Showing papers on "Propulsion published in 2009"

Modern electric, hybrid electric, and fuel cell vehicles : fundamentals, theory, and design

Abstract: Environmental Impact and History of Modern Transportation Air Pollution Global Warming Petroleum Resources Induced Costs Importance of Different Transportation Development Strategies to Future Oil Supply History of EVs History of HEVs History of Fuel Cell Vehicles Fundamentals of Vehicle Propulsion and Brake General Description of Vehicle Movement Vehicle Resistance Dynamic Equation Tire-Ground Adhesion and Maximum Tractive Effort Power Train Tractive Effort and Vehicle Speed Vehicle Power Plant and Transmission Characteristics Vehicle Performance Operating Fuel Economy Brake Performance Internal Combustion Engines 4S, Spark-Ignited IC Engines 4S, Compression-Ignition IC Engines 2S Engines Wankel Rotary Engines Stirling Engines Gas Turbine Engines Quasi-Isothermal Brayton Cycle Engines Electric Vehicles Configurations of EVs Performance of EVs Tractive Effort in Normal Driving Energy Consumption Hybrid Electric Vehicles Concept of Hybrid Electric Drive Trains Architectures of Hybrid Electric Drive Trains Electric Propulsion Systems DC Motor Drives Induction Motor Drives Permanent Magnetic BLDC Motor Drives SRM Drives Design Principle of Series (Electrical Coupling) Hybrid Electric Drive Train Operation Patterns Control Strategies Design Principles of a Series (Electrical Coupling) Hybrid Drive Train Design Example Parallel (Mechanically Coupled) Hybrid Electric Drive Train Design Drive Train Configuration and Design Objectives Control Strategies Parametric Design of a Drive Train Simulations Design and Control Methodology of Series-Parallel (Torque and Speed Coupling) Hybrid Drive Train Drive Train Configuration Drive Train Control Methodology Drive Train Parameters Design Simulation of an Example Vehicle Design and Control Principles of Plug-In Hybrid Electric Vehicles Statistics of Daily Driving Distance Energy Management Strategy Energy Storage Design Mild Hybrid Electric Drive Train Design Energy Consumed in Braking and Transmission Parallel Mild Hybrid Electric Drive Train Series-Parallel Mild Hybrid Electric Drive Train Peaking Power Sources and Energy Storages Electrochemical Batteries Ultracapacitors Ultra-High-Speed Flywheels Hybridization of Energy Storages Fundamentals of Regenerative Breaking Braking Energy Consumed in Urban Driving Braking Energy versus Vehicle Speed Braking Energy versus Braking Power Braking Power versus Vehicle Speed Braking Energy versus Vehicle Deceleration Rate Braking Energy on Front and Rear Axles Brake System of EV, HEV, and FCV Fuel Cells Operating Principles of Fuel Cells Electrode Potential and Current-Voltage Curve Fuel and Oxidant Consumption Fuel Cell System Characteristics Fuel Cell Technologies Fuel Supply Non-Hydrogen Fuel Cells Fuel Cell Hybrid Electric Drive Train Design Configuration Control Strategy Parametric Design Design Example Design of Series Hybrid Drive Train for Off-Road Vehicles Motion Resistance Tracked Series Hybrid Vehicle Drive Train Architecture Parametric Design of the Drive Train Engine/Generator Power Design Power and Energy Design of Energy Storage Appendices Index

Turboelectric Distributed Propulsion Engine Cycle Analysis for Hybrid-Wing-Body Aircraft

