Elektrische Antriebe für die Raumfahrt

Electric Propulsion for Space Flight This article describes electric rocket motors for satellites, probes and manned spacecraft based on principles used for material processing, too. The need for high exhaust velocities is explained and the limitations of conventional chemical thrusters are pointed out. Two important electric propulsion technologies, arcjet thrusters and gridded ion thrusters, together with their applications are described. Both types are currently successfully operated in space. Finally, a hybrid engine using an arcjet thruster and propellant heating by radiofrequency power is introduced. This concept is a potential solution for the propulsion demands of a future piloted mission to Mars.     

Recovery of lunar surface access module residual and reserve propellants

The vision for space exploration calls for human exploration of the lunar surface in the 2020 timeframe. Sustained human exploration of the lunar surface will require supply, storage, and distribution of consumables for a variety of mission elements. These elements include propulsion systems for ascent and descent stages, life support for habitats and extra-vehicular activity, and reactants for power systems. NASA KSC has been tasked to develop technologies and strategies for consumables transfer for lunar exploration as part of the exploration technology development program. This paper will investigate details of operational concepts to scavenge residual propellants from the lunar descent propulsion system. Predictions on the mass of residuals and reserves are made. Estimates of heat transfer and boil-off rates are calculated and transient tank thermodynamic issues post-engine cutoff are modeled. Recovery and storage options, including cryogenic liquid, vapor and water are discussed, and possible reuse of LSAM assets is presented.     

中国液体火箭发动机如何进入21世纪

液体火箭发动机是宇航推进家族的重要成员,将会成为下一个历史时期使有效载荷达到第一宇宙速度的唯一推进手段,是制约航天发展速度的最关键因素。发展运载系统,动力必须先行。中国在21世纪初必须推出能与世界先进国家相当的大型运载火箭。这些火箭不能建立在用原有的发动机增加数量以加大推力的基础上,必须研制单台推力更大、更先进、无污染的新型发动机,同时还需开展火箭航天飞机及其发动机使用的气动塞式喷管的预先研究,以火箭航天飞机为突破口,赶上世界先进水平。     

考虑发动机推力影响的机翼颤振分析

发动机安装在机翼上时,其推力具有典型的随动特征,并对机翼颤振产生重要影响.基于有限元分析软件MSC/Nastran的DMAP开发,提出了一种考虑发动机推力和几何非线性影响的机翼颤振分析方法.作为验证,分析了推力对某高空长航时飞行器机翼颤振速度的影响,与已有结果吻合良好.对一带有两个发动机的复杂机翼结构进行了结构建模和颤振分析,重点分析了推力大小及作用位置对颤振速度的影响.结果表明,发动机的推力效应在颤振分析中是不应忽略的.     

High speed propulsion: Performance advantage of advanced materials

High-speed air breathing propulsion systems have many attractive military and civil applications. The high propulsive efficiency of these systems allows the exploitation of speed, distance, and bigger payloads, or any combination of the three. The severe operating conditions of these systems require particular attention to overall thermal management of the engine/air-frame. Fuel-cooling the engine structure is a viable way of maintaining thermal balance over a range of flight conditions. Air Force applications have focused on using endothermic hydrocarbon fuels to address this issue because of their compatibility with the military operations. Recent ground tests of scramjet engines have demonstrated adequate performance utilizing state-of-the-art technology in materials. This progress has paved the way for an expendable flight test vehicle in the near future. In order to take full advantage of the capabilities of this propulsion system, advances in fuel-cooled structures, high temperature un-cooled materials, and increased heat capacity of hydrocarbon fuels will be needed to enable expendable systems to reach higher Mach numbers. An additional benefit would be realized in future reusable systems.     

