Multiblade Fan Flow Regulating Block for Air Reentry
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Solution Overview
Problem
Multiblade fans experience degradation in air-sending performance due to air flow reentering the fan casing through the space between the tongue and impeller, causing pressure loss and interference with the impeller, especially under high static pressure conditions.
Innovation Solution
A flow regulating block is introduced to guide reentering air flow into a space between the block and the circumferential wall, preventing interference with the impeller and reducing pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wall protrusions are added to the duct connected to the tongue to prevent air flow reentering the fan casing, then air reentry is reduced, but pressure loss increases and air-sending performance degrades
Solution Approach 1:
The invention extracts the flow regulation function from the duct wall protrusions and relocates it to a dedicated flow regulating block positioned at the duct inflow port. This separation allows the protrusions to be removed while maintaining flow control through the block, eliminating pressure loss from wall interference while preventing air reentry through the block's flow regulation mechanism
Solution Approach 2:
The flow regulating block acts as an intermediary component between the duct and the fan casing interior. It mediates the air flow by guiding it smoothly into the fan casing through a dedicated flow regulation surface, preventing direct reentry while avoiding the pressure loss associated with wall protrusions
2Reliability
If wall protrusions are added to prevent air flow reentering the fan casing, then air reentry is reduced, but air-sending performance degrades due to interference with high-velocity air flow
Solution Approach 1:
The invention removes the wall protrusions from the duct and extracts the flow control function to a separate flow regulating block at the inflow port. This eliminates interference with the high-velocity air flow in the duct while maintaining prevention of air reentry through the block's positioning and flow regulation surface
Solution Approach 2:
The flow regulating block performs preliminary flow regulation at the duct inflow port before air enters the fan casing. By pre-guiding the air flow in the correct direction at the inflow port, it prevents reentry without interfering with the high-velocity main flow in the duct
3Productivity
If a flow regulating block is added to guide reentering air flow, then air-sending performance is improved, but device complexity increases
Solution Approach 1:
The flow regulating block performs multiple functions simultaneously: it guides air flow into the fan casing, prevents air reentry through its positioning and flow regulation surface, and reduces turbulence. This multi-functionality justifies the added component by consolidating several flow control tasks into a single element
Solution Approach 2:
The flow regulating block is positioned specifically at the duct inflow port where flow regulation is most critical. Its presence is localized only where needed to guide air into the fan casing, rather than requiring complex structures throughout the entire duct system
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 solution enhances air-sending performance by minimizing pressure loss and noise levels, allowing the multiblade fan to maintain intended air flow rates under high static pressure conditions without reducing flow rate or increasing noise.
Implementation Method 1
pressurizes air taken through an inlet and discharges the pressurized air through an outlet by using a centrifugal force applied to the air through an impeller rotating in a fan casing
Data Source
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AI summary
A multiblade fan includes an impeller including a rotating plate and blades and further includes a fan casing having a circumferential wall facing a periphery of the impeller and a first end face disposed adjacent to distal ends of the blades. The circumferential wall extends at an increasing distance from a rotary shaft in a rotation direction of the impeller. The first end face has an inlet. The multiblade fan further includes a duct having an outlet through which air from the fan casing is discharged and a flow regulating block disposed on an inner surface of the first end face. The flow regulating block regulates a flow of the air. The duct includes a diffuser plate extending from an upstream end of the circumferential wall in an air flow direction. The diffuser plate extends in the rotation direction outwardly in a radial direction of the impeller. The circumferential wall includes a tongue that is bent part of the upstream end. The tongue is connected to the diffuser plate. The first end face has a bell mouth provided at the inlet and protruding into the fan casing. The flow regulating block is spaced from the circumferential wall and extends along the bell mouth in the rotation direction such that the flow regulating block is located in a range of 120 degrees from a reference position on a line connecting the rotary shaft to a tip of the tongue.