Abstract: Meeting NASA's N+3 goals requires a fundamental shift in approach to aircraft and engine design. Material and design improvements allow higher pressure and higher temperature core engines which improve the thermal efficiency. Propulsive efficiency, the other half of the overall efficiency equation, however, is largely determined by the fan pressure ratio (FPR). Lower FPR increases propulsive efficiency, but also dramatically reduces fan shaft speed through the combination of larger diameter fans and reduced fan tip speed limits. The result is that below an FPR of 1.5 the maximum fan shaft speed makes direct drive turbines problematic. However, it is the low pressure ratio fans that allow the improvement in propulsive efficiency which, along with improvements in thermal efficiency in the core, contributes strongly to meeting the N+3 goals for fuel burn reduction. The lower fan exhaust velocities resulting from lower FPRs are also key to meeting the aircraft noise goals. Adding a gear box to the standard turbofan engine allows acceptable turbine speeds to be maintained. However, development of a 50,000+ hp gearbox required by fans in a large twin engine transport aircraft presents an extreme technical challenge, therefore another approach is needed. This paper presents a propulsion system which transmits power from the turbine to the fan electrically rather than mechanically. Recent and anticipated advances in high temperature superconducting generators, motors, and power lines offer the possibility that such devices can be used to transmit turbine power in aircraft without an excessive weight penalty. Moving to such a power transmission system does more than provide better matching between fan and turbine shaft speeds. The relative ease with which electrical power can be distributed throughout the aircraft opens up numerous other possibilities for new aircraft and propulsion configurations and modes of operation. This paper discusses a number of these new possibilities. The Boeing N2 hybrid-wing-body (HWB) is used as a baseline aircraft for this study. The two pylon mounted conventional turbofans are replaced by two wing-tip mounted turboshaft engines, each driving a superconducting generator. Both generators feed a common electrical bus which distributes power to an array of superconducting motor-driven fans in a continuous nacelle centered along the trailing edge of the upper surface of the wing-body. A key finding was that traditional inlet performance methodology has to be modified when most of the air entering the inlet is boundary layer air. A very thorough and detailed propulsion/airframe integration (PAI) analysis is required at the very beginning of the design process since embedded engine inlet performance must be based on conditions at the inlet lip rather than freestream conditions. Examination of a range of fan pressure ratios yielded a minimum Thrust-specific-fuel-consumption (TSFC) at the aerodynamic design point of the vehicle (31,000 ft /Mach 0.8) between 1.3 and 1.35 FPR. We deduced that this was due to the higher pressure losses prior to the fan inlet as well as higher losses in the 2-D inlets and nozzles. This FPR is likely to be higher than the FPR that yields a minimum TSFC in a pylon mounted engine. 1

Turboelectric Distributed Propulsion Engine Cycle Analysis for Hybrid-Wing-Body Aircraft

Abstract: Meeting NASA's N+3 goals requires a fundamental shift in approach to aircraft and engine design. Material and design improvements allow higher pressure and higher temperature core engines which improve the thermal efficiency. Propulsive efficiency, the other half of the overall efficiency equation, however, is largely determined by the fan pressure ratio (FPR). Lower FPR increases propulsive efficiency, but also dramatically reduces fan shaft speed through the combination of larger diameter fans and reduced fan tip speed limits. The result is that below an FPR of 1.5 the maximum fan shaft speed makes direct drive turbines problematic. However, it is the low pressure ratio fans that allow the improvement in propulsive efficiency which, along with improvements in thermal efficiency in the core, contributes strongly to meeting the N+3 goals for fuel burn reduction. The lower fan exhaust velocities resulting from lower FPRs are also key to meeting the aircraft noise goals. Adding a gear box to the standard turbofan engine allows acceptable turbine speeds to be maintained. However, development of a 50,000+ hp gearbox required by fans in a large twin engine transport aircraft presents an extreme technical challenge, therefore another approach is needed. This paper presents a propulsion system which transmits power from the turbine to the fan electrically rather than mechanically. Recent and anticipated advances in high temperature superconducting generators, motors, and power lines offer the possibility that such devices can be used to transmit turbine power in aircraft without an excessive weight penalty. Moving to such a power transmission system does more than provide better matching between fan and turbine shaft speeds. The relative ease with which electrical power can be distributed throughout the aircraft opens up numerous other possibilities for new aircraft and propulsion configurations and modes of operation. This paper discusses a number of these new possibilities. The Boeing N2 hybrid-wing-body (HWB) is used as a baseline aircraft for this study. The two pylon mounted conventional turbofans are replaced by two wing-tip mounted turboshaft engines, each driving a superconducting generator. Both generators feed a common electrical bus which distributes power to an array of superconducting motor-driven fans in a continuous nacelle centered along the trailing edge of the upper surface of the wing-body. A key finding was that traditional inlet performance methodology has to be modified when most of the air entering the inlet is boundary layer air. A very thorough and detailed propulsion/airframe integration (PAI) analysis is required at the very beginning of the design process since embedded engine inlet performance must be based on conditions at the inlet lip rather than freestream conditions. Examination of a range of fan pressure ratios yielded a minimum Thrust-specific-fuel-consumption (TSFC) at the aerodynamic design point of the vehicle (31,000 ft /Mach 0.8) between 1.3 and 1.35 FPR. We deduced that this was due to the higher pressure losses prior to the fan inlet as well as higher losses in the 2-D inlets and nozzles. This FPR is likely to be higher than the FPR that yields a minimum TSFC in a pylon mounted engine. 1

