Propeller Nozzle Edge Flow Control
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Solution Overview
Problem
Propeller nozzles experience significant power losses due to turbulence in the edge flow around the propeller blade end regions, leading to reduced performance.
Innovation Solution
The implementation of flow directing means that divert a portion of the peripheral flow away from the gap between the propeller blade end areas and the inner wall of the nozzle onto the propeller face, reducing vortex formation and turbulence by directing edge flow onto the propeller surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the gap between propeller blade end areas and the inner wall of the nozzle is reduced to minimize circulation losses, then power efficiency is improved, but the risk of collision due to vibrations increases
Solution Approach 1:
The propeller blade end areas are given a spherical outer surface that corresponds to a spherical zone on the inner wall of the nozzle. This curved geometry allows the blades to maintain a consistent spherical gap from the nozzle wall while rotating, reducing circulation losses without increasing collision risk. The spherical configuration naturally accommodates vibrational movements while preserving the optimized gap distance.
2Loss of energy
If flow directing means are added to divert edge flow onto the propeller surface, then circulation losses are reduced, but device complexity increases
Solution Approach 1:
The flow directing means are integrated directly into the inner wall of the nozzle, merging the flow control function with the existing nozzle structure. This eliminates the need for separate, additional components and reduces overall device complexity while still achieving the goal of diverting edge flow onto the propeller surface to reduce circulation losses.
Solution Approach 2:
The flow directing means act as an intermediary element between the edge flow and the propeller surface, redirecting the flow path without requiring direct mechanical connection to the rotating propeller. This intermediary structure achieves flow control while maintaining simplicity and avoiding complex moving parts.
3Power
If the nozzle is designed with a tapered conical shape to increase thrust, then propulsion efficiency is improved, but the gap between propeller blades and nozzle wall becomes non-uniform
Solution Approach 1:
By using spherical surfaces for both the propeller blade end areas and the corresponding zone on the nozzle inner wall, the design accommodates the tapered conical shape of the nozzle while maintaining a uniform spherical gap. The curvature of the spherical surfaces allows the gap to remain consistent despite the changing radial distance caused by the conical taper, thus preserving both propulsion efficiency and gap uniformity.
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 approach minimizes the flow rate through the gap, thereby reducing circulation losses and enhancing the overall performance of the propeller nozzle while maintaining the required minimum gap dimensions.
Implementation Method 1
flow directing means that divert a portion of the peripheral flow away from the gap between the propeller blade end areas and the inner wall of the nozzle onto the propeller face
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
The propeller nozzle (100) has a nozzle (10) and a propeller (20) with multiple propeller blades (22). A flow guiding unit is provided for directing a portion of the flow edge on the propeller surface, and is arranged in the immediate vicinity of a gap, particularly in the direction of flow in front of the gap. The flow guiding unit is formed circumferentially in the circumferential direction of the nozzle, and has a recovery in the inner wall of the nozzle. The recovery is formed as depression (15) in the inner wall of the nozzle.