Propulsion Technology Research Articles

Design and implementation of low-power low-cost quasi steady-state magnetoplasmadynamic propulsion using Ar-He and N<SUB align="right">2-He gas mixtures

Current miniature plasma propulsion technologies use ion or Hall propulsion to provide thrust for miniature satellites. The problem with ion and Hall thrusters is the low thrust-to-power ratio (30 ...

A review on the large-scale shipboard energy storage systems

Energy storage system is an essential equipment in ships, which can supply various kinds of shipboard loads. With the maturity of electric propulsion technology, all-electric ships have become the main trend of future ship design. In this context, the energy storage system will be responsible for multiple types of ship loads, instead of mainly responsible for auxiliary loads in the past, especially acting as a part of the ship’s power system and cooperating with ship’s main/auxiliary engines to improve the economic/environmental characteristics of ships. The change of role accelerates the integration of large-scale energy storage systems into ships, bringing a series of issues such as energy storage system state estimation, energy management, and optimization planning. This paper first classifies the current energy storage technologies, then introduces the structure of typical all-electric ships and points out the application scenarios of energy storage systems, and finally proposes several technical problems that need to be resolved after the large-capacity energy storage systems are connected to ships, namely : Distributed control of ship energy storage system, adaptive planning and optimization of ship energy storage system, and state estimation of ship energy storage system. This research has clarified the future roadmap for large-scale energy storage integration into electrified ships.

Transient Test and AC Loss Study of a Cryogenic Propulsion Unit for All Electric Aircraft

This paper reports a pioneering demonstration platform of a cryogenic propulsion unit at liquid nitrogen temperature. A high temperature superconducting (HTS) machine is connected with a cryogenic power rectifier in a generator mode to prove the feasibility of a cryogenic propulsion unit for electric aircraft propulsion applications. Machine operation was carried out with a special focus on the total heat dissipation inside the HTS AC windings. Different types of 2G HTS tapes were tested to provided data for stator coils’ design. The transient operation was carried out to represent a short-circuit failure in one of the power electronic devices. The test shows AC loss performance of the HTS windings using calorimetric method during the short circuit event, indicating the importance of developing protection schemes for the cryogenic propulsion units to prevent damage to the HTS components. The paper provides initial insights into the interaction between superconducting machines and cryogenic power electronics within a cryogenic propulsion unit. It is an important first step to understand and further develop cryogenic propulsion technology for future electric aircraft.

Scenario Development for Wind Propulsion Technology Adoption: A Theoretical Model for Agent-Based Modeling

Scenario Development for Wind Propulsion Technology Adoption: A Theoretical Model for Agent-Based Modeling

Practical Optimization of Low-Thrust Minimum-Time Orbital Rendezvous in Sun-Synchronous Orbits

High-specific-impulse electric propulsion technology is promising for future space robotic debris removal in sun-synchronous orbits. Such a prospect involves solving a class of challenging problems of low-thrust orbital rendezvous between an active spacecraft and a free-flying debris. This study focuses on computing optimal low-thrust minimum-time many-revolution trajectories, considering the effects of the Earth oblateness perturbations and null thrust in Earth shadow. Firstly, a set of mean-element orbital dynamic equations of a chaser (spacecraft) and a target (debris) are derived by using the orbital averaging technique, and specifically a slow-changing state of the mean longitude difference is proposed to accommodate to the rendezvous problem. Subsequently, the corresponding optimal control problem is formulated based on the mean elements and their associated costate variables in terms of Pontryagin’s maximum principle, and a practical optimization procedure is adopted to find the specific initial costate variables, wherein the necessary conditions of the optimal solutions are all satisfied. Afterwards, the optimal control profile obtained in mean elements is then mapped into the counterpart that is employed by the osculating orbital dynamics. A simple correction strategy about the initialization of the mean elements, specifically the differential mean true longitude, is suggested, which is capable of minimizing the terminal orbital rendezvous errors for propagating orbital dynamics expressed by both mean and osculating elements. Finally, numerical examples are presented, and specifically, the terminal orbital rendezvous accuracy is verified by solving hundreds of rendezvous problems, demonstrating the effectiveness of the optimization method proposed in this article.