Enhanced low-Reynolds-number propulsion in heterogeneous viscous environments

Abstract: It has been known for some time that some microorganisms can swim faster in high-viscosity gel-forming polymer solutions. These gel-like media come to mimic highly viscous heterogeneous environment that these microorganisms encounter in-vivo. The qualitative explanation of this phenomena first offered by Berg and Turner [Nature (London) 278, 349 (1979)], suggests that propulsion enhancement is a result of flagellum pushing on quasi-rigid loose polymer network formed in some polymer solutions. Inspired by these observations, inertia-less propulsion in a heterogeneous viscous medium composed of sparse array of stationary obstacles embedded into a incompressible Newtonian liquid is considered. It is demonstrated that for prescribed propulsion gaits, including propagating surface distortions and rotating helical filament, the propulsion speed is enhanced when compared to swimming in purely viscous solvent. It is also shown that the locomotion in heterogenous viscous media is characterized by improved hydrodynamic efficiency. The results of the rigorous numerical simulation of the rotating helical filament propelled through a random sparse array of stationary obstructions are in close agreement with predictions of the proposed resistive force theory based on effective media approximation.

Optimizing Electric Propulsion Systems for Unmanned Aerial Vehicles

Abstract: The propeller model and a model of the electric system, together with various optimization schemes, are used to design optimal propulsion systems for a mini unmanned aerial vehicle for various goals and under various constraints. Important design trends are presented, discussed, and explained. Although the first part of the investigation is based on typical characteristics of the electric system, the second part includes a sensitivity study of the influence of variations of these characteristics on the optimal system design.

Kestrel -- A Fixed Wing Virtual Aircraft Product of the CREATE Program

Abstract: This paper documents a new integrating product that allows cross-over between simulation of aerodynamics, dynamic stability and control, structures, propulsion, and store separation. The Kestrel software product is an integrating product written in modular form with a Python infrastructure to allow growth to additional capabilities as needed. Computational efficiency will also be improved by targeting the next generation peta-flop architectures envisioned for the 2010+ timeframe. Kestrel is also targeted to the need of simulating multidisciplinary physics, such as fluid-structure interactions, inclusion of propulsion effects, moving control surfaces, and coupled flight control systems. The Kestrel software product is to address these needs for fixed-wing aircraft in flight regimes ranging from subsonic through supersonic flight, including maneuvers, multi-aircraft configurations, and operational conditions. Preliminary results of the F-16C with comparison to experiments are provided. Parallel scalability analysis of the initial version of Kestrel is also presented.

Propulsion Drive Models for Full Electric Marine Propulsion Systems

Abstract: Integrated full electric propulsion systems are being introduced across both civil and military marine sectors. Standard power system analysis packages cover electrical and electromagnetic components but have limited models of mechanical subsystems and their controllers. Hence, electromechanical system interactions between the prime movers, power network, and driven loads are poorly understood. This paper reviews available models of the propulsion drive system components: the power converter, motor, propeller, and ship. Due to the wide range of time constants in the system, reduced-order models of the power converter are required. A new model using state-averaged models of the inverter and a hybrid model of the rectifier is developed to give an effective solution combining accuracy with speed of simulation and an appropriate interface to the electrical network model. Simulation results for a typical ship maneuver are presented.

Orbital Delivery of Small Payloads Using Hypersonic Airbreathing Propulsion

Abstract: Scramjet engines promise significantly higher specific impulse than rockets during the hypersonic phase of low- Earth-orbit insertion trajectories. Despite this, scramjets are not used on any current systems due to the difficulty of operating over the large Mach number envelope required by this accelerating trajectory. The key to taking advantage of airbreathing hypersonic engines for low-Earth-orbit insertion is to develop a multistage system that makes use of the scramjet only within its high-performance regime. Amultistage rocket-scramjet-rocket system that accepts this limitation has therefore been examined. This system includes a solid rocket boost to Mach 6, a near-term Mach 6–12 hydrogen-fueled scramjet engine to propel a reusable second stage, and a liquid-fueled final-stage rocket. Trajectory calculations for a system scaled to deliver approximately 100 kg to a 200 km equatorial orbit indicate payload mass fractions of approximately 1.5% with the use of a scramjet stage designed for low drag and efficient packaging. The goal of this work is to guide the future development of scramjets by identifying the areas that will make the most significant improvement to their use for space access.

