Compressor Inlet Flow Conditioning for Surge Margin
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Turbochargers face instability and reduced surge margin at low compressor speeds, leading to pulsations in air flow and inefficient operation, as existing designs struggle to maintain stable performance across a wide range of engine speeds.
Innovation Solution
The introduction of a perforated flow-conditioning member within the annular gas flow passage of the compressor, featuring axially extending flow conduits that straighten and de-swirl recirculating air, enhancing airflow directionality without affecting total flow, and an annular design that can be removably inserted to improve compressor efficiency and pressure ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional compressor inlet design is used, then the structure is simple, but the surge margin is reduced and stability is poor at low compressor speeds
Solution Approach 1:
The inlet structure is segmented into multiple functional zones: an outer tubular wall forming a gas intake portion, an inner tubular wall defining an inducer portion, and a perforated flow-conditioning member with multiple flow conduits. This segmentation allows independent optimization of each zone to improve surge margin while managing complexity through functional decomposition.
Solution Approach 2:
A perforated flow-conditioning member is introduced as an intermediary component between the outer and inner tubular walls. This mediator straightens and de-swirls recirculating air through its flow conduits, improving airflow directionality and surge margin without requiring complete redesign of the entire inlet structure.
2Use of energy by moving object
If the compressor operates at low speeds, then power consumption is reduced, but airflow instability and pulsations increase
Solution Approach 1:
The flow-conditioning member performs preliminary straightening and de-swirling of recirculating air before it re-enters the compression chamber. This preliminary action prepares the airflow for stable compression even at low speeds, preventing pulsations and maintaining airflow stability without requiring high power consumption.
Solution Approach 2:
The flow conduits in the perforated member change the flow parameters (directionality and swirl) of recirculating air. By modifying these parameters, the system maintains stable airflow characteristics across a broader range of compressor speeds, including low-speed operation where stability would normally deteriorate.
3Productivity
If recirculating air is not conditioned, then the inlet structure is simpler, but airflow directionality is poor and efficiency is reduced
Solution Approach 1:
The flow-conditioning member applies localized flow straightening and de-swirling actions at specific locations where recirculating air passes through its conduits. This local quality improvement enhances overall airflow directionality and compressor efficiency without requiring complex modifications throughout the entire inlet structure.
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
This solution significantly improves the surge margin and maintains efficiency across a broader range of compressor speeds, as demonstrated by improved compressor maps, with minimal impact on overall performance.
Implementation Method 1
a perforated flow-conditioning member within the annular gas flow passage that straightens and de-swirls recirculating air, enhancing airflow directionality
Implementation Method 2
In the case of a centrifugal compressor the outlet passage is in the form of a volute defined by the compressor housing around the impeller wheel
Data Source
AI summary
A compressor for compressing a gas comprises an impeller wheel mounted within a housing (2) defining an inlet and an outlet. The inlet comprises a map-width enhanced structure with an annular flow passage (11) defined between inner (9) and outer (7) tubular walls. The flow passage (11) is in fluid communication with the impeller wheel by virtue of a slot (13) in the inner wall (9). A flow-conditioning member (14) is positioned in the annular flow passage (11) and serves to remove swirl from the gas flow that recirculates through the passage. The flow-conditioning member (14) comprises a body penetrated by a plurality of bores (15). The arrangement provides for a significant improvement in the surge margin of the compressor and is particularly suitable for use in a turbocharger.