Showing papers on "Propulsion published in 2000"

Fundamentals of Stationary Plasma Thruster Theory

Abstract: This review is devoted to very specific processes in stationary plasma propulsion devices with poloidal magnetic and electric fields and a dielectric channel (Fig. 1) [1—3]. At present, these accelerators with closed-drift electrons and an extended acceleration region (also called Hall thrusters) generate quasineutral multi-ampere (~ 1 — 50 A) streams of ions of different species (from hydrogen to xenon) with particle energies of 50— 1000 eV. They are mostly known as electric propulsion thrusters for spacecraft (see the Appendix for more details). Therefore, such devices are more frequently called “stationary plasma thrusters” (SPTs). We will use this term throughout the paper. SPTs were designed in 1960s from the basic idea of A. I. Morozov at the Kurchatov Atomic Energy Institute (AEI) (G. Ya. Shchepkin’s laboratory). They were first launched into space in 1971 [4] and have since (most recently in 1997) been mounted onboard more than 50 Russian satellites. From 1999, these thrusters should be used on USA satellites and then perhaps on the satellites of other countries.

Mini-Magnetospheric Plasma Propulsion: Tapping the energy of the solar wind for spacecraft propulsion

Abstract: Mini-Magnetospheric Plasma Propulsion is a potentially revolutionary plasma propulsion concept that could enable spacecraft to travel out of the solar system at unprecedented speeds of 50 to 80 km s -1 or could enable travel between the planets for low power requirements of ∼ 1 kW per 100 kg of payload and 0.5 kg fuel consumption per day for acceleration periods of several days to a few weeks. The high efficiency and specific impulse attained by the system are due to its utilization of ambient energy, in this case the energy of the solar wind, to provide the enhanced thrust. Coupling to the solar wind is produced through a large-scale magnetic bubble or mini-magnetosphere generated by the injection of plasma into the magnetic field supported by solenoid coils on the spacecraft. This inflation is driven by electromagnetic processes, so that the material and deployment problems associated with mechanical sails are eliminated.

Driving force control system for automotive vehicle

Abstract: A driving force control system for an automotive vehicle using driving torque produced by at least one of an internal combustion engine and an electric motor for propulsion, and including a battery and a power-transmission mechanism having a continuously variable transmission, comprises sensors detecting vehicle speed, engine speed, an accelerator operating amount, a state of charge of the battery. An electronic control unit calculates a target engine speed needed to realize the vehicle speed, the target driving torque and the target generated electric energy at the lowest fuel consumption, considering an efficiency of each of the engine, the electric motor, and the power-transmission mechanism, so as to operate the engine, the electric motor, and/or the power-transmission mechanism always at their optimum operating points depending on the ratio of a first time rate of doing work for the driver's required driving torque to a second time rate of doing work for the required generated electric energy, as well as the sum of the first and second time rates.

Simplified docking method and apparatus for a multiple engine marine vessel

Abstract: A docking system is provided which utilizes the marine propulsion unit of a marine vessel, under the control of an engine control unit that receives command signals from a joystick or push button device, to respond to a maneuver command from the marine operator. The docking system does not require additional propulsion devices other than those normally used to operate the marine vessel under normal conditions. The docking or maneuvering system of the present invention uses two marine propulsion units to respond to an operator's command signal and allows the operator to select forward or reverse commands in combination with clockwise or counterclockwise rotational commands either in combination with each other or alone.

GSP: A Generic Object-Oriented Gas Turbine Simulation Environment

Abstract: NLR’s primary tool for gas turbine engine performance analysis is the ‘Gas turbine Simulation Program’ (GSP), a component based modeling environment. GSP’s flexible object-oriented architecture allows steady-state and transient simulation of any gas turbine configuration using a user-friendly drag&drop interface with on-line help running under Windows95/98/NT.GSP has been used for a variety of applications such as various types of off-design performance analysis, emission calculations, control system design and diagnostics of both aircraft and industrial gas turbines. More advanced applications include analysis of recuperated turboshaft engine performance, lift-fan STOVL propulsion systems, control logic validation and analysis of thermal load calculation for hot section life consumption modeling.In this paper the GSP modeling system and object-oriented architecture are described. Examples of applications for both aircraft and industrial gas turbine performance analysis are presented.Copyright © 2000 by ASME

