex manufacturing throughout the entire diffuser structure, as the divergent-wall design can be implemented through standard machining processes.
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 combination of the divergent-wall diffuser and adjustable inlet mechanism significantly delays surge, stabilizing compressor operation at lower flow rates and maintaining high-flow performance by reducing blade incidence angles and increasing diffusion rate.
Implementation Method 1
the diffuser receiving the compressed air from the compressor wheel and diffusing the compressed air and delivering the diffused compressed air into the volute
Implementation Method 2
along at least a portion of a radial length of the diffuser the first and second walls diverge from each other in a radially outward direction
Implementation Method 3
the inlet-adjustment mechanism in the closed position forming an orifice of reduced diameter relative to a nominal diameter of the inlet... significantly delays surge, stabilizing compressor operation at lower flow rates and maintaining high-flow performance by reducing blade incidence angles
Implementation Method 4
a compressor wheel mounted in the compressor housing and connected to the rotatable shaft for rotation therewith, the compressor wheel having blades and defining an inducer portion and an exducer portion
Implementation Method 5
a turbine wheel mounted on the other end of the shaft in a turbine housing... The exhaust gas flows from the chamber through the nozzle to the turbine wheel and the turbine wheel is driven by the exhaust gas. The turbine thus extracts power from the exhaust gas
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A centrifugal compressor for a turbocharger includes an inlet-adjustment mechanism in an air inlet for the compressor, operable to move between an open position and a closed position in the air inlet. Movement of the inlet-adjustment mechanism from the open position to the closed position is effective to shift the compressor's surge line to lower flow rates. The compressor includes a diffuser extending between an exducer of the compressor wheel and a volute for collecting pressurized air from the compressor. The diffuser is defined between first and second walls that diverge from each other in a radially outwardly direction through the diffuser. The divergent-wall diffuser enhances the shift of the surge line to lower flow rates when the inlet-adjustment mechanism is put in the closed position.