Abstract: T HE utility and cost effectiveness of small unmanned aerial vehicles (UAVs) has seen a large increase in their use, in both civilian and military applications. Depending on the particular requirements, the aircraft may be powered using a piston-gasoline engine or an electric motor. Electric propulsion appears to be favored as the UAV size diminishes or if stealth, in terms of acoustic signature, is a design requirement. Expressions to estimate the range and endurance of piston propeller and jet aircraft are well established [1,2] (the Breguet equations). Estimates for the range and endurance of electric aircraft are less well established [3,4] and may not be presented in a fashion consistent with that typically employed in the aeronautics community. Consideration of the propulsion system would suggest that equating the power delivered by the battery, accounting for losses due to the propeller, motor, and motor controller, to the power required to overcome drag would yield performance estimates. While this approach is sound, the behavior of a battery and its effective capacity, depending on the current draw (the so-called Peukert effect [5]), should be accounted for; otherwise, significant estimation errors may occur. Consequently, in this Note, expressions are derived to estimate the range and endurance of a battery-powered electric aircraft, accounting for battery discharge behavior. The impact of ignoring the Peukert effect is investigated. Parameters affecting performance are examined.

Abstract: Micro/nano-scale propulsion has attracted considerable recent attention due to its promise for biomedical applications such as targeted drug delivery. In this paper, we report on a new experimental design and theoretical modelling of high-speed fuel-free magnetically-driven propellers which exploit the flexibility of nanowires for propulsion. These readily prepared nanomotors display both high dimensional propulsion velocities (up to ≈ 21 μm s−1) and dimensionless speeds (in body lengths per revolution) when compared with natural microorganisms and other artificial propellers. Their propulsion characteristics are studied theoretically using an elastohydrodynamic model which takes into account the elasticity of the nanowire and its hydrodynamic interaction with the fluid medium. The critical role of flexibility in this mode of propulsion is illustrated by simple physical arguments, and is quantitatively investigated with the help of an asymptotic analysis for small-amplitude swimming. The theoretical predictions are then compared with experimental measurements and we obtain good agreement. Finally, we demonstrate the operation of these nanomotors in a real biological environment (human serum), emphasizing the robustness of their propulsion performance and their promise for biomedical applications.

Abstract: Ship Resistance and Propulsion is dedicated to providing a comprehensive and modern scientific approach to evaluating ship resistance and propulsion. The study of propulsive power enables the size and mass of the propulsion engines to be established and estimates made of the fuel consumption and likely operating costs. This book, written by experts in the field, includes the latest developments from applied research, including those in experimental and CFD techniques, and provides guidance for the practical estimation of ship propulsive power for a range of ship types. This text includes sufficient published standard series data for hull resistance and propeller performance to enable practitioners to make ship power predictions based on material and data contained within the book. A large number of fully worked examples are included to illustrate applications of the data and powering methodologies; these include cargo and container ships, tankers and bulk carriers, ferries, warships, patrol craft, work boats, planing craft and yachts. The book is aimed at a broad readership including practising naval architects and marine engineers, sea-going officers, small craft designers and undergraduate and postgraduate degree students. It should also appeal to others involved in transportation, transport efficiency and eco-logistics, who need to carry out reliable estimates of ship power requirements.

Abstract: Plasma thrusters are challenging the monopoly of chemical thrusters in space propulsion. The specific energy that can be deposited into a plasma beam is orders of magnitude larger than the specific chemical energy of known fuels. Plasma thrusters constitute a vast family of devices ranging from already commercial thrusters to incipient laboratory prototypes. Figures of merit in plasma propulsion are discussed. Plasma processes and conditions differ widely from one thruster to another, with the pre-eminence of magnetized, weakly collisional plasmas. Energy is imparted to the plasma via either energetic electron injection, biased electrodes or electromagnetic irradiation. Plasma acceleration can be electrothermal, electrostatic or electromagnetic. Plasma–wall interaction affects energy deposition and erosion of thruster elements, and thus is central for thruster efficiency and lifetime. Magnetic confinement and magnetic nozzles are present in several devices. Oscillations and turbulent transport are intrinsic to the performances of some thrusters. Several thrusters are selected in order to discuss these relevant plasma phenomena.