The Numerical Propulsion System Simulation: An Overview

Abstract: Advances in computational technology and in physics-based modeling are making large-scale, detailed simulations of complex systems possible within the design environment. For example, the integration of computing, communications, and aerodynamics has reduced the time required to analyze major propulsion system components from days and weeks to minutes and hours. This breakthrough has enabled the detailed simulation of major propulsion system components to become a routine part of designing systems, providing the designer with critical information about the components early in the design process. This paper describes the development of the numerical propulsion system simulation (NPSS), a modular and extensible framework for the integration of multicomponent and multidisciplinary analysis tools using geographically distributed resources such as computing platforms, data bases, and people. The analysis is currently focused on large-scale modeling of complete aircraft engines. This will provide the product developer with a "virtual wind tunnel" that will reduce the number of hardware builds and tests required during the development of advanced aerospace propulsion systems.

An Investigation of Electric Motor Drive Characteristics for EV and HEV Propulsion Systems

Abstract: The recent growing interest in electric vehicle (EV) and hybrid electric vehicle (HEV) demands for an efficient, reliable and economical motor drive for electric propulsion. However, searching for a suitable traction motor becomes quite involved when vehicle dynamics and system architecture are considered. This paper makes an in-depth investigation on two highly important traction motor characteristics, extended speed rangeability and energy efficiency, from vehicular system perspective. The influences of these two motor drive features on a pure EV, a post-transmission, and two pretransmission parallel HEV with 20% and 50% hybridization are studied in this paper. Two EV-HEV software packages ‘V-ELPH’ developed by Texas A&M University and ‘ADVISOR’ from NREL are used for simulation purposes. Based on the results in this paper, a systematic method is developed regarding the selection of traction drives for EV and HEV propulsion systems.

Turbofan engine control design using robust multivariable control technologies

Abstract: A unified robust multivariable approach to propulsion control design has been developed at NASA Glenn Research Center. The critical elements of this unified approach are: a robust H/sub /spl infin// control synthesis formulation; a simplified controller scheduling scheme; and a new approach to the synthesis of integrator windup protection gains for multivariable controllers. This paper presents results from an application of these technologies to control design for linear models of an advanced turbofan engine. The objectives of the study were to transfer technology to industry and to identify areas of further development for the technology. The technology elements and industrial development of tools to implement the steps are described with respect to their application to a GE variable-cycle turbofan engine. A set of three-input/three-output three-state linear engine models was used over a range of power levels covering engine operation from idle to maximum unaugmented power. Results from simulation evaluation are discussed and insight is provided into how the design parameter choices affect the results.

Bare Tethers for Electrodynamic Spacecraft Propulsion

Abstract: Electrodynamic tether thrusters can use the power provided by solar panels to drive a current in the tether and then the Lorentz force to push against the Earth's magnetic field, thereby achieving propulsion without the expenditure of onboard energy sources or propellant. Practical tether propulsion depends critically on being able to extract multiamp electron currents from the ionosphere with relatively short tethers (10 km or less) and reasonably low power. We describe a new anodic design that uses an uninsulated portion of the metallic tether itself to collect electrons. Because of the efficient collection of this type of anode, electrodynamic thrusters for reboost of the International Space Station and for an upper stage capable of orbit raising, lowering, and inclination changes appear to be feasible. Specifically, a 10-km-long bare tether, utilizing 10 kW of the space station power could save most of the propellant required for the station reboost over its 10-year lifetime. The propulsive small expendable deployer system experiment is planned to test the bare-tether design in space in the year 2000 by deploying a 5-km bare aluminum tether from a Delta II upper stage to achieve up to 0.5-N drag thrust, thus deorbiting the stage.

