Impeller Draft Angle Variation for Pump Efficiency
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Solution Overview
Problem
Existing fluid pumps with impellers having a plurality of blades suffer from decreased pumping efficiency due to the widening distance between adjacent blades from the center of the impeller, leading to diverging flow streams and reduced momentum transfer.
Innovation Solution
The impeller design features a hub with a larger draft angle for manufacturing ease, while the blades have a varying draft angle along their radial length, with a significantly reduced draft angle near the outer ring to enhance fuel momentum transfer and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a constant draft angle is maintained along the radial length of each blade for manufacturing ease, then the impeller can be easily extracted from molds, but the distance between adjacent blades widens from inboard to outboard causing flow stream divergence and decreased pumping efficiency
Solution Approach 1:
The patent applies local quality by varying the draft angle along the radial length of the blades. Specifically, the draft angle is larger near the inboard end (hub region) to facilitate mold extraction, and progressively smaller toward the outboard end (outer ring region) to maintain consistent blade spacing and prevent flow divergence. This localized variation in geometric parameter resolves the contradiction between manufacturing ease and pumping efficiency.
Solution Approach 2:
The patent implements parameter changes by transitioning the draft angle from a constant value to a variable parameter that changes along the radial direction. The draft angle is designed to decrease from the inboard end to the outboard end of the blades, transforming the geometric parameter to simultaneously satisfy both mold extraction requirements and flow efficiency requirements at different radial positions.
2Ease of manufacture
If a larger draft angle is used throughout the blade length, then mold extraction is facilitated with minimal friction, but the flow stream exiting the blade diverges leading to reduced momentum transfer
Solution Approach 1:
The patent applies local quality by differentiating the draft angle requirements at different locations along the blade. The inboard end maintains a larger draft angle for mold extraction, while the outboard end uses a smaller draft angle to preserve flow coherence and momentum transfer, thus locally optimizing each region for its specific function.
Solution Approach 2:
The patent segments the blade into different radial zones with different draft angle characteristics. The inboard region (near the hub) has a larger draft angle optimized for manufacturing, while the outboard region (near the outer ring) has a smaller draft angle optimized for fluid dynamics performance, effectively dividing the blade into functional segments.
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 design increases pumping efficiency by promoting high momentum transfer of the fluid, achieving 51.2% efficiency compared to 48.4% for a similar pump without this impeller design, resulting in a 5.8% efficiency improvement.
Implementation Method 1
centrifugal forces causes the fuel to exit the blade on the outboard half of the of the blade radial length
Data Source
Figure 1
Figure 2
Figure 3A~5B
AI summary
An impeller for a fluid pump includes a hub having an outer surface; an outer ring which is concentric with the hub and having an inner surface; and a plurality of blades extending from a root at the outer surface to a tip at the inner surface. Each of the blades has a first leg and a second leg which meet at a vertex such that a concave side of the blades faces toward a rotational direction and such that a convex side of the blades faces away from the rotational direction. The concave side of each one of the plurality of blades forms a draft angle with the convex side of another one of the plurality of blades which is immediately adjacent thereto in the rotational direction. The draft angle at the inner surface is less than or equal to 10% of the draft angle at the outer surface.