检索结果-内蒙古大学图书馆

54th AIAA/SAE/ASEE Joint propulsion Conference, 2018

作者： Thomas, George L. Culley, Dennis E. Kratz, Jonathan L. Fisher, Kenneth L. Intelligent Control and Autonomy Branch N&R Engineering and Management Services Inc. Parma HeightsOH44130 United States Intelligent Control and Autonomy Branch NASA Glenn Research Center ClevelandOH44135 United States Propulsion Systems Analysis Branch NASA Glenn Research Center ClevelandOH44135 United States

ISBN: (数字)9781624105708

ISBN: (纸本)9781624105708

NASA and a variety of aerospace industry stakeholders are investing in conceptual studies of electrified aircraft, including parallel hybrid electric aircraft such as the Subsonic Ultra Green Aircraft Research (SUGAR) Volt. At this point, little of the work published in the literature has examined the transient behavior of the turbomachinery in these systems. This paper describes a control system built around the hFan, the parallel hybrid electric turbofan engine designed for the SUGAR Volt concept aircraft. This control system is used to show that the hFan, running with its baseline concept of operations, is capable of transient operation throughout the envelope. The design parameters of this controller are varied to assess the amount of operability margin built into the engine design, and whether this margin can be reduced to enable more aggressive designs, that may feature better fuel economy. Further, studies are performed as parameters for the hFan electric motor are varied to determine how the motor impacts the engine’s need for transient operability margin. The studies suggest that the engine may be redesigned with as much as a 3% reduction in high pressure compressor stall margin. It was also demonstrated that appropriate design and control of the electric motor may be able to buy an additional 0.5% stall margin reduction or a turbine inlet temperature reduction of 35 ˚R, as tested at the sea-level static condition. © 2018 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

关键词： Fuel economy

来源：评论

学校读者我要写书评

暂无评论

3d simulations of ion thruster accelerator grid erosion accounting for charge exchange ion space charge 54th

3d simulations of ion thruster accelerator grid erosion acco...

引用

54th AIAA/SAE/ASEE Joint propulsion Conference, 2018

作者： Chaplin, Vernon H. Polk, James E. Katz, Ira Anderson, John R. Williams, George J. Soulas, George C. Yim, John T. NASA Jet Propulsion Laboratory California Institute of Technology Electric Propulsion Group 4800 Oak Grove Dr PasadenaCA91109 United States NASA Jet Propulsion Laboratory California Institute of Technology Propulsion and Materials Engineering Section 4800 Oak Grove Dr PasadenaCA91109 United States NASA Jet Propulsion Laboratory California Institute of Technology Contamination Control Engineering Group 4800 Oak Grove Dr PasadenaCA91109 United States NASA Glenn Research Center Electric Propulsion Systems Branch 21000 Brookpark Rd ClevelandOH44135 United States

ISBN: (数字)9781624105708

ISBN: (纸本)9781624105708

Accelerator (accel) grid sputtering by ions formed through charge-exchange (CEX) reactions between beam ions and residual neutral gas is a critical life-limiting mechanism for gridded ion thrusters. The three-dimensional ion optics code CEX3D is designed to simulate this grid erosion for a single beamlet, with a particular emphasis on non-axisymmetric features such as the "pits and grooves" erosion commonly observed on the accel grid downstream face in two-grid thrusters. The treatment of CEX ions in the code was recently upgraded with a new particle-in-cell (PIC) module to account for the influence of these ions’ space charge on the electrostatic potential downstream of the grids. In order to achieve reasonable computation times while resolving the Debye length near the grids and avoiding gross violations of the Courant-Friedrichs-Lewy (CFL) condition, macroparticle velocities in the PIC calculation are limited through a rescaling procedure that preserves ion trajectories and space charge density. The code accounts for beam divergence, finite momentum transfer in CEX collisions, and radial losses of CEX ions from the beam;these effects are important for determining the CEX ion flux to the accel grid because the calculated potential downstream of the grids can become very flat. The upgraded code has been used to simulate operation of NASA’s Evolutionary Xenon Thruster (NEXT) during the 51 kHr Long Duration Test a selection of results is presented and compared with experimental data. © 2018, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Ion exchange