2020 vision : the prospects for large civil aircraft propulsion

Abstract: This paper will examine the prospects for propulsion systems for large civil transport aircraft over the next two decades, to the year 2020. This period is likely to see the market drivers for future propulsion system development change from the more traditional ones of fuel consumption and weight, to also include those that affect the impact of civil aviation on the environment, and the continuing pressure to reduce the cost of ownership of civil engines, namely, product unit cost, maintenance costs and reliability. Fifty years of civil aero-engine development are reviewed and trends showing the likely limits to the main engine performance parameters are provided. The paper concludes with consideration of a number of new civil aircraft and engine concepts that may emerge in the next 20 years

Mars Missions Using Solar Electric Propulsion

Abstract: Successful demonstration of solar electric propulsion on the Deep Space 1 technology demonstration mission has paved the way for the use of this technology on future planetary missions. Currently there is much interest in retrieving Mars surface samples for scientiŽ c exploration, as well as developing the technology to enable human missions to Mars sometime in the next few decades. Solar electric propulsion trajectories for Mars opportunities in the 2004–2011 time frame are examined. All of the trajectories shown were optimized with a gradient based calculus-of-variations tool. In addition, a genetic algorithmwas used to search for more nonstandard trajectories. Mission performance is presented as burnout mass along contours of constant  ight time. The superior speciŽ c impulse of these propulsionsystems results in a largerdeliveredmass atMars thana conventionalchemicalmission. A very curious feature of these missions is that for longer  ight times solutionsexist that permit a nearly continuous launch opportunity over an entire Earth–Mars synodic period.

Mission Advantages of Constant Power, Variable Isp Electrostatic Thrusters

Abstract: Electric propulsion has moved from station-keeping capability for spacecraft to primary propulsion with the advent of both the Deep Space One asteroid flyby and geosynchronous spacecraft orbit insertion. In both cases notably more payload was delivered than would have been possible with chemical propulsion. To provide even greater improvements electrostatic thruster performance could be varied in specific impulse, but kept at constant power to provide better payload or trip time performance for different mission phases. Such variable specific impulse mission applications include geosynchronous and low earth orbit spacecraft stationkeeping and orbit insertion, geosynchronous reusable tug missions, and interplanetary probes. The application of variable specific impulse devices is shown to add from 5 to 15% payload for these missions. The challenges to building such devices include variable voltage power supplies and extending fuel throughput capabilities across the specific impulse range.

The physics and engineering of the vasimr engine

Abstract: The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is a high power, radio frequency-driven magnetoplasma rocket, capable of I s]/thrust modulation at constant power. The physics and engineering of this device have been under study since 1980. The plasma is produced in an integrated plasma injector by a helicon discharge. However, the bulk of the plasma energy is added downstream by ion cyclotron resonance. The system features a magnetic nozzle, which accelerates the plasma particles by converting their azimuthal energy into directed momentum. A NASA-led, research effort, involving several teams in the United States, continues to explore the physics and engineering of the VASIMR, and its extrapolation as a high power, in-space propulsion system. These studies have produced attractive results in a number of areas, involving plasma theory and experiments, systems engineering and mission analysis. A conceptual point design for a 10 kW space demonstrator experiment has been completed.

AST Critical Propulsion and Noise Reduction Technologies for Future Commercial Subsonic Engines: Separate-Flow Exhaust System Noise Reduction Concept Evaluation

Abstract: This report describes the work performed by General Electric Aircraft Engines (GEAE) and Allison Engine Company (AEC) on NASA Contract NAS3-27720 AoI 14.3. The objective of this contract was to generate quality jet noise acoustic data for separate-flow nozzle models and to design and verify new jet-noise-reduction concepts over a range of simulated engine cycles and flight conditions. Five baseline axisymmetric separate-flow nozzle models having bypass ratios of five and eight with internal and external plugs and 11 different mixing-enhancer model nozzles (including chevrons, vortex-generator doublets, and a tongue mixer) were designed and tested in model scale. Using available core and fan nozzle hardware in various combinations, 28 GEAE/AEC separate-flow nozzle/mixing-enhancer configurations were acoustically evaluated in the NASA Glenn Research Center Aeroacoustic and Propulsion Laboratory. This report describes model nozzle features, facility and data acquisition/reduction procedures, the test matrix, and measured acoustic data analyses. A number of tested core and fan mixing enhancer devices and combinations of devices gave significant jet noise reduction relative to separate-flow baseline nozzles. Inward-flip and alternating-flip core chevrons combined with a straight-chevron fan nozzle exceeded the NASA stretch goal of 3 EPNdB jet noise reduction at typical sideline certification conditions.