Abstract: The performance of the N3-X, a 300 passenger hybrid wing body (HWB) aircraft with turboelectric distributed propulsion (TeDP), has been analyzed to see if it can meet the 70% fuel burn reduction goal of the NASA Subsonic Fixed Wing project for N+3 generation aircraft. The TeDP system utilizes superconducting electric generators, motors and transmission lines to allow the power producing and thrust producing portions of the system to be widely separated. It also allows a small number of large turboshaft engines to drive any number of propulsors. On the N3-X these new degrees of freedom were used to (1) place two large turboshaft engines driving generators in freestream conditions to maximize thermal efficiency and (2) to embed a broad continuous array of 15 motor driven propulsors on the upper surface of the aircraft near the trailing edge. That location maximizes the amount of the boundary layer ingested and thus maximizes propulsive efficiency. The Boeing B777-200LR flying 7500 nm (13890 km) with a cruise speed of Mach 0.84 and an 118100 lb payload was selected as the reference aircraft and mission for this study. In order to distinguish between improvements due to technology and aircraft configuration changes from those due to the propulsion configuration changes, an intermediate configuration was included in this study. In this configuration a pylon mounted, ultra high bypass (UHB) geared turbofan engine with identical propulsion technology was integrated into the same hybrid wing body airframe. That aircraft achieved a 52% reduction in mission fuel burn relative to the reference aircraft. The N3-X was able to achieve a reduction of 70% and 72% (depending on the cooling system) relative to the reference aircraft. The additional 18% - 20% reduction in the mission fuel burn can therefore be attributed to the additional degrees of freedom in the propulsion system configuration afforded by the TeDP system that eliminates nacelle and pylon drag, maximizes boundary layer ingestion (BLI) to reduce inlet drag on the propulsion system, and reduces the wake drag of the vehicle.

Abstract: A synthetic hybrid nanomotor, which combines chemically powered propulsion and magnetically driven locomotion, is described. The new catalytic–magnetic nanomotor consists of a flexible multisegment Pt-Au-Agflex-Ni nanowire, with the Pt-Au and Au-Agflex-Ni portions responsible for the catalytic and magnetic propulsion modes, respectively. The experimental data and theoretical considerations indicate that the hybrid design only minimally compromises the individual propulsion modes. Rapid and convenient switching from the catalytic to the magnetic mode is illustrated. The resulting catalytic–magnetic adaptive nanomotor can address the fuel depletion and salt limitation common to chemically powered motors by switching to magnetic propulsion. Reversal of the motion direction is also achieved upon applying the magnetic field. Such use of two sources to power a hybrid device offers a broader scope of operation and holds considerable promise for designing adaptive nanovehicles that reconfigure their operation in response to environmental changes or unexpected events.

Abstract: A vertical takeoff and landing aircraft having a fuselage with three wings and six synchronously tilt-able propulsion units, each one mounted above, below, or on each half of the aforementioned three wings. The propulsion units are vertical for vertical flight, and horizontal for forward flight. The aircraft wings are placed such that the rear wing is above the middle wing which is placed above the front wing. The placement of each of the propulsion units relative to the center of gravity of the aircraft about the vertical axis inherently assures continued stability in vertical flight mode, following the loss of thrust from any one propulsion unit. The placement of the propulsion units, viewing the aircraft from the front, is such that each propulsion units' thrust wake does not materially disturb the propulsion unit to its rear. When engine driven propellers or rotors are utilized, flapped wing panels are attached outboard of the forward and/or rearward propulsion units to provide yaw control during vertical flight.