Development and Innovative Design Research of Underwater Bionic Fish Products under Hybrid Propulsion Technology

For a long time, underwater robot has been used as a scientific research tool and a teaching platform, but the real application products have not been well explored. The successful case of UAV gives underwater robot a higher expectation. How to apply underwater robot and enter the market has become a hot spot of underwater robot research at present. This paper mainly introduces a bionic fish‐shaped robot, redefines underwater robot with innovative thinking, determines product functions from the perspective of the market, and develops product functions and designs and realizes the structure of each part according to the existing scientific research experience. Main innovation points of this design are to adopt the way of the hybrid propulsion for underwater robot movement, through the form of a hybrid propulsion and long range and the contradiction between the rapid maneuver, at the same time of umbilical cord cable, using float design improvement, and through the highly integrated ground station for the system operation control.

Feasibility analysis of an innovative naval on-board power-train system with hydrogen- based PEMFC technology

The maritime transportation sector is one of the main contributors to global emissions of greenhouse gases (GHGs), volatile organic compounds (VOCs), particulate matter (PM), hazardous air pollutants, NOX and SOX. In particular, it is estimated that the CO2 emissions in this sector are about 1 Gt every year. The International Maritime Organization (IMO) adopted stringent emission limits in its Tier III regulation, most notably on NOX and SOX emissions and pledged to reach a reduction in greenhouse gas (GHG) emissions from international shipments by at least 50% by the year 2050, compared to 2008 emissions. For emission control areas (ECAs) these requirements are particularly strict and will be difficult to meet with traditional diesel engines and bunker fuels. Therefore, ship owners need to adopt solutions to bring emissions within these and other future limits by means of environmentally friendly fuels and high efficiency propulsion technologies. In this context, hydrogen and fuel cells play a crucial role, thanks to their low criteria pollutant and GHG emission. This paper presents a techno-economic feasibility study for replacing the conventional diesel engine powertrain, usually employed in Ro-Pax ferries, with an innovative system based on polymer electrolyte membrane fuel cell (PEMFC) technology. The ferry is actually powered by four diesel engines, which deliver a total output of 37.8 MW. The ferry also has two auxiliary engines which give an output of 4.0 MW and also two 2.0 MW bow thrusters for its manoeuvring. The energy analysis has allowed to define the hydrogen consumption for each cruise, as well as the optimal size of the innovative propulsion system. In particular, The PEMFC powertrain is sized at the same maximum power output as the main diesel engine and, thanks to the modular architecture of fuel cells and their flexible performance at partial load, the auxiliary engines are not contemplated. Moreover, in order to identify the best solution in terms of ship’s weight and space requirements, two hydrogen storage solutions based on compressed hydrogen technology and liquefied hydrogen technology, have been analyzed and compared. The economic assessment has been carried out by estimating the CAPEX and OPEX for each H2 storage technology by considering short-term, mid-term and long-term scenarios (from 2020 to 2050).

Experimental research on the performance of a rotating detonation combustor with a turbine guide vane

Rotating detonation engines (RDEs) have received significant attention from industry and academia alike, owing to their numerous advantages, such as pressure gain combustion, high operation frequency, and near-constant thrust output. Furthermore, there is considerable interest in combining RDEs with gas-turbine engines to further improve their overall system performance. This study examines the propagation characteristics of continuous rotating detonation waves (CRDWs) with a turbine guide vane (TGV). We develop an experimental model of a hydrogen–air rotating detonation combustor integrated with a TGV section and record the high-frequency pressure oscillations and static pressure upstream and downstream of the TGV section. The experimental results indicate that: the interactions between CRDW and the turbine blade cause the reflected shock propagating backwards to the combustor. Both pressure oscillation amplitude and static pressure decline at downstream of TGV. Notably, the pressure oscillation attenuation by the TGV is influenced by the direction of CRDW propagation. When the CRDW propagation direction and the flow path direction of the guide vane are opposite to each other, the pressure oscillation attenuation increases. The findings obtained herein provide benchmark data that help improve the fundamental understanding of CRDW and TGV interaction, and can be used to develop detonation-based propulsion technology.

Physics of E × B discharges relevant to plasma propulsion and similar technologies

This paper provides perspectives on recent progress in understanding the physics of devices in which the external magnetic field is applied perpendicular to the discharge current. This configuration generates a strong electric field that acts to accelerate ions. The many applications of this set up include generation of thrust for spacecraft propulsion and separation of species in plasma mass separation devices. These “E × B” plasmas are subject to plasma–wall interaction effects and to various micro- and macroinstabilities. In many devices we also observe the emergence of anomalous transport. This perspective presents the current understanding of the physics of these phenomena and state-of-the-art computational results, identifies critical questions, and suggests directions for future research.