来源：评论

学校读者我要写书评

暂无评论

Micrometeoroid Events in LISA Pathfinder

arXiv

引用

arXiv 2019年

作者： Thorpe, J.I. Slutsky, J. Baker, John G. Littenberg, Tyson B. Hourihane, Sophie Pagane, Nicole Pokorny, Petr Janches, Diego Armano, M. Audley, H. Auger, G. Baird, J. Bassan, M. Binetruy, P. Born, M. Bortoluzzi, D. Brandt, N. Caleno, M. Cavalleri, A. Cesarini, A. Cruise, A.M. Danzmann, K. de Deus Silva, M. de Rosa, R. Di Fiore, L. Diepholz, I. Dixon, G. Dolesi, R. Dunbar, N. Ferraioli, L. Ferroni, V. Fitzsimons, E.D. Flatscher, R. Freschi, M. Marirrodriga, C. García Gerndt, R. Gesa, L. Gibert, F. Giardini, D. Giusteri, R. Grado, A. Grimani, C. Grzymisch, J. Harrison, I. Heinzel, G. Hewitson, M. Hollington, D. Hoyland, D. Hueller, M. Inchauspé, H. Jennrich, O. Jetzer, P. Johlander, B. Karnesis, N. Kaune, B. Korsakova, N. Killow, C.J. Lobo, J.A. Lloro, I. Liu, L. López-Zaragoza, J.P. Maarschalkerweerd, R. Mance, D. Martín, V. Martin-Polo, L. Martino, J. Martin-Porqueras, F. Madden, S. Mateos, I. McNamara, P.W. Mendes, J. Mendes, L. Nofrarias, M. Paczkowski, S. Perreur-Lloyd, M. Petiteau, A. Pivato, P. Plagnol, E. Prat, P. Ragnit, U. Ramos-Castro, J. Reiche, J. Robertson, D.I. Rozemeijer, H. Rivas, F. Russano, G. Sarra, P. Schleicher, A. Shaul, D. Sopuerta, C.F. Stanga, R. Sumner, T. Texier, D. Trenkel, C. Tröbs, M. Vetrugno, D. Vitale, S. Wanner, G. Ward, H. Wass, P. Wealthy, D. Weber, W.J. Wissel, L. Wittchen, A. Zambotti, A. Zanoni, C. Ziegler, T. Zweifel, P. Barela, P. Cutler, C. Demmons, N. Dunn, C. Girard, M. Hsu, O. Javidnia, S. Li, I. Maghami, P. Marrese-Reading, C. Mehta, J. O’Donnell, J. Romero-Wolf, A. Ziemer, J. Gravitational Astrophysics Lab NASA Goddard Space Flight Center 8800 Greenbelt Road GreenbeltMD20771 United States NASA Marshall Space Flight Center HuntsvilleAL35812 United States University of Michigan Johns Hopkins University Code 674 NASA Goddard Space Flight Center 8800 Greenbelt Road GreenbeltMD20771 United States Catholic University of America European Space Astronomy Centre European Space Agency Villanueva de la Cañada Madrid28692 Spain Albert-Einstein-Institut Max-Planck-Institut für Gravitationsphysik und Leibniz Universität Hannover Callinstraße 38 Hannover30167 Germany APC Univ Paris Diderot CNRS/IN2P3 CEA/lrfu Obs de Paris Sorbonne Paris Cité France High Energy Physics Group Physics Department Imperial College London Blackett Laboratory Prince Consort Road LondonSW7 2BW United Kingdom Dipartimento di Fisica Università di Roma "Tor Vergata" INFN sezione Roma Tor Vergata RomaI-00133 Italy Department of Industrial Engineering University of Trento Trento and Trento Institute for Fundamental Physics and Application INFN via Sommarive 9 38123 Italy Airbus Defence and Space Claude-Dornier-Strasse Immenstaad88090 Germany European Space Technology Centre European Space Agency Keplerlaan 1 Noordwijk2200 AG Netherlands Dipartimento di Fisica Università di Trento and Trento Institute for Fundamental Physics and Application / INFN Povo Trento38123 Italy School of Physics and Astronomy University of Birmingham Birmingham United Kingdom Dipartimento di Fisica Università di Napoli "Federico II" INFN - Sezione di Napoli NapoliI-80126 Italy INFN - Sezione di Napoli NapoliI-80126 Italy Airbus Defence and Space Gunnels Wood Road StevenageHertfordshireSG1 2AS United Kingdom Institut für Geophysik ETH Zürich Sonneggstrasse 5 ZürichCH-8092 Switzerland UK Astronomy Technology Centre Royal Observatory Edinburgh Blackford Hill EdinburghEH9 3HJ United Kingdom Campus UAB Carrer de Can Magrans s/n Cerdanyola del Vallès08193 Spain I