Apparatus and method for maintaining state of charge in vehicle operations

Abstract: A propulsion system for use in a hybrid vehicle, wherein a first propulsion system provides a driving force to a first pair of wheels and a second propulsion system provides a driving force to a second pair of wheels. A system controller actuates the propulsion systems determines the necessary commands to be provided to the first and second propulsion systems so as to provide the vehicle with the most efficient driving and/or stopping force.

Propulsive Small Expendable Deployer System Experiment

Abstract: Relatively short electrodynamic tethers can extract orbital energy to 'push' against a planetary magnetic field to achieve propulsion without the expenditure of propellant. The Propulsive Small Expendable Deployer System experiment will use the flight-proven Small Expendable Deployer System (SEDS) to deploy a 5 km bare copper tether from a Delta II upper stage to achieve approximately 0.4 N drag thrust, thus lowering the altitude of the stage. The experiment will use a predominantly 'bare' tether for current collection in lieu of the endmass collector and insulated tether approach used on previous missions. The flight experiment is a precursor to a more ambitious electrodynamic tether upper stage demonstration mission which will be capable of orbit raising, lowering and inclination changes - all using electrodynamic thrust. The expected performance of the tether propulsion system during the experiment is described.

Aerodynamic Database Development for the Hyper-X Airframe Integrated Scramjet Propulsion Experiments

Abstract: This paper provides an overview of the activities associated with the aerodynamic database which is being developed in support of NASA''s Hyper-X scramjet flight experiments. Three flight tests are planned as part of the Hyper-X Program. Each will utilize a small, non-recoverable research vehicle with an airframe integrated scramjet propulsion engine. The research vehicles will be individually rocket boosted to the scramjet engine test points at Mach 7 and Mach 10. The research vehicles will then separate from the first stage booster vehicle and the scramjet engine test will be conducted prior to the terminal decent phase of the flight. An overview is provided of the activities associated with the development of the Hyper-X aerodynamic database, including wind tunnel test activities and parallel CFD analysis efforts for all phases of the Hyper-X flight tests. A brief summary of the Hyper-X research vehicle aerodynamic characteristics is provided, including the direct and indirect effects of the airframe integrated scramjet propulsion system operation on the basic airframe stability and control characteristics. Brief comments on the planned post flight data analysis efforts are also included.

Hyper-X Research Vehicle (HXRV) Experimental Aerodynamics Test Program Overview

Abstract: This paper provides an overview of the experimental aerodynamics test program to ensure mission success for the autonomous flight of the Hyper-X Research Vehicle (HXRV). The HXRV is a 12-ft long, 2700 lb lifting body technology demonstrator designed to flight demonstrate for the first time a fully airframe integrated scramjet propulsion system. Three flights are currently planned, two at Mach 7 and one at Mach 10, beginning in the fall of 2000. The research vehicles will be boosted to the prescribed scramjet engine test point where they will separate from the booster, stabilize. and initiate engine test. Following 5+ seconds of powered flight and 15 seconds of cowl-open tares, the cowl will close and the vehicle will fly a controlled deceleration trajectory which includes numerous control doublets for in-flight aerodynamic parameter identification. This paper reviews the preflight testing activities, wind tunnel models, test rationale. risk reduction activities, and sample results from wind tunnel tests supporting the flight trajectory of the HXRV from hypersonic engine test point through subsonic flight termination.