Comparative study of the energy efficiency of diesel and hybrid powered light aircraft

In recent times many research efforts are aimed at the development of aircraft hybrid propulsion technology as a means to minimize the aircraft environmental impact. The objective is to provide an additional assessment of the energy efficiency of the hybrid powered light aircraft in comparison with current state of the art Diesel powered aircraft. Typical 4-seat propeller airplane is chosen as a prototype and its flight performance model is created using open source data. The comparison is performed for a realistic flight profile including the power demands for go-around and flight to alternate destination airport. Parallel hybrid architecture is considered. A parametric study with variation of the mass, efficiency and energy capacity parameters of the hybrid power train is performed in order to determine the parameter regions where the hybrid power train has advantage over the Diesel one. The present study is based on the previous experience of the authors in assessing the energy efficiency of alternative power sources for the aviation.

Stabilization of first integrals in optimal control problem

The paper considers methods for solving the variational problem of implementing control that stabilizes the optimal movement of the rocket in gravitational fields, finding the most accurate trajectories, and applying the results to solve various practical problems of flight dynamics. The relevance of the study of these problems is due to the fact that space guidance and tracking of the object’s trajectory during the entire flight is the most important basis for a successful space maneuver of ships, satellites, and missiles. Building and implementing in practice the laws of Autonomous guidance in application to modern types of propulsion technology is an acute unsolved problem today, which depends on the ability of aircraft engines to produce the necessary thrust for flight. It takes into account the fact that in reality the object does not fly along the specified trajectory, but has a certain deviation due to inaccuracies in the parameters of the flight model and the propulsion system. Therefore, it is necessary to set the stabilization problem in order to find optimal control conditions. The problems of stabilization and traffic control are important both from a theoretical point of view and because of numerous technical applications. From a theoretical point of view, these problems are important primarily because they relate to complex problems of mechanics, and each time they require new approaches and methods for their solution. In this case, the nature of the problem of motion stabilization depends significantly on the additional conditions that are imposed on the dynamic system.

Power efficiency estimation of an inductive plasma generator using propellant mixtures of oxygen, carbon-dioxide and argon

A promising aspect of inductive plasma generators for space propulsion applications is their electrodeless nature that leads to a high propellant compatibility and opens the door to in-situ resource utilisation propellants. To further develop inductive plasma generators as a space propulsion technology it is important to understand the relationship between system inputs (e.g. input power and propellant material) and system outputs (e.g. power efficiencies) to aid design and control. In this work, methodologies are developed for non-intrusively assessing the inductive coupling from antenna current measurements in terms of the ‘instantaneous ignition power’, the ‘inductive duty cycle’ and the ‘inductive frequency shift’. Experimental results are presented for IPG7, a high-power (up to 180 kW) 5.5-turn helical antenna inductive plasma generator. Potential in-situ resource utilisation materials oxygen and carbon-dioxide, and their respective mixtures with argon, are assessed in terms of their inductive coupling characteristics and resulting power efficiencies. Oxygen is shown to be an attractive propellant material, especially when supplemented with argon. In particular, high thermal efficiency (∼84%) can be achieved at high input powers. A basis is provided for understanding the power efficiencies of an inductive plasma generator in terms of non-intrusive antenna current measurements, to aid power supply sizing and to develop monitoring and control techniques for thruster applications.

Analytical guidance for circular orbit transfers with staging of space propulsion systems

This paper considers the combination of an analytical reference trajectory with linear state feedback control to allow for autonomous guidance and control of a spacecraft for coplanar circle-to-circle transfers with a stage-based propulsion system. Staging of electric propulsion components, such as tanks and thrusters, could allow small spacecraft to achieve high-ΔV capabilities with current propulsion technology. In order to utilize these propulsion systems, further developments in guidance and control of such spacecraft are required due to limitations in computational power and communications. Analytical approximations for low-thrust trajectories could allow for computationally simple guidance and control of autonomous spacecraft for circle-to-circle transfers around large central bodies. Many trajectories have been developed for conventional propulsion systems, based either on their shape or input thrust, and applied for preliminary mission design. A previously developed analytical trajectory is extended to account for the effects of staging propulsion system components. In order to stabilize the trajectory in the presence of disturbances, a linear state feedback control law is designed with linear quadratic regulator methods. Finally, a methodology for determining the correct phasing between the spacecraft and a target object is developed and is practical to implement on power-limited computers. The use of the analytical reference trajectory is simulated on an orbit transfer from low-Earth orbit to geostationary orbit.

