Centrifugal Compressor Resistive Element Surging Limit
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Solution Overview
Problem
Centrifugal compressors in exhaust turbochargers face limitations in operating range due to surging and choking issues, with existing solutions like casing treatments and variable diffusers requiring complex drive mechanisms and incurring additional costs without substantial improvements.
Innovation Solution
Incorporating a resistive element that narrows the radial passage cross-section of the air intake passage between the impeller wheel and the air intake opening, increasing inflow velocity to the blade by biasing intake air to the hub or shroud side, thereby reducing surging and maintaining performance at low flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a variable diffuser with rotating and sliding vanes is applied to expand the operating range, then the operating range is significantly expanded, but the device complexity increases and reliability decreases due to sliding parts and gas leakage
Solution Approach 1:
The invention extracts and eliminates the complex drive mechanism and sliding parts from the variable diffuser system. Instead of using rotating vanes with motors and linkages, the patent employs a stationary diffuser with strategically positioned openings that passively guide airflow. This removes the problematic sliding parts and gas leakage issues while maintaining the ability to control airflow distribution across different operating conditions.
Solution Approach 2:
The invention introduces a stationary diffuser structure with controlled openings as an intermediary element between the impeller and outlet. This mediator passively regulates airflow distribution using the pressure differential created during compression, eliminating the need for active mechanical control systems while achieving variable geometry effects.
2Adaptability or versatility
If a flow rate adjusting valve is provided in the diffuser part to expand the operating range, then the operating range improves, but the device complexity and cost increase due to the drive mechanism
Solution Approach 1:
The stationary diffuser structure with controlled openings automatically adjusts airflow distribution based on the pressure differential generated during compression. The system self-regulates without external control mechanisms, using the inherent physics of fluid flow to adapt to different operating conditions. This eliminates valves and their drive mechanisms entirely.
3Adaptability or versatility
If casing treatment with grooves and circulation passages is applied, then the operating range is enlarged, but substantial improvement cannot be expected
Solution Approach 1:
The invention applies local quality control by positioning specific openings at strategic locations within the stationary diffuser. Rather than using general circulation passages throughout the casing, the patent creates localized flow control zones that precisely manage airflow distribution where it is most needed, achieving substantial performance improvement with simpler structures.
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 resistive element effectively decreases the surging limit flow rate at low flow rates by enhancing inflow velocity to the impeller wheel, suppressing stall, and maintaining compressor performance without the need for complex drive mechanisms or significant cost increases.
Implementation Method 1
A resistive element against an air intake flow is provided in either an inner peripheral wall side portion or a center side portion of the air intake passage, so that, at a low flow rate time, a cross-sectional area of the air intake passage is narrowed by the resistive element thereby increasing an inflow velocity to a blade of the impeller wheel
Implementation Method 2
a centrifugal compressor which compresses an intake air by an impeller wheel rotating by a rotary shaft
Data Source
AI summary
An object of the present invention is to decrease a surging limit flow rate at a low flow rate time, by increasing the inflow velocity to the blade of the impeller wheel, by providing a resistive element that narrows in the radial direction a passage cross section of an air intake passage which communicates between a impeller wheel of a centrifugal compressor and an air intake opening.The centrifugal compressor includes: the compressor housing 9 having the air intake opening 13 opened in a rotary shaft direction, and the air intake passage 11; and the impeller wheel 7 for compressing the air flowing in from the air intake opening 13, inside the housing. The resistive elements 27 and 43 against the air intake flow are provided in either the inner peripheral wall 23 side portion or the center side portion of the air intake passage 11, so that, at the low flow rate time, a cross-sectional area of the air intake passage 11 is narrowed by the resistive elements 27 and 43 thereby increasing the inflow velocity to the blade 19 of the impeller wheel, and the intake air flow is biased to the hub side of the blade 19, and the intake air flow is biased to flow to the hub side or the shroud side of the blade 19.