The zodiacal dust complex, a population of dust and small particles that pervades the Solar System, provides important insight into the formation and dynamics of planets, comets, asteroids, and other bodies. Efforts to understand this system have relied on analytic and numerical models anchored by observational data. Much of this observational data is concentrated in the near-Earth regime, where the planet’s gravitational effects mask some of the subtle but important differences between models. Here we present a new set of data obtained using a novel technique: direct measurements of momentum transfer to a spacecraft from individual particle impacts. This technique is made possible by the extreme precision of the instruments flown on the LISA Pathfinder spacecraft, a technology demonstrator for a future space-based gravitational wave observatory that operated near the first Sun-Earth Lagrange point from early 2016 through Summer of 2017. Pathfinder employed a technique known as drag-free control whereby the spacecraft was commanded to maintain a constant position and attitude relative to a free-flying test mass within the instrument. This required rejection of external disturbances, including particle impacts, using a micropropulsion system. Using a simple model of the impacts and knowledge of the control system, we show that it is possible to detect impacts and measure properties such as the transferred momentum (related to the particle’s mass and velocity), direction of travel, and location of impact on the spacecraft. In this paper, we present the results of a systematic search for impacts during 4348 hours of Pathfinder data. We report a total of 54 candidates with momenta ranging from 0.2 µNs to 230 µNs. We furthermore make a comparison of these candidates with models of micrometeoroid populations in the inner solar system including those resulting from Jupiter-family comets, Oort-cloud comets, Hailey-type comets, and Asteroids. We find that our measured popula

关键词： Dust

来源：评论

学校读者我要写书评

暂无评论

Thrust vector control for nuclear thermal rockets 49

Thrust vector control for nuclear thermal rockets

引用

49th AIAA/ASME/SAE/ASEE Joint propulsionConference

作者： Ensworth, Clinton B.F. Propulsion and Control Systems Engineering Branch NASA Glenn Research Center 21000 Brookpark Road MS:86-1 Cleveland OH 44135 United States

ISBN: (数字)9781624102226

ISBN: (纸本)9781624102226

Future space missions may use Nuclear Thermal Rocket (NTR) stages for human and cargo missions to Mars and other destinations. The vehicles are likely to require engine thrust vector control (TVC) to maintain desired flight trajectories. This paper explores requirements and concepts for TVC systems for representative NTR missions. Requirements for TVC systems were derived using 6 degree-of-freedom models of NTR vehicles. Various flight scenarios were evaluated to determine vehicle attitude control needs and to determine the applicability of TVC. Outputs from the models yielded key characteristics including engine gimbal angles, gimbal rates and gimbal actuator power. Additional factors such as engine thrust variability and engine thrust alignment errors were examined for impacts to gimbal requirements. Various technologies are surveyed for TVC systems for the NTR applications. A key factor in technology selection is the unique radiation environment present in NTR stages. Other considerations including mission duration and thermal environments influence the selection of optimal TVC technologies. Candidate technologies are compared to see which technologies, or combinations of technologies best fit the requirements for selected NTR missions. Representative TVC systems are proposed and key properties such as mass and power requirements are defined. The outputs from this effort can be used to refine NTR system sizing models, providing higher fidelity definition for TVC systems for future studies.