Abstract: Gas turbine engines will still represent a key technology in the next 20-year energy scenarios, either in stand-alone applications or in combination with other power generation equipment. This book intends in fact to provide an updated picture as well as a perspective vision of some of the major improvements that characterize the gas turbine technology in different applications, from marine and aircraft propulsion to industrial and stationary power generation. Therefore, the target audience for it involves design, analyst, materials and maintenance engineers. Also manufacturers, researchers and scientists will benefit from the timely and accurate information provided in this volume. The book is organized into five main sections including 21 chapters overall: (I) Aero and Marine Gas Turbines, (II) Gas Turbine Systems, (III) Heat Transfer, (IV) Combustion and (V) Materials and Fabrication.

Abstract: Rotating detonation engines (RDE’s) represent an alternative to the extensively studied pulse detonation engines (PDE’s) for obtaining propulsion from the high efficiency detonation cycle. Since it has received considerably less attention, the general flow-field and effect of parameters such as stagnation conditions, combustion chamber sizing, and fuel mixture on specific impulse are less well understood than for PDE’s. In this paper we use a model developed previously for doing time-accurate calculations of RDE’s in two and three dimensions to examine the effect of different engine sizing parameters on mass flow rate, performance, and thrust. Specific sizing parameters that are discussed are area ratio of micro-injectors to head-end wall, combustion chamber diameter and length. Additionally, several three-dimensional simulations for small combustion chambers with different thicknesses are shown. Results indicate that for many of these parameters, the characteristics of the engine scale in predictable ways for high plenum pressures. At lower plenum pressures, the results are more difficult to interpret. Specific impulses varied from 3300 s (low-pressure, large chamber length) to 5500 s.

Abstract: A Turboelectric Distributed Propulsion (TeDP) system differs from other propulsion systems by the use of electrical power to transmit power from the turbine to the fan. Electrical power can be efficiently transmitted over longer distances and with complex topologies. Also the use of power inverters allows the generator and motors speeds to be independent of one another. This decoupling allows the aircraft designer to place the core engines and the fans in locations most advantageous for each. The result can be very different installation environments for the different devices. Thus the installation effects on this system can be quite different than conventional turbofans where the fan and core both see the same installed environments. This paper examines a propulsion system consisting of two superconducting generators, each driven by a turboshaft engine located so that their inlets ingest freestream air, superconducting electrical transmission lines, and an array of superconducting motor driven fan positioned across the upper/rear fuselage area of a hybrid wing body aircraft in a continuous nacelle that ingests all of the upper fuselage boundary layer. The effect of ingesting the boundary layer on the design of the system with a range of design pressure ratios is examined. Also the impact of ingesting the boundary layer on off-design performance is examined. The results show that when examining different design fan pressure ratios it is important to recalculate of the boundary layer mass-average Pt and MN up the height for each inlet height during convergence of the design point for each fan design pressure ratio examined. Correct estimation of off-design performance is dependent on the height of the column of air measured from the aircraft surface immediately prior to any external diffusion that will flow through the fan propulsors. The mass-averaged Pt and MN calculated for this column of air determine the Pt and MN seen by the propulsor inlet. Since the height of this column will change as the amount of air passing through the fans change as the propulsion system is throttled, and since the mass-average Pt and MN varies by height, this capture height must be recalculated as the airflow through the propulsor is varied as the off-design performance point is converged.

Abstract: The use of in-wheel motors, often referred to as hub motors, as a source of propulsion for pure electric or hybrid electric vehicles has recently received a lot of attention. Since the motor is housed in the limited space within the wheel rim, it must have a high torque density and efficiency, and survive the rigours of being in-wheel in terms of environmental cycling, ingress, shock and vibration and driver abuse. Finally, to ensure adequate levels of functional safety are met it is essential that failures do not lead to loss of control of the vehicle. This paper presents studies of a fault tolerant concept for the design of in-wheel motors. The study focused on achieving a high torque density and the ability to sustain an adequate level of performance following a failure. A series of failures are simulated and then compared with experimental tests on a demonstrator motor.