Multidisciplinary approach to materials selection for bipropellant thrusters using ablative and radiative cooling

Reduction of costs is a main consideration in every space mission, and propulsion system is an important subsystem of those missions where orbital maneuvers are considered. Lighter propulsions with higher performance are necessary to reduce the mission costs. Bipropellant propulsions have been widely used in launch vehicles and upper-stages as well as deorbit modules because of better performances in comparison with other propulsion systems. Unfortunately heat transfer and thermal control limit bipropellant propulsion performance and maximum performance cannot be achieved. Well-known cooling methods such as regenerative and film cooling increase the cost using extra equipment and high temperature materials. In this paper, a new approach for cooling is presented based on combined ablative and radiative cooling. Governing equations are derived for two or three layers of thermal protection system (TPS) to optimize the TPS mass. The first layer is used as an ablative layer to control the temperature where the second and third layers are used as an insulator to control the heat fluxes. Proposed cooling method has been applied for two real bipropellant thrusters. According to the results, the presented algorithm can suitably predict the heat fluxes and satisfy the wall temperature constraint. Then, the algorithm has been used to minimize the wall temperatures as low as possible and replace high temperature materials (platinum alloy) with common materials (composite or steel). It is shown that selection of TPS materials affects the TPS mass and Isp simultaneously, but conversely. Best solution should be derived by trading off between structure temperature (cost), Isp (performance), and TPS thicknesses (geometry). Multidisciplinary approach to TPS and structure material selection of a bipropellant thruster is presented for a case study. It has been shown that mass and performance penalties of using TPS are acceptable, considering the advantages of using steel alloy instead of platinum alloy.     

主机对中姿态参数的近似算法

利用3个非共线设置的特征光标和单个CCD相机来获取空间物体的三维信息,采用广义欧拉角（布利恩角）来描述主机的对中姿态。基于小孔成像,建立主机与轴系之间的简化数学模型,推导了对中姿态参数的一种新的近似解析算法,建立了主机对中姿态方程,并叙述了姿态方程在主机对中姿态控制中的作用。最后,对该近似算法的误差进行仿真研究。     

深空电推进阻滞势分析仪探测方法研究

随着人类对外太空环境认识的不断深入,电推进已成为通向未知空间领域的重要技术途径。空间电推进对航天器防护结构、能源系统、敏感有效载荷系统均产生不同影响。介绍了基于阻滞势分析仪的电推进等离子体参数探测方法,通过阻滞势分析仪研制和相应的地面模拟实验,计算得到了推力器40cm处的粒子能量、离子密度和离子温度等参数,相关研究为我国电推进航天器的深空应用和发展提供技术参考。     

Multicompartment Tubular Micromotors Toward Enhanced Localized Active Delivery

A tubular micromotor with spatially resolved compartments is presented toward efficient site-specific cargo delivery, with a back-end zinc (Zn) propellant engine segment and an upfront cargo-loaded gelatin segment further protected by a pH-responsive cap. The multicompartment micromotors display strong gastric-powered propulsion with tunable lifetime depending on the Zn segment length. Such propulsion significantly enhances the motor distribution and retention in the gastric tissues, by pushing and impinging the front-end cargo segment onto the stomach wall. Once the micromotor penetrates the gastric mucosa (pH ≥ 6.0), its pH-responsive cap dissolves, promoting the autonomous localized cargo release. The fabrication process, physicochemical properties, and propulsion behavior are systematically tested and discussed. Using a mouse model, the multicompartment motors, loaded with a model cargo, demonstrate a homogeneous cargo distribution along with approximately four-fold enhanced retention in the gastric lining compared to monocompartment motors, while showing no apparent toxicity. Therapeutic payloads can also be loaded into the pH-responsive cap, in addition to the gelatin-based compartment, leading to concurrent delivery and sequential release of dual cargos toward combinatorial therapy. Overall, this multicompartment micromotor system provides unique features and advantages that will further advance the development of synthetic micromotors for active transport and localized delivery of biomedical cargos.     