关键词： Degrees of freedom (mechanics)

来源：评论

学校读者我要写书评

暂无评论

Performance evaluation of a high bandwidth liquid fuel modulation valve for active combustion control

Performance evaluation of a high bandwidth liquid fuel modul...

引用

50th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

作者： Saus, Joseph R. DeLaat, John C. Chang, Clarence T. Vrnak, Daniel R. NASA Glenn Research Center at Lewis Field Cleveland OH 44135 United States Controls and Dynamics Branch MS 77-1 21000 Brookpark Rd. United States Combustion Branch MS 5-10 21000 Brookpark Rd. United States Propulsion and Control Systems Engineering Branch MS 86-1 21000 Brookpark Rd. United States

At the NASA Glenn Research Center, a characterization rig was designed and constructed for the purpose of evaluating high bandwidth liquid fuel modulation devices to determine their suitability for active combustion control research. Incorporated into the rig's design are features that approximate conditions similar to those that would be encountered by a candidate device if it were installed on an actual combustion research rig. The characterized dynamic performance measures obtained through testing in the rig are planned to be accurate indicators of expected performance in an actual combustion testing environment. To evaluate how well the characterization rig predicts fuel modulator dynamic performance, characterization rig data was compared with performance data for a fuel modulator candidate when the candidate was in operation during combustion testing. Specifically, the nominal and off-nominal performance data for a magnetostrictive-actuated proportional fuel modulation valve is described. Valve performance data were collected with the characterization rig configured to emulate two different combustion rig fuel feed systems. Fuel mass flows and pressures, fuel feed line lengths, and fuel injector orifice size were approximated in the characterization rig. Valve performance data were also collected with the valve modulating the fuel into the two combustor rigs. Comparison of the predicted and actual valve performance data show that when the valve is operated near its design condition the characterization rig can appropriately predict the installed performance of the valve. Improvements to the characterization rig and accompanying modeling activities are underway to more accurately predict performance, especially for the devices under development to modulate fuel into the much smaller fuel injectors anticipated in future lean-burning low-emissions aircraft engine combustors.

关键词： Bandwidth

来源：评论

学校读者我要写书评

暂无评论

A high-fidelity simulation of a generic commercial aircraft engine and controller

A high-fidelity simulation of a generic commercial aircraft ...

引用

46th AIAA/ASME/SAE/ASEE Joint propulsion Conference and Exhibit

作者： May, Ryan D. Csank, Jeffrey Lavelle, Thomas M. Litt, Jonathan S. Guo, Ten-Huei ASRC Aerospace Corp. Cleveland OH 44135 United States N and R Engineering and Management Services Cleveland OH 44130 United States NASA Glenn Research Center Cleveland OH 44135 United States Propulsion and Control Systems Analysis Branch United States Controls and Dynamics Branch United States

A new high-fidelity simulation of a generic 40,000 pound thrust class commercial turbofan engine with a representative controller, known as C-MAPSS40k, has been developed. Based on dynamic flight test data of a highly instrumented engine and previous engine simulations developed at NASA Glenn Research Center, this non-proprietary simulation was created especially for use in the development of new engine control strategies. C-MAPSS40k is a highly detailed, component-level engine model written in MATLAB/Simulink. Because the model is built in Simulink, users have the ability to use any of the MATLAB tools for analysis and control system design. The engine components are modeled in C-code, which is then compiled to allow faster-than-real-time execution. The engine controller is based on common industry architecture and techniques to produce realistic closed-loop transient responses while ensuring that no safety or operability limits are violated. A significant feature not found in other non-proprietary models is the inclusion of transient stall margin debits. These debits provide an accurate accounting of the compressor surge margin, which is critical in the design of an engine controller. This paper discusses the development, characteristics, and capabilities of the C-MAPSS40k simulation.