Fast initial design of low-thrust multiple gravity-assist three-dimensional trajectories based on the Bezier shape-based method

In deep space exploration, the application of low-thrust propulsion technology and multiple gravity-assist technology will greatly improve the scope of spacecraft exploration but will significantly increase the difficulty of trajectory design. This study proposes a fast initial design method of low-thrust trajectories, which reasonably combines low-thrust propulsion and multiple gravity-assist technology. In this paper, the Bezier shape-based method is combined with the gravity-assist algorithm to obtain a fast algorithm for calculating the low-thrust multiple gravity-assist transfer trajectories. For the design of the Jupiter rendezvous trajectories, the feasibility of the proposed method is proved by comparing several calculation examples with and without gravity assistance. In order to prove the effectiveness of the proposed method, it is compared with the finite Fourier series (FFS) shape-based method. The simulation results show that the proposed method can use shorter computation time to obtain transfer trajectories with smaller velocity increments than the FFS shape-based method. In order to prove the superiority of the proposed method, the results obtained by the proposed method are used as initial values for further optimization of the Gauss pseudospectral method (GPM). The simulation results show that the difference between the performance indexes of the Bezier method and the GPM is only about 2%, while the Bezier method only uses approximately 2% of the computation time of the GPM. The method described in this paper is significant for obtaining a feasible initial solution quickly for a large number of design cases.

Prognostics and Health Management for the Optimization of Marine Hybrid Energy Systems

Decarbonization of marine transport is a key global issue, with the carbon emissions of international shipping projected to increase 23% to 1090 million tonnes by 2035 in comparison to 2015 levels. Optimization of the energy system (especially propulsion system) in these vessels is a complex multi-objective challenge involving economical maintenance, environmental metrics, and energy demand requirements. In this paper, data from instrumented vessels on the River Thames in London, which includes environmental emissions, power demands, journey patterns, and variance in operational patterns from the captain(s) and loading (passenger numbers), is integrated and analyzed through automatic, multi-objective global optimization to create an optimal hybrid propulsion configuration for a hybrid vessel. We propose and analyze a number of computational techniques, both for monitoring and remaining useful lifetime (RUL) estimation of individual energy assets, as well as modeling and optimization of energy use scenarios of a hybrid-powered vessel. Our multi-objective optimization relates to emissions, asset health, and power performance. We show that, irrespective of the battery packs used, our Relevance Vector Machine (RVM) algorithm is able to achieve over 92% accuracy in remaining useful life (RUL) predictions. A k-nearest neighbors algorithm (KNN) is proposed for prognostics of state of charge (SOC) of back-up lead-acid batteries. The classifier achieved an average of 95.5% accuracy in a three-fold cross validation. Utilizing operational data from the vessel, optimal autonomous propulsion strategies are modeled combining the use of battery and diesel engines. The experiment results show that 70% to 80% of fuel saving can be achieved when the diesel engine is operated up to 350 kW. Our methodology has demonstrated the feasibility of combination of artificial intelligence (AI) methods and real world data in decarbonization and optimization of green technologies for maritime propulsion.

A Nuclear Decay Micropropulsion Technology Based on Spontaneous Alpha Decay

Alpha-decay propulsion technology, a microthrust technology based on thin spontaneous-alpha-decay films, is proposed in this paper. A large quantity of decayed alpha particles emitted from the upper surface of thin films would generate thrust statistically. Simulations were executed using the Monte Carlo N-Particle Transport Code (MCNP) to acquire the energy and angular distributions of escaping alpha particles, as well as the key parameters of alpha-decay films. A 22.40-μm 210Po film combined with a 20-μm aluminum film was able to generate an average thrust of 29.5 nN/cm2 in half-life time. The remaining charges and thermal energies of the decay films were considered. Directional-generated alpha particles were simulated to analyze the influence of angular scattering on escaped alpha-particle distributions. Alpha particles with low energy, with large scattering angles, or with large generated angles contributed less to thrust value. With the assumptions of no scattering, constant stopping power, and no range struggling, a set of analytic formulas were derived. Comparisons of the distributions and typical parameters between simulations and the analytic model were conducted. Discrepancies were mostly caused by the three assumptions and were less than 3.7% for thrust and less than 3.9% for the proportion of escaped alpha-particles.

