Wastewater Pump Impeller With Internal Passage For Blockage Resistance
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Solution Overview
Problem
Existing wastewater pumps face challenges with blockages during partial load operations, where reduced inertial forces from the flow lead to increased blockage issues with fibrous materials and solids.
Innovation Solution
The proposed impeller design features a closed passage extending from the pressure side to the suction side of the blade, creating a disturbance near the leading edge that aids in removing blockages. This passage is optimized in geometry and location to enhance blockage resistance while minimizing impact on hydraulic efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional impellers are used for wastewater conveyance, then the pump operates efficiently at best efficiency point (BEP), but blockage resistance deteriorates during partial load operation when flow rate ratio q*≤0.7
Solution Approach 1:
The blade is segmented into functional zones: a suction side region with enhanced curvature radius for disturbance generation, a pressure side region for jet creation, and a closed passage connecting them. This segmentation allows each region to perform its specific function in combating blockages while maintaining overall hydraulic efficiency.
Solution Approach 2:
The impeller design applies local quality modifications to specific blade regions rather than uniform changes. The suction side curvature radius is increased in the leading edge region (r1) while maintaining different curvature characteristics in other regions (r2, r3). This localized modification targets the blockage-prone areas without compromising overall pump performance.
Solution Approach 3:
The closed passage creates a hydraulic jet that flows from the pressure side to the suction side of the blade. This hydraulic mechanism uses the pressure differential across the blade to generate a disturbance flow that actively removes blockages, particularly effective during partial load operation when inertial forces are reduced.
2Reliability
If impellers create high velocity at suction surface to remove blockage, then blockage resistance improves at BEP, but hydraulic efficiency deteriorates at partial load conditions
Solution Approach 1:
The closed passage is positioned and dimensioned to create disturbance flow before blockages can fully develop and adhere to the blade surface. The suction side curvature modification prepares the flow field in advance to prevent material buildup, particularly in the leading edge region where blockages most commonly occur.
Solution Approach 2:
The impeller design uses the pumped medium itself to create the disturbance jet through the closed passage. The pressure differential across the blade naturally drives the hydraulic jet without requiring additional energy input or external systems, allowing the impeller to self-clean during normal operation.
3Reliability
If closed passage is added to create disturbance jet, then blockage resistance improves, but device complexity increases
Solution Approach 1:
The closed passage is merged with the blade structure itself, using the blade thickness as the passage wall. The passage inlet and outlet are integrated into the pressure and suction sides respectively, eliminating the need for separate components. This merging approach adds the blockage prevention function while minimizing additional structural complexity.
Solution Approach 2:
The closed passage serves multiple functions: it creates the disturbance jet for blockage removal, it acts as a flow communication path between pressure and suction sides, and it modifies the pressure distribution across the blade. This multi-functionality reduces the need for additional separate components to achieve blockage resistance.
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 closed passage effectively prevents blockage build-up at the suction side of the blade, especially during partial load operations, by generating a jet that disturbs material accumulation, thus maintaining pump efficiency and preventing downtime due to clogging.
Implementation Method 1
This jet is driven by the pressure differential between a high pressure region at the pressure side of the blade and the low pressure region inboard of the stagnation line at the suction side of the blade
Implementation Method 2
By the closed passage from the pressure side to the suction side a jet is created using the pumped medium to disturb any material build-up on the suction side
Implementation Method 3
the pressure differential across the closed passage, i.e. the pressure difference between the pressure prevailing at the inlet of the closed passage and the pressure prevailing at the outlet of the closed passage drives the fluid flow through the closed passage, whereas the centrifugal forces will prevent fibers from entering the closed passage
Data Source
AI summary
An impeller for a pump for conveying wastewater is proposed, includes a shroud to be rotated about an axis of rotation defining an axial direction, and a blade to convey the wastewater. The blade includes a leading edge, a trailing edge, a pressure side, a suction side and an upper rim. The blade extends from the shroud in the axial direction to the upper rim and extends in a circumferential direction from the leading edge to the trailing edge. The suction side is the radially inner surface of the blade and the pressure side is the radially outer surface of the blade. The blade includes a closed passage extending inside the blade. The passage has an inlet at the pressure side and an outlet at the suction side of the blade.