Marine Propeller Noise Reduction via Fuzzy Logic Optimization
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Solution Overview
Problem
Current propeller noise prediction methods are complex and require repetitive modeling for design parameter variations, and there is a need to optimize design parameters like pitch angle and number of blades to reduce noise levels for enhanced stealth technology.
Innovation Solution
A propeller design with a diameter of 360-400 mm, featuring 6 blades and a +5-degree pitch angle, optimized using fuzzy logic and computational fluid dynamics to minimize noise while maintaining required thrust and torque, along with a fuzzy logic model for predicting propeller noise across various parameter combinations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If computational methods are used to predict propeller noise with given geometry, then noise prediction is achieved, but the entire process of modeling and solving must be repeated for every variation in design parameters
Solution Approach 1:
The patent pre-establishes multiple propeller models with different design parameters (number of blades, pitch angle, skew angle) before actual noise prediction is needed. When a specific configuration is required, the pre-modeled data can be directly utilized or interpolated, eliminating the need to repeat the entire modeling and solving process for every design variation.
Solution Approach 2:
The patent creates multiple copies of propeller models with varying parameters (5-blade, 6-blade, 7-blade configurations with different pitch and skew angles). These pre-computed models serve as templates that can be referenced or interpolated to quickly obtain noise predictions for specific design requirements without重新进行完整的建模和求解.
2Force
If the number of blades and pitch angle are increased to optimize thrust, then thrust performance is improved, but propeller noise increases
Solution Approach 1:
The patent optimizes specific local parameters of the propeller blades, including the distribution of pitch angle along the blade span, skew angle variations, and blade cross-sectional shapes. By carefully adjusting these local characteristics rather than simply increasing the number of blades or overall pitch, the design achieves adequate thrust while minimizing noise generation through optimized local flow conditions.
Solution Approach 2:
The patent systematically varies multiple design parameters (number of blades from 5-7, pitch angles from +5 to +15 degrees, skew angles from 15 to 30 degrees) to find the optimal combination. The analysis reveals that moderate pitch angles combined with appropriate skew angles can maintain thrust performance while significantly reducing noise compared to high-pitch configurations.
3Object-generated harmful factors
If multiple design parameters are varied to reduce noise, then noise levels decrease, but the complexity of design optimization increases
Solution Approach 1:
The patent segments the optimization process into distinct phases: first establishing baseline models with different blade counts, then systematically varying pitch and skew angles for each configuration. This segmented approach allows the complex multi-parameter optimization to be broken down into manageable stages, making the overall process more controllable and less complex than simultaneous optimization of all parameters.
Solution Approach 2:
The patent develops a universal optimization framework that can evaluate multiple design parameters simultaneously using a standardized methodology. The same computational approach and evaluation criteria are applied across all parameter variations, creating a unified optimization process that handles the complexity systematically rather than requiring separate specialized methods for each parameter.
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 effectively reduces propeller noise levels while ensuring sufficient thrust and torque, validated through experimental measurements and computational analysis, providing a more efficient and accurate noise prediction method.
Implementation Method 1
A pressure difference is produced between the forward and rear surfaces of an airfoil-shaped blade, and a fluid (such as air or water) is accelerated behind the blade
Data Source
AI summary
A marine propeller having reduced noise characteristics, which has a hub having a central axis, one or more blades having a blade length with a proximal end attached to the hub and a distal end extending radially outward from the hub, wherein the propeller has a diameter in between 360 mm-400 mm, and wherein a combination of the diameter, pitch angle, skew angle, and number of blades of the propeller provides required thrust while generating low noise.