Abstract: It has been previously suggested that the generation of coherent vortical structures in the near-wake of a self-propelled vehicle can improve its propulsive efficiency by manipulating the local pressure field and entrainment kinematics. This paper investigates these unsteady mechanisms analytically and in experiments. A self-propelled underwater vehicle is designed with the capability to operate using either steady-jet propulsion or a pulsed-jet mode that features the roll-up of large-scale vortex rings in the near-wake. The flow field is characterized by using a combination of planar laser-induced fluorescence, laser Doppler velocimetry and digital particle-image velocimetry. These tools enable measurement of vortex dynamics and entrainment during propulsion. The concept of vortex added-mass is used to deduce the local pressure field at the jet exit as a function of the shape and motion of the forming vortex rings. The propulsive efficiency of the vehicle is computed with the aid of towing experiments to quantify hydrodynamic drag. Finally, the overall vehicle efficiency is determined by monitoring the electrical power consumed by the vehicle in steady and unsteady propulsion modes. This measurement identifies conditions under which the power required to create flow unsteadiness is offset by the improved vehicle efficiency. The experiments demonstrate that substantial increases in propulsive efficiency, over 50 % greater than the performance of the steady-jet mode, can be achieved by using vortex formation to manipulate the near-wake properties. At higher vehicle speeds, the enhanced performance is sufficient to offset the energy cost of generating flow unsteadiness. An analytical model explains this enhanced performance in terms of the vortex added-mass and entrainment. The results suggest a potential mechanism to further enhance the performance of existing engineered propulsion systems. In addition, the analytical methods described here can be extended to examine more complex propulsion systems such as those of swimming and flying animals, for whom vortex formation is inevitable.

Abstract: Propulsion systems and method for making a propulsion system include additively manufacturing a casing body into a single-piece structure having no bonded or bolted joints. The casing body defines a combustion chamber therein and is at least partially composed of a material useful as a solid rocket fuel and capable of being consumed during combustion. Other embodiments are also described.

Abstract: NASA has set aggressive fuel burn, noise, and emission reduction goals for a new generation (N+3) of aircraft targeting concepts that could be viable in the 2035 timeframe. Several N+3 concepts have been formulated, where the term "N+3" indicate aircraft three generations later than current state-of-the-art aircraft, "N". Dramatic improvements need to be made in the airframe, propulsion systems, mission design, and the air transportation system in order to meet these N+3 goals. The propulsion system is a key element to achieving these goals due to its major role with reducing emissions, fuel burn, and noise. This report provides an in-depth description and assessment of propulsion systems and technologies considered in the N+3 subsonic vehicle concepts. Recommendations for technologies that merit further research and development are presented based upon their impact on the N+3 goals and likelihood of being operational by 2035.

Abstract: Gas Turbine Propulsion Systems in Aerospace & Defense pulls together all of the systems and subsystems associated with gas turbine engines in aircraft and marine warship applications. The subject of engine (fuel) control has undergone major changes in the past 20 years due to the advent of the digital electronic control technology and therefore existing books on the subject are typically out of date with current methods. Gas Turbine Propulsion Systems in Aerospace & Defense discusses the latest technologies in this area; including marine propulsion which is an emerging application area for the technology that involves some interesting modifications to aviation technologies. This book also fits well into the systems engineering focus of the Aerospace Series.Includes chapters on aircraft engine systems functional overview, marine propulsion systems, fuel control and power management systems, engine lubrication and scavenging systems, nacelle and ancillary systems, engine certification, unique engine systems and future developments in gas turbine propulsion systemsIncludes case studies of specific enginesIncludes applications within marine defenceAccompanied by a book companion website featuring full colour images

Abstract: al Mobuliform swimmers are inspiring novel approaches to the design of underwater vehicles. These swimmers, exemplified bymanta rays, present amodel for new classes of efficient, highly maneuverable, autonomous undersea vehicles. To improve our understanding of the unsteady propulsion mechanisms used by these swimmers, we report detailed studies of the performance of robotic swimmers that mimic aspects of the animal propulsive mechanisms. We highlight the importance of the undulatory aspect of producing efficientmanta ray propulsion and show that there is a strong interaction between the propulsive performance and the flexibility of the actuating surfaces.