Deep Space One Investigations of Ion Propulsion Plasma Environment

Abstract: J. Wang¤ and D. E. Brinza† Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 D. T. Young‡ Southwest Research Institute, San Antonio, Texas 78228 J. E. Nordholt§ Los Alamos National Laboratory, Los Alamos, New Mexico 87545 J. E. Polk¶ and M. D. Henry¤ ¤ Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 R. Goldstein††and J. J. Hanley‡‡ Southwest Research Institute, San Antonio, Texas 78228 and D. J. Lawrence and M. Shappirio§§ Los Alamos National Laboratory, Los Alamos, New Mexico 87545

Propulsion system performance enhancements on REMUS AUVs

Abstract: This paper details recent efforts on drag reduction, vehicle shape and propulsion system modifications, and propeller design for the REMUS class of autonomous underwater vehicles (AUV). Drag reduction was accomplished by tow-tank measurements of an existing design to itemize the sources of drag. The vehicle shape and main propulsion system were modified to use magnetic torque transfer through a seawater collar to eliminate a rotating shaft seal. Propeller design efforts consisted first of a trade-off analysis of blade number, RPM, vehicle speed and blade shape to determine an optimum design and then refinement of that design for production version. The combined effect of these efforts resulted in a four fold reduction in propulsion power at the same speed of the previous design, and an increase in maximum achievable speed by almost a factor of two. These propulsion system performance improvements combined with recent changes in energy capacity for the vehicle result in a total per mission range of 120 km at 1.5 m/s for an endurance of 20 hours.

Multi-unit articulated road train propulsion system

Abstract: A distributed propulsion system is provided for a multi-unit articulated road train. The distributed propulsion system includes a tractor having a first propulsion system for propelling the tractor. A trailer is secured to the tractor at an articulated joint, such as a fifth wheel or draw bar connection. The tractor has a second propulsion system for substantially propelling the trailer. A load sensor for detecting a load between the tractor and the trailer, preferably the tensile load, is associated with the articulated joint. The load sensor produces a load signal. An input device produces a request signal for actuating the second propulsion system. An electronic control mechanism is electrically connected to the input device and the load sensor for coordinating the various sensors and inputs. The control mechanism commands the second propulsion system in response to the load signal and the request signal such that the trailer is propelled in a controlled manner relative to the tractor.

Development of Methods for Analysis and Optimization of Complex Jet Engine Systems

Abstract: This thesis describes the development of GESTPAN (GEneral Stationary and Transient Propulsion ANalysis), a generalized system for the design, steady-state and transient simulation of gas turbine systems. Some of the main achievements in the thesis are related to the development of new algorithms or integration of existing numerics tailored to simplify the structure and use of generalized gas turbine simulation systems. In particular, a method for performing system design utilizing the analysis equations, i.e. an inverse design method, has been developed. Furthermore, attention is drawn to a number of advantages of using an implicit high order differential algebraic system solver for transient gas turbine system analysis. The simulation studies carried out with the GESTPAN system have focused on the performance optimization of the Selective Bleed variable cycle engine. In particular, a method for controlling the engine during mode transition was developed. Work with the implementation of a hybridized optimization method suitable for mission optimization of variable cycle engines is also described. The method couples the cycle selection and the control optimization of the engine variable geometry. Simulations performed with the method indicate that previously published designs of the Selective Bleed Variable cycle engine can be downsized considerably. Early work carried out in the research project concentrated on developing a method for optimizing the performance of variable geometry compressors integrated in gas turbine systems. Although the method was limited to subsonic operation of compressors, it was successfully used to simulate the core driven fan stage of the double bypass variable cycle engine.

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.

Hybrid electric vehicle with limited operation strategy

Abstract: A hybrid electric vehicle 10 having a propulsion system 12 which includes an internal combustion engine 14, a generator/motor 16 and an electric motor or a “traction inverter module” 18 which cooperatively provide power to the drive train 28 of vehicle 10. Vehicle 10 includes a controller 44 which is effective to detect whether any faults are present within any of the torque providing subsystems (e.g., in engine 14, generator/motor 16 and/or motor 18), and if one or more faults is. present, to provide a limited operation strategy which allows the vehicle to be driveable by use of the remaining operational subsystem(s).