Showing papers on "Propulsion published in 2003"

Propulsion Systems for Hybrid Vehicles

Abstract: The automotive industry is waking up to the fact that hybrid electric vehicles could provide an answer to the ever-increasing need for lower-polluting and more fuel-efficient forms of personal transport. This is the first book to give comprehensive coverage of all aspects of the hybrid vehicle design, from its power plant and energy storage systems, to supporting chassis subsystems necessary for realising hybrid modes of operation. Key topics covered include hybrid propulsion system architectures, propulsion system sizing, electric traction system sizing and design, loss mechanisms, system simulation and vehicle certification.

Self propelled device

Abstract: A sensing device includes a propulsion system that is typically substantially or completely within the sensing device. The propulsion system may include, for example, a rotatable propeller. The sensing device may be an in-vivo autonomous capsule with an imager, but may be another type of sensing device.

System Performance and Thermodynamic Cycle Analysis of Airbreathing Pulse Detonation Engines

Abstract: A modular approach to the study of system performance and thermodynamic cycle efficiency of airbreathing pulse detonation engines (PDEs) is described. Each module represents a specific component of the engine, and its dynamic behavior is formulated using conservation laws in either one or two spatial dimensions. A framework is established for assessing quantitatively the influence of all known processes on engine dynamics. Various loss mechanisms limiting the PDE performance are identified. As a specific example, a supersonic PDE for high-altitude applications is studied comprehensively. The effects of chamber configuration and operating sequence on the engine propulsive efficiency are examined. The results demonstrate the existence of an optimum cycle frequency and valve close-up time for achieving maximum performance in terms of thrust and specific impulse. Furthermore, a choked convergent-divergent nozzle is required to render the PDE competitive with other airbreathing propulsion systems, such as gas-turbine and ramjet engines.

Role of anomalous electron transport in a stationary plasma thruster simulation

Abstract: Stationary plasma thrusters (SPTs) are advanced propulsion devices that use a gas discharge to ionize and accelerate the propellant We present simulation results obtained with a two-dimensional hybrid model of an SPT discharge The model characterizes the ill-understood anomalous electron transport in SPTs by empirical parameters, of which we demonstrate the influence on the simulation results Although no optimal values for these parameters can clearly be identified, the model predicts many features of the SPT behavior and yields interesting insights in the SPT physics Experimentally observed electric potential distributions can only be reproduced if the anomalous electron transport is assumed to be stronger outside than inside the SPT channel The simulations reproduce experimentally measured oscillations at 10–20 kHz and predict additional oscillations at 100–200 kHz We discuss the dynamics of these oscillations and their influence on the energy distribution of the ion beam leaving the thruster

Advanced Space Propulsion for the 21st Century

Abstract: HE overriding goal of advanced space propulsion is to reduce the costs of doing space missions, and to enable totally new types of missions that basically could not be performed (even at essentially unlimited cost) with existing technology. For example, with Earth-launch costs on the order of $10,000 per kilogram (comparable to the current cost of gold!) of delivered payload, one important application of advanced propulsion is to reduce thecostofaccessto space(andtransportation oncein space), both in the initial Earth-launch vehicle and then in the in-space vehicles, by reducing the total mass (most of which is propellant) that must be launched from Earth. This can be achieved by either developing more efe cient, higher-performance (i.e., higher specie c impulse Isp/ propulsion technologies, or by reducing the propellant requirements by reducing dry mass, mission velocity 1V, and so on. (Note however that launch cost is strongly driven by launch frequency; 1 thus, some advanced propulsion concepts attempt to both improve performance and increase launch rate.) A second goal of advanced propulsion is the ability to perform previously “ impossible” missions. An example of an impossible mission is attempting an interstellar mission using chemical propulsion. No matter how large the rocket, no matter how many stages it has, you simply cannot achieve the speeds (typically at least 10%of the speed of light) required for a practical interstellar mission using a chemical propulsion system. More generally, it is not practical to performaspace mission wherethe mission 1V isgreater than afew (e.g., two to three) times the propulsion system’ s exhaust velocity Vexhaust or, equivalently, Isp. Ultimately,theperformanceofanyrocketislimitedbytheRocket

Introduction to Aircraft Flight Mechanics: Performance, Static Stability, Dynamic Stability, and Classical Feedback Control

Abstract: A Review of Basic Aerodynamics A Review of Basic Propulsion Aircraft Performance Aircraft Equations of Motion Aircraft Static Stability Linearizing the Equations of Motion Aircraft Dynamic Stability Classical Feedback Control Aircraft Stability/Control Augmentation Special Topics Appendices.

