Propulsion

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

Techno-economical analysis of single pressure exhaust gas waste heat recovery systems in marine propulsion plants

Abstract: In this article, the waste heat recovery (WHR) installations used for the production of saturated steam and electric power for the cases of a two-stroke and a four-stroke engine propulsion plant of a typical merchant ship are investigated. The examined WHR system is considered to be of the single steam pressure type with an external heat exchanger for the heating of feed water entering into the boiler drum. The option of using the engine air cooler for heating the feed water was also examined. The WHR installation was modeled under steady-state conditions, and the derived WHR installation parameters for various engine loads are presented and analyzed. Furthermore, using the simulation results, the improvement of Energy Efficiency Design Index (EEDI) of the examined ship is calculated, and the impact of the WHR on the ship EEDI is discussed. In addition, following the technical evaluation of the alternative options for the ship propulsion plant, an economic study was performed for a typical ship voyage. The derived results were presented and discussed leading to conclusions for the most techno-economical propulsion system configuration.

Combined Cycle Propulsion: Aerojet Innovations for Practical Hypersonic Vehicles

Abstract: Sustained hypersonic (M>5) atmospheric flight is best performed with a supersonic combustion ramjet (Scramjet). Scramjet-powered flight with durations over 100 seconds (X51) has now been demonstrated. A Scramjet-powered vehicle requires a “boost” to its ramjet takeover (RTO) speed where it can provide adequate acceleration to its cruise speed. All Scramjet powered flights to date have used a solid rocket booster motor that was dropped just before RTO. Although this is practical for demonstration flights, it is unaffordable for an operational vehicle, particularly when the vehicle is to be reused. Reusable hypersonic vehicles require a synergistically integrated self boosting capability. In this paper, we describe the issues such propulsion systems must address and discuss various Aerojet solutions to make them practical.

Monowheel Type Vehicle

Abstract: An engine-propelled monowheel vehicle comprises two wheels, close together, that circumscribe the remainder of the vehicle. When the vehicle is moving forward, the closely spaced wheels act as a single wheel, and the vehicle turns by leaning the wheels. A single propulsion system provides a drive torque that is shared by the two wheels. A separate steering torque, provided by a steering motor, is added to one wheel while being subtracted from the other wheel, enabling the wheels to rotate in opposite directions for turning the vehicle at zero forward velocity. The vehicle employs attitude sensors, for sensing roll, pitch, and yaw, and an automatic balancing system. A flywheel in the vehicle spins at a high rate around a spin axis, wherein the spin axis is rotatable with respect to the vehicle's frame. The axis angle and flywheel spin speed are continually adjustable to generate torques for automatic balancing.

Ship propulsion unit with a main and an auxiliary propeller

Abstract: 1. Ship's propulsion system which is driven from a main machine, preferably a Diesel engine or a gas or steam turbine, and consists of a main propeller and a fixedly installed tandem propeller between main propeller and rudder or of a main propeller and a rudder which is constructed as active rudder with or without jet or as a pivotable propeller with of without gear nacelle and which for improvement of the overall propulsion efficiency and the rudder effect permanently corotates as counterpropeller, characterized thereby, that a part of the total mechanical output is taken off by a synchronous generator (5) arranged at the end face of the main machine (2) or in the shafting (3) and conducted by way of an electrical shaft to a polyphase alternating current motor which drives the tandem propeller (6, 16), that the generator (5), during starting and reversing and in derivation from the travel command generator signal, receives shock excitation until the polyphase alternating current motor has started or reversed and the excitation is regulated towards U/f = constant.