空间电推进技术及应用新进展

在系统调研2000年以来国内外空间电推进技术及应用进展的基础上,详细介绍了电推进在GEO卫星位置保持和轨道转移、深空探测主推进、科学观测和试验等领域的空间应用情况,分别给出了离子电推进、霍尔电推进和其他电推进类型的新研产品及主要性能,对电推进新技术发展情况进行了概要性的介绍,最后对空间电推进技术及应用的新进展给出了简要总结和评述。     

Multidisciplinary design and optimization of an air launched satellite launch vehicle using a hybrid heuristic search algorithm

A multidisciplinary design and optimization strategy for a multistage air launched satellite launch vehicle comprising of a solid propulsion system to low earth orbit with the implementation of a hybrid heuristic search algorithm is proposed in this article. The proposed approach integrated the search properties of a genetic algorithm and simulated annealing, thus achieving an optimal solution while satisfying the design objectives and performance constraints. The genetic algorithm identified the feasible region of solutions and simulated annealing exploited the identified feasible region in search of optimality. The proposed methodology coupled with design space reduction allows the designer to explore promising regions of optimality. Modules for mass properties, propulsion characteristics, aerodynamics, and flight dynamics are integrated to produce a high-fidelity model of the vehicle. The objective of this article is to develop a design strategy that more efficiently and effectively facilitates multidisciplinary design analysis and optimization for an air launched satellite launch vehicle.     

A hybrid electronic-density-functional/molecular-dynamics simulation scheme for multiscale simulation of materials on parallel computers: applications to silicon and alumina

In hybrid electronic-density-functional/molecular-dynamics schemes, a total system is partitioned in real space into the quantum-mechanical (QM) region treated by the electronic-density-functional theory and the molecular dynamics (MD) region in which atoms are interacting through the empirical inter-atomic potential. In the former hybrid scheme [Ogata et al. Comput. Phys. Commun. 149 (2002) 30], appropriate selection of QM atoms for seamless coupling between the QM and MD regions is limited in Si systems, and applications of the scheme to other materials are difficult. Novel hybrid scheme that is free from the limitation and applicable to both Si and alumina systems, is presented.     

Integrated gas analyzer for complete monitoring of turbine engine test cells

Fourier transform infrared (FT-IR) spectroscopy is proving to be reliable and economical for the quantification of many gas-phase species during testing and development of gas turbine engines in ground-based facilities such as sea-level test cells and altitude test cells. FT-IR measurement applications include engine-generated exhaust gases, facility air provided as input to engines, and ambient air in and around test cells. Potentially, the traditionally used assembly of many gas-specific single gas analyzers will be eliminated. However, the quest for a single instrument capable of complete gas-phase monitoring at turbine engine test cells has previously suffered since the FT-IR method cannot measure infrared-inactive oxygen molecules, a key operational gas to both air-breathing propulsion systems and test cell personnel. To further the quest, the FT-IR sensor used for the measurements presented in this article was modified by integration of a miniature, solid-state electrochemical oxygen sensor. Embedded in the FT-IR unit at a location near the long-effective-optical-path-length gas sampling cell, the amperometric oxygen sensor provides simultaneous, complementary information to the wealth of spectroscopic data provided by the FT-IR method.     

Power and Transport Systems for Space Applications, Utilizing the MHD Method of Energy Conversion

The possibility of developing power and transport systems for space applications is examined. It is suggested to use an MHD generator utilizing inhomogeneous gas-plasma flows of inert gas as the source of electric energy in such systems. The plasma of the current layers may be in the state of frozen ionization, when the degree of ionization exceeds the equilibrium level thereby providing for an effective MHD interaction with the enthalpy extraction coefficient of 0.4 and adiabatic efficiency of 0.8. Such a plasma is stable with respect to dissipative instabilities (ionization and overheating) and retains its positive properties at a stagnation pressure of the order of 1 MPa. The estimation of the mass-and-size characteristics of a closed-cycle solar MHD facility for space applications reveals that the specific power of the facility may amount to 500 W/kg. It is suggested that the propulsion unit should be provided by an electric rocket engine on the basis of an MHD accelerator, with the working medium provided by a nonuniform gas-plasma flow in which azimuthal plasma rings (T-layers) are inductively connected to the electric energy source. In a flow with T-layers, an efflux velocity of the order of 40 km/s is attained. With a mass flow rate of 50 g/s, the engine may develop a propulsive force of 2000 N.     

