Variable Pitch Propeller Torque Optimization
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Solution Overview
Problem
The existing propulsion mode with a single engine activated per shaft line is inefficient, leading to degraded propulsion efficiency and increased fuel consumption, as the propeller operates outside its optimal range.
Innovation Solution
A method that increases the propeller pitch to enhance torque on the propeller shaft while reducing the motor shaft's rotational speed, maintaining power output and reducing fuel consumption by activating only one engine and deactivating the coupled alternator, with the generating sets producing electrical power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the propeller pitch is increased to enhance torque on the propeller shaft, then the propulsion efficiency is improved, but the motor shaft's rotational speed decreases
Solution Approach 1:
The patent changes the operating parameters of the propulsion system by increasing the propeller pitch angle and reducing the motor shaft rotational speed simultaneously. This parameter transformation allows the propeller to operate at optimal pitch conditions for efficient thrust generation while the motor operates at reduced speed to maintain power output, thereby resolving the contradiction between propulsion efficiency and rotational speed.
2Loss of energy
If only one engine is activated per shaft line, then the fuel consumption is reduced, but the propulsion efficiency is degraded
Solution Approach 1:
The patent transforms the operating parameters of the single activated engine by adjusting the propeller pitch to optimal values and optimizing the motor shaft speed. This parameter optimization enables the single engine to operate in a high-efficiency region of its performance curve, compensating for the reduced total power output and maintaining propulsion efficiency while achieving fuel savings from operating fewer engines.
3Loss of energy
If the coupled alternator is deactivated, then the fuel consumption is reduced, but the electrical power supply capability is affected
Solution Approach 1:
The patent extracts the electrical power generation function from the deactivated coupled alternator and assigns it to the generator sets. This functional extraction allows the coupled alternator to be deactivated for fuel savings while the generator sets independently provide the necessary electrical power supply, resolving the contradiction between energy efficiency and power supply capability.
4Device complexity
If the propeller operates outside its optimal range, then the system configuration is simpler, but the propulsion efficiency is degraded
Solution Approach 1:
The patent introduces dynamic adjustment of the propeller pitch angle to maintain optimal operating conditions. By making the propeller pitch variable rather than fixed, the system can adapt to different operating scenarios and keep the propeller within its optimal efficiency range, resolving the contradiction between system simplicity and propulsion efficiency.
Data Source
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AI summary
The invention relates to a method and a system for modifying the propulsion of a ship, which propulsion is provided by at least one shaft line comprising: - a variable-pitch propeller secured to a propeller shaft, - two engines each comprising a drive shaft. The ship initially sails in a configuration where: - the generator sets provide the electrical energy, - a single engine per shaft line is activated to provide the propulsive energy, The initial power developed by said activated engine, as a function of the initial value of the propeller pitch and the nominal rotational speed of the drive shaft of said activated engine, generates an initial cruising speed of the ship.In this navigation configuration, new control instructions are issued that are adapted to set: - a new propeller pitch that increases the torque on the propeller shaft, - a new rotation speed of the motor shaft of the activated motor that is lower than the nominal rotation speed of said motor shaft. The settings of the new propeller pitch and the new rotation speed of the motor shaft are made so that the power developed by the activated motor is maintained at its initial value, or at a value close to this initial value, and so that the ship sails at a new cruising speed that is higher than the initial cruising speed.