Follow-On Technology Requirement Study for Advanced Subsonic Transport

Abstract: A study was conducted to define and assess the critical or enabling technologies required for a year 2005 entry into service (EIS) engine for subsonic commercial aircraft, with NASA Advanced Subsonic Transport goals used as benchmarks. The year 2005 EIS advanced technology engine is an Advanced Ducted Propulsor (ADP) engine. Performance analysis showed that the ADP design offered many advantages compared to a baseline turbofan engine. An airplane/ engine simulation study using a long range quad aircraft quantified the effects of the ADP engine on the economics of typical airline operation. Results of the economic analysis show the ADP propulsion system provides a 6% reduction in direct operating cost plus interest, with half the reduction resulting from reduced fuel consumption. Critical and enabling technologies for the year 2005 EIS ADP were identified and prioritized.

Scalable Solar-Sail Subsystem Design Concept

Abstract: A scalable solar-sail concept, which integrates recently developed gossamer coilable longeron mast technology, has been developed, providing simple reliable deployment and structural robustness with minimum weight. This sail system is also unique in that it is composed of tensioned membranes without the incorporation of catenaries. This simplification is made possible through a mathematical demonstration of the insignificance of structural wrinkles on propulsive effectiveness. The sail package is a mass-optimized propulsion subsystem that can be mounted to a general heritage spacecraft to provide continuous low-level thrust. The design baseline is a three-axis-stabilized four-quadrant 40-m-square sail with attitude controlled by gimbaling the spacecraft on an extended boom. Considerations for the baseline design definition and the resulting performance vs size are reviewed.

Drive control apparatus for hybrid vehicle

Abstract: A rotational shaft receives drive power from an engine and a first motor, and drives front wheels through front clutches. A second motor drives rear wheels. The first motor and the second motor are supplied with electric power from a battery. A main ECU controls an electric vehicle mode in which the first clutches are disengaged, the supply of fuel to the engine is stopped, and the second motor drives the rear wheels to propel a hybrid vehicle, by dividing the electric vehicle mode into a first propulsion mode and a second propulsion mode. In the first propulsion mode, the first motor is de-energized. In the second propulsion mode, a load imposed on the second motor is greater than that of the first propulsion mode, and the first motor is supplied with electric power to rotate the rotational shaft at a predetermined speed.

Using Camless Valvetrain for Air Hybrid Optimization

Abstract: The air-hybrid engine absorbs the vehicle kinetic energy during braking, puts it into storage in the form of compressed air, and reuses it to assist in subsequent vehicle acceleration In contrast to electric hybrid, the air hybrid does not require a second propulsion system This approach provides a significant improvement in fuel economy without the electric hybrid complexity The paper explores the fuel economy potential of an air hybrid engine by presenting the modeling results of a 25L V6 spark-ignition engine equipped with an electrohydraulic camless valvetrain and used in a 4531 kg passenger car It describes the engine modifications, thermodynamics of various operating modes and vehicle driving cycle simulation The air hybrid modeling projected a 64% and 12% of fuel economy improvement over the baseline vehicle in city and highway driving respectively This is possible without reducing the vehicle weight to compensate for additional hardware and without reducing engine displacement

Hybrid vehicle employing hybrid system

Abstract: In a hybrid electric vehicle (HEV) employing a hybrid system using both an internal combustion engine and a second motor/generator as a propelling power source for vehicle propulsion, and also employing a first generator driven by the engine for power generation, an integrated HEV control system is provided to control the engine, and the first and second motor/generators. The integrated HEV control system permits operation of only the second motor/generator as the propelling power source to establish a motor propelled vehicle driving mode and simultaneously basically inhibits operation of the engine, when satisfying at least a condition that the engine misfire occurs. If a power generation requirement or a battery recharge requirement is present during the misfire period, operation of the engine is temporarily permitted for driving the first motor/generator only for a battery recharge.