Ein Konzept zur Wirkungsgradoptimierung von Einzylinder-Dieselgeneratoren mittels Optimalsteuerung und Extremum-Seeking

In this contribution the problem of maximizing the efficiency of a hybrid power unit at a specified output power level by optimizing the generator current trajectory as well as the design variables that can be chosen during the machine design process is investigated. The concept is demonstrated based on a hybrid single-cylinder diesel engine that is coupled to an electric generator. By developing a model of the system and using open-loop optimal control the optimal operating strategy and the optimal machine design are determined. Besides that, the problems occurring in the application of this strategy to a test rig are discussed. For this purpose, a model-free real-time optimization concept based on extremum seeking control is presented. The effectiveness of both the model-based and the model-free concept are demonstrated by simulation and experimental results.     

船舶主机气囊隔振技术对中控制策略研究

针对气囊隔振器应用于船舶主机低频隔振面临的如何保证轴系对中精度技术难题,开展其对中控制策略研究。建立了对中状态响应特性分析模型,为解决该分析模型计算输入参数难以精确获取的问题,提出一种伪灵敏度分析方法。基于控制对象伪灵敏度矩阵,研究出可行的对中控制策略。应用该控制策略可使得控制系统在多目标、强耦合条件下,以良好的动态工作性能实现高精度对中控制,并保持装置承载力的均匀分配。     

Development of Advanced Actuators Using Shape Memory Alloys and Electrorheological Fluids

Actuators are used to perform a variety of functions in almost every type of electromechanical system, ``smart' device, and instrument. Increasingly, in many applications, actuators need to achieve reduced size, mass, power consumption, and cost. Examples of industries that demand novel, miniature, and powerful actuators are medicine, biotechnology, information technology, space, manufacturing, entertainment, military, and micro- and nanotechnology. Conventional actuators such as DC motors, pneumatic motors, and hydraulic motors are energy-wasting, large-volume, and heavy-mass actuation systems. Novel design methodologies, materials, and paradigms are currently needed in order to develop such lightweight and powerful actuation systems. In this paper we present the development of two novel, compact, and powerful smart material-based advanced actuators. The first motor is a shape memory alloy (SMA) bundle actuator, and the second is a hybrid concept based on electrorheological fluids (ERFs) and electromagnetic components. A detailed review of the state of the art in SMA- and ERF-based actuators is also presented.     

A new hybrid meta-heuristic algorithm for optimal design of large-scale dome structures

In this article a hybrid algorithm based on a vibrating particles system (VPS) algorithm, multi-design variable configuration (Multi-DVC) cascade optimization, and an upper bound strategy (UBS) is presented for global optimization of large-scale dome truss structures. The new algorithm is called MDVC-UVPS in which the VPS algorithm acts as the main engine of the algorithm. The VPS algorithm is one of the most recent multi-agent meta-heuristic algorithms mimicking the mechanisms of damped free vibration of single degree of freedom systems. In order to handle a large number of variables, cascade sizing optimization utilizing a series of DVCs is used. Moreover, the UBS is utilized to reduce the computational time. Various dome truss examples are studied to demonstrate the effectiveness and robustness of the proposed method, as compared to some existing structural optimization techniques. The results indicate that the MDVC-UVPS technique is a powerful search and optimization method for optimizing structural engineering problems.     

激光推进技术标准体系建设研究

本文总结了激光推进技术的主要特点和未来前景,梳理了当前技术领域中存在的问题,论述了建立激光推进技术标准体系的作用和意义。针对需求分析,初步构建了激光推进技术标准体系框架,对标准体系的主要内容进行了概括和分析,提出了建立我国激光推进技术标准体系的设想。     

Magnetic levitation and propulsion, 1975

A status report on progress toward the development of a magnetic levitation and propulsion system for mass transportation is presented. It summarizes important results and provides a bibliography for further study. Emphasis is placed on various aspects of different magnetic structures which have been proposed for this application.