关键词： controllers

来源：评论

学校读者我要写书评

暂无评论

Rendezvous and docking sensor and effector system design considerations for the lunar lander Altair

Rendezvous and docking sensor and effector system design con...

引用

AIAA Guidance, Navigation, and control Conference

作者： Sullivan, Jacob J. Lee, Allan Y. Grover, Myron R. GN and C Autonomous Flight Systems Branch Johnson Space Center Mail Code EG6 2101 NASA Parkway Houston TX 77058 United States Guidance Navigation and Control Section Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Drive Pasadena CA 91109-8099 United States Guidance Navigation and Control System Altair Lunar Lander Mail Stop 230-104 United States Altair Lunar Lander Systems Engineering Section Jet Propulsion Laboratory 4800 Oak Grove Drive Pasadena CA 91109-8099 United States

ISBN: (纸本)9781600869624

One key function performed by the Guidance, Navigation, and control (GN&C) system of the lunar lander Altair is to rendezvous and dock with the Crew Exploration Vehicle named Orion, in both low Earth orbit and low lunar orbit. The rendezvous and docking process consists of a series of orbital maneuvers and spacecraft attitude controls that successively bring the active vehicle into the vicinity of, and eventually into contact with, the passive vehicle. This paper provides an overview of the rendezvous and docking performance of the Altair GN&C system. To this end, key rendezvous and docking requirements will first be described. These requirements drive the selections of the Altair GN&C sensors, attitude control effectors, and the rendezvous trajectory design. Measurements needed for the rendezvous and docking task will come from the star tracker, inertial measurement unit, docking camera, LIDAR, two-way S-band radiometric ranging data, as well as crew inputs. Measurements from these sensors will be used by the onboard control systems to control well-selected and well-placed Reaction control System (RCS) thrusters to achieve a safe docking. The final contact must be made with the docking axes of the mating vehicles well aligned, both translationally and angularly. Before a high-fidelity simulation test bed is made available, error budgeting is a cost-effective way to assess the docking capability of the Altair and Orion GN&C systems. In docking error budgeting, we first identified all key docking error sources (e.g., attitude control deadbands of mating vehicles, docking sensor measurement error, misalignment between docking sensor and docking mechanism, and others). Results of an error budget study provides the system engineers with a good estimate of whether the GN&C system can achieve the constraints imposed by the docking system. If the docking requirements cannot be met, the relevant error budgets will reveal the source(s) of the problem. Before a high-fidelity

关键词： Budget control

来源：评论

学校读者我要写书评

暂无评论

Time-accurate computations of isolated circular synthetic jets in crossflow

Time-accurate computations of isolated circular synthetic je...

引用

35th AIAA Fluid Dynamics Conference and Exhibit

作者： Rumsey, C.L. Schaeffler, N.W. Milanovic, I.M. Zaman, K.B.M.Q. NASA Langley Research Center Computational Aerosciences Branch Mail Stop 128 Hampton VA 23681-2199 United States NASA Langley Research Center Flow Physics and Control Branch Mail Stop 170 Hampton VA 23681-2199 United States University of Hartford Mechanical Engineering 200 Bloomfield Ave West Hartford CT 06117 United States NASA Glenn Research Center Turbomachinery and Propulsion Systems Division Nozzle Branch Mail Stop 86-7 Cleveland OH 44135 United States

ISBN: (纸本)9781624100598

Results from unsteady Reynolds-averaged Navier-Stokes computations are described for two different synthetic jet flows issuing into a turbulent boundary layer crossflow through a circular orifice. In one case the jet effect is mostly contained within the boundary layer, while in the other case the jet effect extends beyond the boundary layer edge. Both cases have momentum flux ratios less than 2. Several numerical parameters are investigated, and some lessons learned regarding the CFD methods for computing these types of flow fields are outlined. Results in both cases are compared to experiment. © 2005 by the American Institute of Aeronautics and Astronautics, Inc.