Investigation of low discharge voltage Hall thruster characteristics and evaluation of loss mechanisms

Abstract: : During the early development stages of Hall thruster technology, plasma research and propulsion advancements centered primarily on 300 V, 1600 s specific impulse operation. Since the first thruster firing on a Soviet satellite in 1972, extensive investigations of the plasmadynamic discharge phenomena and operating characteristics progressed the propulsion concept to a high-level of performance suitable for a wide range of near-earth maneuvers and interplanetary missions. The expanded performance envelope is primarily a function of improvements in thruster lifetime, thermal margin, discharge stability, and power system capability. Advancements in the Hall thruster propulsion system have enabled a wider range of input parameters to the thruster, including the applied anode potential. Operation in the low discharge voltage regime is associated with a decline in total thruster efficiency. This dissertation is intended to investigate low voltage Hall thruster physics, identify dominant performance loss mechanisms, and determine the discharge characteristics that drive efficiency.

An Overview of Advanced Concepts for Near-Space Systems

Abstract: A brief review of both near-term and far-term platforms proposed for near-space operations is given. The primary focus of the paper is, however, a review of potential advanced propulsion systems for such long-duration near-space platforms. The basic requirements for near-space propulsion systems are defined. Low Reynolds number propellers, the current workhorse, are used as a baseline for comparison. Two broad classifications are identified as potential sources of force in near space: rarefied gas and electric propulsion. Radiometric force propulsion systems, the only candidate propulsion systems found in the open literature, suffer from both significant uncertainty in their underlying physics and from significant operational difficulties. Thermal transpiration propulsion systems were shown fundamentally incapable of providing the required performance. Air-breathing electric propulsion systems for long-duration near-space missions will be significantly different than their in-space counterparts with specific impulses likely under 100s. Electrohydrodynamics propulsion systems show some promise, but have thus far shown limited thrust efficiency at sea level operation, and the efficiency is only predicted to get lower at higher altitudes. The potential effects of systems based on breakthrough physics are also qualitatively discussed. All of the identified potential advanced propulsion concepts for long-duration near-space operations suffer from major technological challenges with significant advancements required for any of them to be viable.

Impact of pulse loads on electric ship power system: With and without flywheel energy storage systems

Abstract: This paper presents the analysis of pulse load operation on the health of a simplified electric ship power system. Two scenarios of the pulse load operation, with and without an energy storage system have been addressed. The energy storage used is a flywheel as it has a very fast time response in supplying high power demands. The health of the electric ship power system is monitored by observing key indicators in the components critical to the working such as the generator and propulsion motor. The time-domain simulation of two test cases is carried out in the PSCAD/EMTDC software platform. The results underscore the vital importance of the flywheel energy storage system in maintaining the stability of the ship power system in the event of pulse load operation.

Low- Speed Aerodynamics and Aeroacoustics of CROR Propulsion Systems

Abstract: Contra Rotating Open Rotor (CROR) propulsion systems have come back into focus as a possible economic and environmentally friendly powerplant for future transport aircraft. Having been widely applied to the simulations of single rotation propellers, the DLR CFD code TAU and the aeroacoustic analysis tool APSIM have been employed for the analysis of the complex aerodynamics and aeroacoustics of this type of aircraft propulsion system. In order to demonstrate the codes applicability to these types of simulations as well as to develop an understanding of the impact of configuration variations, a generic 8x8 and 10x8 pusher CROR powerplant are studied here at typical sea-level take-o conditions of M=0.2. The results allow for a detailed analysis of the aerodynamic interactions between the two rotors as well as the noise generation mechanisms, allowing for an improved understanding of interaction tone sources. In addition, the impact of the numerical approach to the aeroacoustic simulations on the results is studied with a focus on determining the importance of the quadrupole contributions.

Large eddy simulation modelling of combustion for propulsion applications

Abstract: Predictive modelling of turbulent combustion is important for the development of air-breathing engines, internal combustion engines, furnaces and for power generation. Significant advances in modelling non-reactive turbulent flows are now possible with the development of large eddy simulation (LES), in which the large energetic scales of the flow are resolved on the grid while modelling the effects of the small scales. Here, we discuss the use of combustion LES in predictive modelling of propulsion applications such as gas turbine, ramjet and scramjet engines. The LES models used are described in some detail and are validated against laboratory data-of which results from two cases are presented. These validated LES models are then applied to an annular multi-burner gas turbine combustor and a simplified scramjet combustor, for which some additional experimental data are available. For these cases, good agreement with the available reference data is obtained, and the LES predictions are used to elucidate the flow physics in such devices to further enhance our knowledge of these propulsion systems. Particular attention is focused on the influence of the combustion chemistry, turbulence-chemistry interaction, self-ignition, flame holding burner-to-burner interactions and combustion oscillations.

