Passive Variable Pitch Propeller for Underwater Vehicles
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Solution Overview
Problem
Existing propeller designs, particularly for underwater vehicles, face inefficiencies due to fixed pitch propellers that compromise between low-speed and high-speed performance, and known variable pitch propellers rely on complex active controls, increasing cost and reducing reliability.
Innovation Solution
A passive variable pitch propeller assembly with a dynamically adjustable hub and spring plate mechanism that automatically adjusts propeller blade pitch based on rotation speed, utilizing hydrodynamic and centrifugal forces to optimize propulsion performance across a range of speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed pitch propeller is used, then the propeller is simple and reliable, but it compromises between low-speed and high-speed performance
Solution Approach 1:
The propeller blade pitch is made dynamically adjustable through a passive variable pitch mechanism. The blade can rotate about its longitudinal axis to change its pitch angle automatically based on operating conditions, allowing the same propeller to optimize performance across both low-speed and high-speed regimes without requiring multiple fixed pitch propellers or complex active control systems.
2Adaptability or versatility
If known variable pitch propellers use active controls, then pitch adjustment is possible, but device complexity and cost increase
Solution Approach 1:
The variable pitch mechanism is designed to be self-regulating and passive. It uses the propeller's own rotational motion and hydrodynamic forces to automatically adjust the blade pitch without requiring external power sources, control systems, or complex mechanisms. The blade rotates automatically in response to changes in water flow and rotational speed, making the system self-service and significantly simpler than active control systems.
3Adaptability or versatility
If known variable pitch propellers use complex mechanisms, then pitch control is achieved, but dependability decreases
Solution Approach 1:
The passive variable pitch mechanism eliminates complex control systems, motors, and electronic components that could fail. Instead, it relies on straightforward mechanical elements and hydrodynamic forces that are inherently more reliable. The blade pitch adjustment is driven by the propeller's own operation and water flow, making the system more dependable for underwater vehicle applications where reliability is critical.
4Productivity
If fixed pitch propeller is optimized for a small range of revolutions per minute, then it achieves maximum efficiency at designated operating condition, but efficiency is reduced at operating conditions outside the designated range
Solution Approach 1:
The propeller blade pitch is made dynamically adjustable through a passive variable pitch mechanism. The blade can rotate about its longitudinal axis to change its pitch angle automatically based on operating conditions, allowing the same propeller to optimize performance across both low-speed and high-speed regimes without requiring multiple fixed pitch propellers or complex active control systems.
Solution Approach 2:
The system changes the pitch angle parameter of the propeller blade dynamically based on operating conditions. By allowing the blade to rotate and adjust its pitch angle in response to changes in rotational speed and water flow, the propeller maintains optimal efficiency across a wide range of operating conditions rather than being optimized for a single designated speed.
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 provides efficient propulsion performance across varying speeds with reduced complexity and cost, minimizing weight and preventing blade stall at low speeds and over-speed at high speeds, while maintaining efficiency.
Implementation Method 1
The spring plate assembly provides a counterforce to the rotation of the propeller blades
Implementation Method 2
A spring transfers a dynamic load to the pressure flange of the spring plate
Implementation Method 3
a lift force generated by fluid flow over a propeller blade
Data Source
AI summary
A propeller pitch adjustment assembly is provided with a base hub operatively connected by blade shafts to propeller blades in which each blade rotates about an axis of each shaft. Each blade shaft is radially disposed about a propeller drive shaft and parallel to a pressure flange of a base hub spring plate. The spring plate counterforces the blade rotation with a lever screw that impacts the plate. An opposing spring transfers a load to the plate. The equilibrium position of the plate is determined by the spring force on the lever and a counteracting force exerted on the lever by a lift force generated by fluid flow over a propeller blade. A capping mechanism can provide a preload to the spring. A force exerted by the lift of the blade on the lever screw results in a blade pitch change.