Abstract: Sustained hypersonic (M>5) atmospheric flight is best performed with a supersonic combustion ramjet (Scramjet). Scramjet-powered flight with durations over 100 seconds (X51) has now been demonstrated. A Scramjet-powered vehicle requires a “boost” to its ramjet takeover (RTO) speed where it can provide adequate acceleration to its cruise speed. All Scramjet powered flights to date have used a solid rocket booster motor that was dropped just before RTO. Although this is practical for demonstration flights, it is unaffordable for an operational vehicle, particularly when the vehicle is to be reused. Reusable hypersonic vehicles require a synergistically integrated self boosting capability. In this paper, we describe the issues such propulsion systems must address and discuss various Aerojet solutions to make them practical.

Abstract: Several characteristics of drag-based paddling propulsion are studied with a simple mechanical model and a measurement technique for mapping three-dimensional flow fields. In drag-based propulsion, the temporal change of the vortex strength is an important parameter in the relationship between vortex formation and thrust generation. Our results indicate that spanwise flow behind the paddling propulsor significantly affects tip vortex development and thrust generation. The distribution of spanwise flow is dependent on the propulsor shape and the Reynolds number. A delta-shaped propulsor generates strong spanwise flow compared with a rectangular propulsor. For the low Reynolds number case, spanwise flow is not as strong as that for the high Reynolds number case. Without sacrificing total impulse, the flexible propulsor can smooth out thrust peaks during sudden stroke motions, which is favorable for avoiding structural failures and stabilizing body motion. We also explored the role of stopping vortex shedding in efficient thrust generation by determining the relationship between stroke angles and total impulses generated by paddling propulsors.

Abstract: Gaseous jets injected into water are typically found in underwater propulsion, and the flow is essentially unsteady and turbulent. Additionally, the high water-to-gas density ratio can result in complicated flow structures; hence it remains a challenging issue to measure the flow structures numerically and experimentally. To investigate the performance of the underwater propulsion, the detailed Navier-Stokes flow computations are utilized in this paper to elucidate the gas-water interactions under the framework of the volume of fluid (VOF) model. Furthermore, the fluid compressibility, viscosity, and energy transfer are taken into consideration. The numerical results and experimental data are compared, showing that phenomena including expansion, bulge, necking/breaking and back-attack are highlighted in the jet process. The resulting analysis indicates that the pressure difference on the rear and front surfaces of the propulsion system can generate an additional thrust. The strong and oscillatory thrust of the underwater propulsion system is caused by the intermittent pulses of the back pressure and the nozzle exit pressure. As a result, the total thrust in underwater propulsion is not only determined by the nozzle geometry but also by the flow structures and associated pressure distributions.

Abstract: Electric ship propulsion systems could be found on marine vessels a century ago. In these early ships, the electrical propulsion system acted as a gearbox, and shipboard power requirements were dwarfed by those of propulsion. While electric propulsion systems later gave way to mechanical drive systems, the past two decades have seen a resurgence in electric ship technology.

Abstract: This paper concerns the design, implementation, and nonlinear velocity-tracking control of a novel magnetic-levitation (maglev) system for magnetically levitated trains. The proposed system uses only one tubular linear induction motor to produce three forces required in a maglev system: propulsion, levitation, and guidance. Classical maglev systems, on the other hand, contain a separate force-generating system to build each of these three forces. Another benefit that the proposed system offers is that there is no need to control the guidance, and particularly, the levitation forces, one of the most challenging tasks in maglev systems. The system always centers the moving part during operation and eliminates the necessity for control of the levitation and guidance forces. However, the propulsion force strongly requires some control efforts because a linear induction motor has nonlinear system dynamics. This paper gives a condensed design guideline based on the mature theory of electromagnetic launchers, particularly the linear induction launcher type. It explains the implementation process, shows experimental test results, and finally, presents a nonlinear partial state-feedback controller for the proposed system.