Methodology and Historical Perspective of a Hall Thruster Efficiency Analysis

Abstract: to ionization processes and losses that manifest as Joule heating, and contains no information about the vector properties of the jet. Propellant efficiency incorporates losses from dispersion in the jet composition and is unity for 100% ionization to a single ion species. The effect of neutrals on dispersion of the jet velocity distribution function in propellant efficiency is introduced in the neutral-gain utilization. The beam efficiency accounts for divergence of the jet and is ideal when the ion velocity vectors are parallel to the thrust axis. Plume divergence is defined as a momentum-weighted term, and the approximation as a charge-weighted term is characterized. The efficiency architecture is derived from first principles and is applicable to all propulsion employing electrostatic acceleration, including Hall thrusters and ion thrusters. Distinctions and similarities to several past methodologies are discussed, including past ion thruster analyses, early Russian performance studies, and contemporary architectures. To illustratethepotentialforenhancedunderstandingoflossmechanismsandionizationprocesseswithanarrayoffarfield plume diagnostics, a case study is presented of low-discharge voltage operation from a 6 kW laboratory Hall thruster.

Non-Keplerian orbits for electric sails

Abstract: An electric sail is capable of guaranteeing the fulfilment of a class of trajectories that would be otherwise unfeasible through conventional propulsion systems. In particular, the aim of this paper is to analyze the electric sail capabilities of generating a class of displaced non-Keplerian orbits, useful for the observation of the Sun’s polar regions. These orbits are characterized through their physical parameters (orbital period and solar distance) and the spacecraft propulsion capabilities. A comparison with a solar sail is made to highlight which of the two systems is more convenient for a given mission scenario. The optimal (minimum time) transfer trajectories towards the displaced orbits are found with an indirect approach.

A novel outer-rotor permanent-magnet flux-switching machine for urban electric vehicle propulsion

Abstract: A novel twelve-stator-pole, twenty-two-rotor-pole (12/22) outer-rotor permanent-magnet flux-switching (PMFS) machine for electric propulsion in a lightweight electric vehicle is presented. Analytical equations are derived for the dimensioning of a 3-phase 5kW in-wheel motor. Optimisation techniques are employed to maximise the performance of the machine. The validity of the analytical equations is verified by finite element analysis (FEA). The results show that the PMFS machine combines the key advantages of the PM machines and the switched reluctance machine, and thus demonstrate the viability of the proposed machine as a suitable candidate for in-wheel electric propulsion.

From the Test Benches to the First Prototype of the muFly Micro Helicopter

Abstract: The goal of the European project muFly is to build a fully autonomous micro helicopter, which is comparable to a small bird in size and mass. The rigorous size and mass constraints infer various problems related to energy efficiency, flight stability and overall system design. In this research, aerodynamics and flight dynamics are investigated experimentally to gather information for the design of the helicopter's propulsion group and steering system. Several test benches are designed and built for these investigations. A coaxial rotor test bench is used to measure the thrust and drag torque of different rotor blade designs. The effects of cyclic pitching of the swash plate and the passive stabilizer bar are studied on a test bench measuring rotor forces and moments with a 6---axis force sensor. The gathered knowledge is used to design a first prototype of the muFly helicopter. The prototype is described in terms of rotor configuration, structure, actuator and sensor selection according to the project demands, and a first version of the helicopter is shown. As a safety measure for the flight tests and to analyze the helicopter dynamics, a 6DoF vehicle test bench for tethered helicopter flight is used.

New dawn for electric rockets.

Abstract: The article discusses the usage of electric plasma engines in spacecraft. The engines' application of electric and electromagnetic fields to plasma clouds in order to create thrust is described. The prediction that future electric plasma engines will be able to propel spacecraft to greater speeds for the same amount of propellant as conventional chemical fuel-burning rockets is also noted. INSETS: Chemical vs. Electric Rockets;EARLY HISTORY OF ELECTRIC ROCKETS;The Proven Plasma Propulsion Workhorse;The Latest Plasma Engine Contender

Energy Efficient Hydraulic Hybrid Drives

Abstract: Energy efficiency of propulsion systems for cars, trucks and construction machineries has become one of the most important topics in today’s mobile system design, mainly because of increased fuel c ...