Analysis of the Effects of Electromagnetic Forces on the Relative Motion of a Charged Spacecraft Formation Flying

Abstract In recent years, studying Lorentz’s force has become a possible good means to control the spacecraft to reduce the fuel cost by modulating spacecraft electrostatic charge (magnetic and electric fields). The generation of Lorentz force is finite by the natural magnetic field and the relative velocity of the spacecraft. Therefore, the Lorentz force cannot fully occur from conventional propulsion technologies. Previous studies are concerned with studying Lorentz’s strength in the magnetic field only. In this work, we developed a mathematical model for a new technique establishing a raise in the level of charging in the spacecraft surface that is moving in the Earth’s magnetic field and provided by modulating spacecraft’s electrostatic charge that induces acceleration via the Lorentz force. The acceleration will be used to find the relationship between capacitance and power required to minimize the consumption of control energy used in such cases or to replace the usual control thruster by Lorentz force.

Assessment of near-term fuel screening and qualification needs for nuclear thermal propulsion systems

Nuclear thermal propulsion (NTP) is an in-space propulsion technology capable of both high specific impulse (850–1000 s) and thrust (44–1112 kN), which can help reduce trip times for crewed missions beyond low Earth orbit. NTP technology has been demonstrated during historic programs. Over 20 ground test reactor experiments were performed, which demonstrated the prototypic reactor operations, during the Nuclear Engine for Rocket Vehicle Application (NERVA)/Rover program (1955–1972). Although historical programs have shown that NTP is a viable in-space propulsion technology, developing NTP in modern programs is contingent on the development and qualification of ultrahigh-temperature nuclear fuel technologies that can withstand engine operating conditions. In historical NTP development programs such as NERVA/Rover, prototypic reactor/engine schemes were ground tested to assess the overall system feasibility and to qualify the reactor fuel forms for eventual flight systems. Although this approach is effective to verify fuel performance under prototypic conditions, relying solely on full-scale NTP reactor tests as the pathway for verifying or qualifying fuel is inefficient and cost prohibitive today. Additionally, modern nuclear licensing requirements state that before test reactor approval, reactor components and fuel elements should be qualified via non-nuclear (out-of-pile) and nuclear (in-pile) testing under representative operating conditions. Using this methodology, fuel matures as production scale fabrication methods are established, and as produced fuel performance is demonstrated. This paper provides an overview of historical approaches to NTP fuel performance maturation, including fuel screening and qualification needs, and provides insight for establishing an efficient testing paradigm that can be implemented to rapidly and affordably develop NTP fuel forms for eventual qualification.

Future Directions for Electric Propulsion Research

The research challenges for electric propulsion technologies are examined in the context of s-curve development cycles. It is shown that the need for research is driven both by the application as well as relative maturity of the technology. For flight qualified systems such as moderately-powered Hall thrusters and gridded ion thrusters, there are open questions related to testing fidelity and predictive modeling. For less developed technologies like large-scale electrospray arrays and pulsed inductive thrusters, the challenges include scalability and realizing theoretical performance. Strategies are discussed to address the challenges of both mature and developed technologies. With the aid of targeted numerical and experimental facility effects studies, the application of data-driven analyses, and the development of advanced power systems, many of these hurdles can be overcome in the near future.

Gyroless Spin-Stabilization Controller and Deorbiting Algorithm for CubeSats

CubeSats are becoming increasingly popular in the scientific community. While they provide a whole new range of opportunities for space exploration, they also come with their own challenges. One of the main concerns is the negative impact which they can have in the space debris problem. Commonly lacking from attitude determination and propulsion capabilities, it has been difficult to provide CubeSats with means for active deorbiting. While electric propulsion technology has been emerging for its application in CubeSats, little or no literature is available on methods to enable it to be used for deorbiting purposes, especially within the tight constraints faced by these nanosatellites. We present a new and simple algorithm for CubeSat deorbiting, which proposes the use of novel electric propulsion technology with minimum sensing and actuation capabilities. The algorithm is divided into two stages: a spin-stabilization control; and a deorbiting-phase detection. The spin-stabilization control is inspired by the B-dot controller. It does not require gyroscopes, but only requires magnetometers and magnetorquers as sensors and actuators, respectively. The deorbiting-phase detection is activated once the satellite is spin-stabilized. The algorithm can be easily implementable as it does not require any attitude information other than the orbital information, e.g., from the Global Positioning System receiver, which could be easily installed in CubeSats. The effectiveness of each part of the algorithms is validated through numerical simulations. The proposed algorithms outperform the existing approaches such as deorbiting sails, inflatable structures, and electrodynamic tethers in terms of deorbiting times. Stability and robustness analysis are also provided. The proposed algorithm is ready to be implemented with minimal effort and provides a robust solution to the space junk mitigation efforts.