Centrifugal Blower Vane for Backflow Suppression
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Solution Overview
Problem
Centrifugal blowers experience backflow and noise due to low-pressure regions, leading to stalling and reduced performance, with existing backflow suppression methods impairing fluid flow and output.
Innovation Solution
A centrifugal blower design featuring a vane on the casing that blocks backflow near the nose section while allowing fluid to exit, with specific edge and height configurations to minimize noise and maintain output flow rate, including angular edges and recessed/protruding parts to manage vortices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a backflow suppression partition is provided in the casing, then backflow is suppressed, but the flow of fluid out from the impeller is impeded, reducing the output flow rate
Solution Approach 1:
The backflow suppression partition is divided into multiple segments (first partition, second partition, third partition) arranged at different angular positions around the impeller. This segmentation allows the partition to block backflow paths while leaving gaps through which fluid can continue to flow outward from the impeller, thus suppressing backflow without completely impeding the output flow rate
Solution Approach 2:
The backflow suppression partition is positioned specifically in the region where backflow occurs (between the start point and end point of the spiral flow passage), rather than blocking the entire flow path. The partition extends only partially in the radial direction, creating a local barrier that addresses the backflow problem while maintaining fluid flow in other regions
2Object-generated harmful factors
If backflow is suppressed near the nose section, then vortex formation is reduced and noise is suppressed, but fluid flow from the impeller may be blocked
Solution Approach 1:
The backflow suppression partition is designed to perform partial backflow suppression rather than complete blockage. By positioning the partition at specific distances from the nose section and extending it only to certain radial heights, the partition achieves sufficient backflow suppression to reduce vortex formation and noise, while maintaining adequate gaps for fluid flow to pass through
Solution Approach 2:
The backflow suppression partition acts as an intermediary structure between the high-pressure region (end point) and low-pressure region (start point) of the spiral flow passage. It provides a controlled barrier that mediates the pressure differential effects, allowing fluid to flow outward from the impeller while preventing reverse flow that would create noise-generating vortices
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
Effectively suppresses noise and maintains output flow rate by blocking backflow and managing vortices, ensuring efficient fluid flow without complete blockage.
Implementation Method 1
an impeller is rotated to cause a fluid to flow in a spiral flow passage formed in a casing, which in turn feeds the fluid under centrifugal force
Implementation Method 2
backflow moving from the start point of the spiral flow passage toward the end point of the spiral flow passage in a region near the nose section of the casing can be blocked by the vane
Implementation Method 3
such backflow forms a vortex, which produces low-frequency sound and thus increases noise
Data Source
AI summary
A centrifugal blower comprises: an impeller (2) provided with blades (12); a casing (3) that houses the impeller (2), surrounds the impeller (2) on an outer side of the impeller (2) in a radial direction of the impeller (2) to form a spiral flow passage (C1) through which air (AR) can flow, and is provided with a nose section (30) forming a start point (S) of the spiral flow passage (C1) and an end point (E) of the spiral flow passage (C1) where one turn of the spiral flow passage (C1) from the start point (S) terminates; a drive unit (4) that rotates the impeller (2) about the center axis (O) of the impeller (2); and a vane (5) that is provided on the bottom plate (22) of the casing (3), divides the spiral flow passage (C1) in the radial direction of the impeller (2), and extends along a circumferential direction of the impeller (2). The rear edge (6) of the vane (5) is located upstream from the nose section (30) in a primary flow direction (DI) of the spiral flow passage (C1).