Impeller Shroud Reinforcing Struts for Cover Rigidity
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Solution Overview
Problem
In rotary machines with closed impellers, the cover experiences low rigidity at its inner peripheral portion, leading to increased vulnerability to centrifugal forces when attempting to increase the rotation rate, which can be mitigated by enhancing the cover's thickness but results in increased weight and centrifugal force influence.
Innovation Solution
The implementation of connection members that connect the disk and cover independently of the blades, positioned closer to the inlet, enhances the rigidity of the cover without increasing its weight, effectively suppressing centrifugal forces by providing additional support and maintaining a straight meridional shape perpendicular to the axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of the cover inner peripheral portion is increased to increase rigidity, then the rigidity is improved, but the weight increases and the influence of centrifugal force increases
Solution Approach 1:
The support structure is segmented into multiple discrete struts distributed around the cover inner peripheral portion, rather than uniformly thickening the entire cover. Each strut provides localized rigid support where needed, while leaving other areas of the cover thin and lightweight.
Solution Approach 2:
The cover is designed with non-uniform thickness distribution - thin in most areas to minimize weight, but with localized thickening at specific positions where struts are attached to provide necessary rigidity support against centrifugal forces.
2Productivity
If the rotation rate of the impeller is increased to improve performance, then the performance is improved, but the centrifugal force acting on the cover increases
Solution Approach 1:
The struts are pre-installed on the cover before the impeller operates at high speeds. These struts are positioned in advance to provide the necessary structural support that will counteract the centrifugal forces that will act on the cover during high-speed rotation, preventing deformation before it occurs.
3Strength
If connection members are added to increase rigidity, then the rigidity is improved, but the device complexity increases
Solution Approach 1:
The struts are integrated with the cover through direct attachment or bonding, merging the support function into the existing cover structure rather than adding completely separate components. This reduces assembly complexity while still providing the necessary rigid support.
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 configuration allows for increased rotation rates while reducing the influence of centrifugal forces on the cover, enhancing its rigidity and preventing pressure loss, thus enabling high-speed operation of the rotary machine.
Implementation Method 1
when an attempt is made to increase the rotation rate of the impeller for the purposed of improving the performance of the rotary machine, there is an increase in centrifugal force acting on the cover of the impeller
Data Source
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AI summary
An impeller includes a disk that has a disk shape centered on an axis, a cover that is disposed to be separated from the disk in an axial direction in which the axis extends, a plurality of blades that connect the disk and the cover to each other and are disposed at intervals in a circumferential direction around the axis, and a connection member that is disposed to be separated from the plurality of blades in the axial direction and connects the disk and the cover to each other. A plurality of the connection members are disposed at intervals in the circumferential direction at positions near an inlet of an impeller flow path with respect to front edges of the blades positioned at positions near the inlet, the impeller flow path being formed between the disk and the cover.