Asymmetric Screw Compressor Ports for Pulsation Offset
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Solution Overview
Problem
Multi-rotor screw compressors experience noise and vibration due to rapid fluid flow and pressure pulsations caused by simultaneous opening and closing of compression pockets, which affects efficiency and system components.
Innovation Solution
The compressor design features asymmetric geometry for suction and discharge ports, offsetting the timing of pressure pulsations by varying the size and shape of port portions communicating with compression pairs, ensuring each pocket opens and closes at different times, reducing peak amplitude of pressure pulsations and fluid flow rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If identical geometry ports are used for all compression pairs, then the compressor structure is simple and easy to manufacture, but pressure pulsations and fluid flow surges occur causing noise and vibration
Solution Approach 1:
The patent applies asymmetry by configuring different port geometries for different compression pairs. Specifically, the first compression pair has a first port with a first geometry, while the second compression pair has a second port with a second geometry that differs from the first. This asymmetric design causes compression pockets from different compression pairs to open and close at different times, offsetting pressure pulsations and reducing the peak amplitudes of fluid flow surges, thereby reducing noise and vibration while maintaining manufacturing feasibility
Solution Approach 2:
The patent applies local quality by making each port's geometry specific to its associated compression pair. The first port portion communicating with the first compression pair has geometry optimized for that pair's operating characteristics, while the second port portion communicating with the second compression pair has different geometry tailored to its characteristics. This localized optimization allows each compression pair to operate with reduced pressure pulsations while maintaining overall system simplicity
2Device complexity
If identical geometry ports are used for all compression pairs, then the compressor structure is simple, but fluid flow rates surge causing pressure pulsations that affect system efficiency
Solution Approach 1:
The patent uses asymmetric port geometries where the first port and second port have different configurations tailored to their respective compression pairs. This asymmetry staggers the opening and closing times of compression pockets across different compression pairs, preventing simultaneous fluid flow surges. The result is reduced peak pressure pulsations and more uniform fluid flow rates, improving compressor efficiency while avoiding excessive structural complexity
Solution Approach 2:
The patent changes the geometric parameters of the ports for different compression pairs. By varying parameters such as port area, shape, or position between the first port and second port, the patent modifies the timing characteristics of compression pocket opening and closing. This parameter variation offsets pressure pulsations and smooths fluid flow rates, enhancing productivity without requiring complex overall device architecture
Data Source
AI summary
A multi-rotor screw compressor includes a housing, a sun rotor, and first and second planet rotors. The first planet rotor intermeshes with the sun rotor to define a first compression pair. The second planet rotor intermeshes with the sun rotor to define a second compression pair. The first and second compression pairs are rotatably mounted in the housing. The housing includes a first port, a portion of which is in communication with the first compression pair, and a second port, a portion of which is in communication with the second compression pair. The portions of the first and second ports which communicate with the first and second compression pairs have a different geometry for offsetting pulsations in a working fluid flowing through the ports.