Abstract: Onboard DC Grid is a novel, new technology which is a further development of utilizing DC links that already exists in all propulsion and thruster drives, accomplishing for usually more than 80% of the electrical power consumption on electric propulsion vessels. This extension means that we keep all the good and well proven products used in today’s electric ships like AC generators, inverter modules, AC motors, etc. The main AC switchboard and transformers are not longer needed. The result is a more flexible power and propulsion system. Further Onboard DC Grid enables a combination of power sources and energy storage. Onboard DC Grid is suitable for vessels with total installed power of up to 20MW and operates at 1000V DC on the main bus. Typical target vessel is Offshore Support Vessels (OSVs), but any other vessel type using low voltage electric distribution would also be in the target range. For DP operation this approach gives several benefits. Firstly, the power network is no longer fixed at 60Hz. This means that an additional freedom of controlling the generator engine speed is present, giving the possibility to run engines efficiently even at 50% loading or lower. Today’s discussion of operating the power plant with open or closed bustie breakers can then be closed. Secondly, use of energy storage gives a possibility to level out the power variations on the engines even if the thruster loads are varying significantly due to vessel movements in bad weather conditions. This does not only contribute to increased fuel saving, but equally important would be the increased DP performance by the fact that the dynamic response of the thrusters would be independent from the engine dynamics. Today each thruster will experience ramp limits in power changes due to limitations in engines, however the energy storage take most of these power variations and hence reduce these limitations to a minimum. To conclude Onboard DC Grid is suited for vessels with total installed power up to about 20MW. It is flexible with respect to use of various power and fuel sources, and it gives clear benefits for vessels operating in DP, with respect to fuel consumption but also with respect to dynamic performance of the thruster system. Click below to:

Abstract: of thrust and thrust efficiency can be obtained from electrohydrodynamic thrusters, etc. In this paper, a simple onedimensional model of an ideal electrohydrodynamic thruster for calculating thrust efficiency and thrust of electrohydrodynamic thrusters is presented. The maximum current that can be achieved for an ideal electrohydrodynamicthrusteratagivenvoltageisalsocalculated.Thisallowsthecalculationofthemaximumthrust that can be obtained from the thruster and the corresponding thrust efficiency. It is shown that, with an increase in the voltage, the maximum thrust and the corresponding thrust efficiency move in opposite directions: the thrust efficiency decreases, while the thrust increases. It is also shown that, at high altitudes, the performance of electrohydrodynamic thrusters (thrust and thrust efficiency) drops very fast; therefore, using electrohydrodynamic thrusters at altitudes greater than 5 km is apparently unrealistic. The model shows that maximum thrust cannot exceed 20–30 N=m 2 at sea level, even at breakdown voltage. The model illuminates the physical limitations of electrohydrodynamic thrusters and provides reasonable estimates of the performance limits of real electrohydrodynamic thrusters.

Abstract: A system includes a first propulsion subsystem and a second propulsion subsystem. The first propulsion subsystem is operable to provide electrical energy to a first communication device when operating in an ON mode. The second propulsion subsystem is operable to provide electrical energy to a second communication device when operating in the ON mode. The first propulsion subsystem and the second propulsion subsystem are controllable in a mode of operation where if one of the first propulsion subsystem or the second propulsion subsystem is controlled to be in an OFF mode, the other of the first propulsion subsystem and the second propulsion subsystem provides electrical energy to the respective first communication device or the second communication device.

Abstract: This paper introduces a new approach to the study of artificial equilibrium points in the circular restricted three-body problem for propulsion systems with continuous and purely radial thrust. The propulsion system is described by means of a general mathematical model that encompasses the behavior of different systems like a solar sail, a magnetic sail and an electric sail. The proposed model is based on the choice of a coefficient related to the propulsion type and a performance parameter that quantifies the system technological complexity. The propulsion system is therefore referred to as generalized sail. The existence of artificial equilibrium points for a generalized sail is investigated. It is shown that three different families of equilibrium points exist, and their characteristic locus is described geometrically by varying the value of the performance parameter. The linear stability of the artificial points is also discussed.