Propulsion

About: Propulsion is a research topic. Over the lifetime, 24977 publications have been published within this topic receiving 200311 citations.

Hybrid power and propulsion systems for ships: Current status and future challenges

Abstract: Increasing environmental concerns are driving the shipping industry to take strict measures to deal with greenhouse gas emissions. International Maritime Organization drives the industry to find more efficient and environmentally friendly power systems. To mitigate harmful emissions, researches on marine alternative fuels, operational improvements like slow steaming or predictive maintenance, and additional emission abatement technologies are not sufficient. The use of electricity as the main energy vector is one of the ways to improve the shipping propulsion system's efficiency. In this study, power generation technologies, energy storage components, energy management systems, and hybrid propulsion topologies are reviewed. Diesel engines, fuel cells, solar and wind power as renewable energy sources are discussed as power generation units. On the energy storage side, batteries, supercapacitors, and flywheels are presented and described. Three common hybrid propulsion configurations, serial, parallel, and serial-parallel architectures are detailed with their pros and cons by highlighting commonly used energy management systems and optimization methods. Lastly, criteria for hybrid system selection are defined according to eight different ship types and assessed by providing a generic methodological approach. It is shown that electrical components and architectural design should be elaborated according to operational and architectural characteristics for ships. In short term, it is concluded that internal combustion engines are still the major hybridization element with different energy storage systems. New regulations on the mitigation of harmful emissions will accelerate the transition to hybrid power which is an important option for the ultimate zero-carbon shipping goal.

Using Low-Thrust Exhaust-Modulated Propulsion Fuel-Optimal Planar Earth-Mars Trajectories

Abstract: The determination of fuel-optimal, planar, Earth–Mars trajectories of spacecraft using low-thrust, variable speciŽ c impulse Isp propulsion is discussed. The characteristics of a plasma thruster currently being developed for crewed/cargomissions toMars are used. This device can generate variable Isp within the range of 1000–35,000s, at constant power. The state equationsarewritten in rotating, polar coordinates, and the trajectory is divided into two phases, patched together at an intermediate pointbetween the Earth andMars. The gravitationaleffects of the sun, Earth, andMars are included in the two phases. The formulationof the problem treats the spacecraft mass as a state variable, thus, coupling the spacecraft design to the trajectory design. The optimal control problem is solved using an indirect, multipleshootingmethod.Results for a 144-daycrewed mission toMars are presented. The variationof the Isp during spacecraft’s escape from the Earth’s gravitational Ž eld shows an interesting periodic behavior with respect to time. The results obtained are also compared with those obtained by assuming a three-phase trajectory, with the Earth, sun, and Mars, in uencing the spacecraft, one per phase, in sequence.

Numerical simulation of ship propulsion transients and full-scale validation

Abstract: The paper describes a mathematical model for the dynamics simulation of ship propulsion systems. The model, developed in a MATLAB-SIMULINK software environment, is structured in modular form; the v...