Optimization of Propeller Based Propulsion System

Abstract: Propeller design is a complex task that involves a variety of disciplines such as: aerodynamics, structural analysis, and acoustics. A new method of designing an optimal propeller which is based on a MDO (Multidisciplinary Design Optimization) approach is presented. By combining various analysis tools with an optimization tool, a powerful and flexible design method is obtained. During the design process three different optimization schemes are used, leading the design to its optimal goal. This new method is applied for the design of a propeller for an Ultralight aircraft. Several optional designs for different design goals are presented. The results of the new method are compared with results of the classical design method, based on Betz's condition, which considers only the aerodynamic performance of the propeller. The importance of addressing the characteristics of the entire air-vehicle, its aerodynamic characteristics and its propulsion system (engine, gear box, etc.), rather than only the isolated propeller, is emphasized.

An Investigation of Ionic Wind Propulsion

Abstract: A corona discharge device generates an ionic wind and thrust, when a high voltage corona discharge is struck between sharply pointed electrodes and larger radius ground electrodes. The objective of this study was to examine whether this thrust could be scaled to values of interest for aircraft propulsion. An initial experiment showed that the thrust observed did equal the thrust of the ionic wind. Different types of high voltage electrodes were tried, including wires, knife-edges, and arrays of pins. A pin array was found to be optimum. Parametric experiments, and theory, showed that the thrust per unit power could be raised from early values of 5 N/kW to values approaching 50 N/kW, but only by lowering the thrust produced, and raising the voltage applied. In addition to using DC voltage, pulsed excitation, with and without a DC bias, was examined. The results were inconclusive as to whether this was advantageous. It was concluded that the use of a corona discharge for aircraft propulsion did not seem very practical.

Low-Cost Pathway to Ultra Efficient City Car: Series Hydraulic Hybrid System with Optimized Supervisory Control

Abstract: A series hydraulic hybrid concept (SHHV) has been explored as a potential pathway to an ultra-efficient city vehicle. Intended markets would be congested metropolitan areas, particularly in developing countries. The target fuel economy was ~100 mpg or 2.4 l/100km in city driving. Such an ambitious target requires multiple measures, i.e. low mass, favorable aerodynamics and ultra-efficient powertrain. The series hydraulic hybrid powertrain has been designed and analyzed for the selected light and aerodynamic platform with the expectation that (i) series configuration will maximize opportunities for regeneration and optimization of engine operation, (ii) inherent high power density of hydraulic propulsion and storage components will yield small, lowcost components, and (iii) high efficiency and high power limits for accumulator charging/discharging will enable very effective regeneration. The simulation study focused on the SHHV supervisory control development, to address the challenge of the low storage capacity of the accumulator. Two approaches were pursued, i.e. the thermostatic SOC control, and Stochastic Dynamic Programming for horizon optimization. The stochastic dynamic programming was setup using a set of naturalistic driving schedules, recorded in normal traffic. The analysis included additional degree of freedom, as the engine power demand was split into two variables, namely engine torque and speed. The results represent a significant departure from the conventional wisdom of operating the engine near its “sweet spot” and indicate what is preferred from the system stand-point. Predicted fuel economy over the EPA city schedule is ~93 mpg with engine idling, and ~110 mpg with engine shutdowns.

A Four-Quadrant Thrust Estimation Scheme for Marine Propellers: Theory and Experiments

Abstract: A thrust estimation scheme for marine propellers that can operate in the full four-quadrant range of the propeller shaft speed and the vessel speed has been developed. The scheme is formed by a nonlinear observer to estimate the propeller torque and the propeller shaft speed and by a mapping to compute the thrust from the observer estimates. The mapping includes the estimation of the propeller advance ratio. The advance speed is assumed to be unknown, and only measurements of shaft speed and motor torque have been used. The robustness of the scheme is demonstrated by Lyapunov theory. The proposed method is experimentally tested on an electrically driven fixed pitch propeller in open-water conditions, in waves and with a wake screen that scales the local flow down in order to simulate one of the effects of the interaction between the propeller and the vessel hull.

Real-time simulation of a COGAG naval ship propulsion system:

Abstract: Design and optimization of the propulsion system is a crucial task of the ship design process. The behaviour of the propulsion system, in transient conditions as well as in steady state, is greatly...