关键词： Boundary layers

来源：评论

学校读者我要写书评

暂无评论

AEGIS CRUISER SHIP systems-engineering IMPROVEMENTS

引用

NAVAL ENGINEERS JOURNAL 1987年第3期99卷 181-189页

作者： HOLMES, RW The authorreceived a BSEM degree from Norwich University. After working in the Industrial Engineering Department of Eastman Kodak Company in Rochester NY he went to work for the Navy at the Naval Ship Engineering Center Philadelphia Division (now NAVSSES). He held a variety of assignments in the Heat Power Systems Department and the Machinery Systems Department. He was promoted to a project engineer position in the Gas Turbine Branch and was a project engineer on the DD-963 class propulsion plant land based test. Upon completion of DD-963 class testing and training he transferred to the Naval Sea Support Center Pacific in San Diego. He worked as afield engineer in the Gas Turbine and Control Systems Branch working on a variety of assignments in the fleet primarily aboard DD-963 and FFG-7 class ships. After several years at Naval Sea Support Center Pacific he accepted a position at the Naval Sea Systems Command initially in NAVSEA 05 later transferring to the Aegis Program (PMS 400). He worked on a number of ship systems engineering assignments in the Aegis Cruiser Division where he now serves as the Aegis cruiser technical director. In 1986 he received the Department of Defense Productivity Excellence Award presented by the Honorable Caspar W. Weinberger.

The CG-47 class design process differed from some other ship design processes (such as DD-963, FFG-7, or DDG-51) in that it had to start from a fixed baseline, the DD-963 and DDG-993. Commonality with DD-963 propulsion, electrical, auxiliaries, and hull systems were the design guidelines. The advantage of this philosophy was to get Aegis technology to sea quickly, in a proven hull form. This approach, however, had the disadvantage of fitting more equipment and accommodations into the same hull and inherited DD-963 class problems. This did not necessarily force CG-47 class ships to be built with known deficiencies, however. Through a dedicated ship systems engineering effort, equipment and systems changes and improvements were made and advantage was taken of new technology in the design of USS Ticonderoga (CG-47), and even later follow-on cruisers. This paper describes some of the major HM & E improvements and technical initiatives introduced into CG-47 class ships. The paper presents a synopsis of ten ship systems case studies, followed by three examples of current projects that offer promise. The critical elements of management philosophy are summarized.

关键词： WARSHIPS

来源：评论

学校读者我要写书评

暂无评论

Unattended system for recording machinery transients and for validation of trending algorithms

Unattended system for recording machinery transients and for...

引用

Marine propulsion Technology Conference

作者： Harper, Thurman R. Greenblatt, Jeffrey E. Mazzeo, Andrew J. Propulsion Dynamics Inc. United States Naval Sea Systems Command Hardware/Software Branch Engineering Control Systems Div. United States

A digital data acquisition system was developed for unattended data collection and reduction for use aboard US Navy vessels. Data obtained will be used for performance evaluations, validation of trending algorithms, equipment failure analysis, and generation of operating profiles. The system consists of a shipboard data acquisition unit and a desk-top data reduction processor/report generator. Both units are portable. The shipboard unit operates unattended (except for periodic replacement of the data storage media), is user-configurable, contains a 20-minute uninterruptible power supply, and can monitor up to 64 channels, 32 boolean and 32 analog. Software was developed to support periodic data logging, cumulative signal level versus time profiles, high sample rate look-back for out-of-limit conditions, CRT displays, and interactive system configuration by the user. An application of the system for long terra profiling is described. Copyright © 1986 Society of Automotive Engineers, Inc.

关键词： Report generators

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：