Development of a Turbofan Engine Simulation in a Graphical Simulation Environment

Abstract: This paper presents the development of a generic component level model of a turbofan engine simulation with a digital controller, in an advanced graphical simulation environment. The goal of this effort is to develop and demonstrate a flexible simulation platform for future research in propulsion system control and diagnostic technology. A previously validated FORTRAN-based model of a modern, high-performance, military-type turbofan engine is being used to validate the platform development. The implementation process required the development of various innovative procedures, which are discussed in the paper. Open-loop and closed-loop comparisons are made between the two simulations. Future enhancements that are to be made to the modular engine simulation are summarized.

Hybrid electric vehicle incorporating an integrated propulsion system

Abstract: A hybrid electric vehicle drive system comprising a combustion engine, an electric motor and at least one nickel metal hydride battery module forming a power source for providing electric power to the electric motor, the at least one nickel metal battery module having a peak power density in relation to energy density as defined by: P>1,420−16E where P is the peak power density as measured in Watts/kilogram and E is the energy density as measured in Watt-hours/kilogram.

Stationary plasma thrusters operate in space

Abstract: The first EOL-1 flight propulsion system with a stationary plasma thruster created at the Fakel Experimental and Design Bureau (EDB) on the basis of an experimental thruster designed and tested at the Kurchatov Institute of Atomic Energy is described. Subsequent versions of the EOL-type systems designed at the Fakel EDB using M-70, M-100, and other thrusters are reviewed. The current state of work on stationary plasma thrusters in the world is analyzed. The Phobos-Grunt project, whose aim is to deliver soil samples from Phobos and which implies the use of stationary plasma thrusters, is discussed.

Superconducting motors and generators for naval applications

Abstract: The US Navy is planning for a transition to electric warships as future ship combatants. Superconducting motors for propulsion and superconducting generators for power conversion are under active development (motors) or strong consideration (generators). This article describes the fundamentals of motor technology, as it applies to the Navy, how superconductivity leads to advantages in power density and quietness, and how the technology issues faced in the development of full scale naval motors are being addressed. Finally, the status of the naval superconducting propulsion power projects will be presented.

Modeling of iron losses in permanent magnet synchronous motors with field-weakening capability for electric vehicles

Abstract: Recent advancements of permanent magnet (PM) materials and solid-state devices have contributed to a substantial performance improvement of permanent magnet machines. Owing to the rare-earth PMs, these motors have higher efficiency, power factor, output power per mass and volume, and better dynamic performance than induction motors without sacrificing reliability. Not surprisingly. they are continuously receiving serious considerations for a variety of automotive and propulsion applications. An electric vehicle (EV) requires a high-efficient propulsion system having a wide operating range and a capability of generating a high peak torque for short durations. The improvement of torque-speed performance for these systems is consequently very important, and researches in various aspects are therefore being actively pursued. A great emphasis has been placed on the efficiency and optimal utilization of PM machines. This requires attention to many aspects related to the machine design and overall performance. In this respect, the prediction of iron losses is particularly indispensable and challenging, especially for drives with a deep field-weakening range. The objective of this paper is to present iron loss estimations of a PM motor over a wide speed range. As. aforementioned, in EV applications core losses can be significant during high-speed operation and it is imperative to evaluate these losses accurately and take them into consideration during the motor design stage. In this investigation. the losses are predicted by using an analytical model and a 2D time-stepped finite element method (FEM). The results from different analytical approaches are compared with the FEM computations. The validity of each model is then evaluated by these comparisons.

Dc power system for marine vessels

Abstract: An embodiment of the invention is a power system for a marine vessel including a plurality of power sources (20). A propulsion power distribution unit is coupled to the plurality of primary power sources (20). A plurality of propulsion devices (30) are coupled to the propulsion power distribution unit. A weaponry power distribution unit is coupled to the propulsion power distribution unit. A plurality of directed energy weapons (50) are coupled to the weaponry power distribution unit.

New Challenges to Trajectory Design by the Use of Electric Propulsion and Other New Means of Wandering in the Solar System

Abstract: The design of spacecraft trajectories is a crucial part of a space mission design. Often the mission goal is tightly related to the spacecraft trajectory. A geostationary orbit is indeed mandatory for a stationary equatorial position. Visiting a solar system planet implies that a proper trajectory is used to bring the spacecraft from Earth to the vicinity of the planet. The first planetary missions were based on conventional trajectories obtained with chemical engine rockets. The manoeuvres could be considered 'impulsive' and clear limitations to the possible missions were set by the energy required to reach certain orbits. The gravity-assist trajectories opened a new way of wandering through the solar system, by exploiting the gravitational field of some planets. The advent of other propulsion techniques, as electric or ion propulsion and solar sail, opened a new dimension to the planetary trajectory, while at the same time posing new challenges. These 'low thrust' propulsion techniques cannot be considered 'impulsive' anymore and require for their study mathematical techniques which are substantially different from before. The optimisation of such trajectories is also a new field of flight dynamics, which involves complex treatments especially in multi-revolution cases as in a lunar transfer trajectory. One advantage of these trajectories is that they allow to explore regions of space where different bodies gravitationally compete with each other. We can exploit therefore these gravitational perturbations to save fuel or reduce time of flight. The SMART-1 spacecraft, first European mission to the Moon, will test for the first time all these techniques. The paper is a summary report on various activities conducted by the project team in these areas.

Design and flight test results for micro-sized fixed-wing and vtol aircraft

Abstract: There has been recent interest in unmanned air vehicles with a largest linear dimension no greater than 6 inches. Micro sized air vehicles (µAV) are intended to operate close to a point of interest without detection and provide surveillance teams with critical information in life threatening situations that is currently not available in a rapid-deployment urban-environment mission scenario. This paper studies the importance of aerodynamics, propulsion, and mission requirements on the design of a µAV. A Multi-Disciplinary Optimization method is used to size µAV’s for a baseline mission. Sensitivity studies of the optimized designs identify features that most strongly affect its performance. Electric and internal combustion engine propulsion are compared. Results of these analyses show that large energy density, power density, and maximum lift capability are the most important features of successful µAV’s and that ICE power is superior to electric because of its larger power density. The results also show that increases in parasite drag due to low Reynolds number is of minor importance so long as lift capability is maintained. Maneuverability constraints have the strongest influence on µAV size because smaller turn radii require lower wing loadings and for a fixed weight this implies larger wing area and size. Three radio controlled prototypes of µAV’s were built and test flown based on the design study results. These vehicles are a 9 inch span electric powered fixed-wing, a 6 inch span ICE powered fixed-wing, and a 7 inch diameter ICE powered VTOL design. Each design has been flown successfully as a radio control aircraft and the flight test results revealed several unexpected difficulties relating to aircraft stability, control, and propulsion system integration. Further numerical analysis of the VTOL design shows that the size penalty for VTOL capability is negligible and that a 6 inch tail-sitter µAV can perform all of the mission requirements and operate in VTOL and translational flight modes.

Design and performance tests of cycloidal propulsion systems

Abstract: The cycloidal propeller, which can be described as a horizontal rotary wing, offers powerful thrust levels, and a unique ability to change the direction of the thrust almost instantly. In this work, cycloidal propulsion system was designed and implemented with sinusoidal low pitch system to investigate the fundamental characteristics of hovering states. Before experimental study, computational analysis was made in commercial CFD tool, CD Adopco/StarCD. This work gives schematic view of flow field around rotor. And it predicts the load variation on a blade with respect to revolution and the total thrust from cycloidal rotor, at specific condition. CFD analysis also makes it possible to check the camber effect. The propulsion system was built up with sinusoidal low pitch control mechanism. Thrust, power and efficiency were measured for various conditions of parameter setting. It was accomplished by designing the equipment which can change the rotational radius, number of blade, phase angle of eccentricity and amplitude of eccentricity.

Steerable, intermittently operable rocket propulsion system

Abstract: A propulsion system including an extinguishable rocket motor and an incorporated maneuver control system. The rocket motor may be of the solid fuel type. One or more proportional axial thrust valves in communication with a pressure vessel or motor case containing a solid fuel propellant may be used to release combustion products for creating axial thrust. A plurality of proportional maneuver control valves in communication with the pressure vessel and having associated maneuver control thrusters may be selectively actuated in different modes of operation to provide control of pitch, yaw and roll. Fully opening all valves in communication with the pressure vessel may be used to cause rapid depressurization to extinguish the propellant. Reignition of the rocket motor may be effected upon repressurization of the pressure vessel through closing at least some of the valves. Ignition grains may be employed to shorten reignition time, and multiple propellant grains may be provided for multiple pulses.