Conventional Propulsion Systems Research Articles

Installed Performance Assessment of an Array of Distributed Propulsors Ingesting Boundary Layer Flow

Conventional propulsion systems are typically represented as uninstalled systems to suit the simple separation between airframe and engine in a podded configuration. However, boundary layer ingesting systems are inherently integrated, and require a different perspective for performance analysis. Simulations of boundary layer ingesting propulsions systems must represent the change in inlet flow characteristics, which result from different local flow conditions. In addition, a suitable accounting system is required to split the airframe forces from the propulsion system forces. The research assesses the performance of a conceptual vehicle, which applies a boundary layer ingesting propulsion system—NASA's N3-X blended wing body aircraft—as a case study. The performance of the aircraft's distributed propulsor array is assessed using a performance method, which accounts for installation terms resulting from the boundary layer ingesting nature of the system. A “thrust split” option is considered, which splits the source of thrust between the aircraft's main turbojet engines and the distributed propulsor array. An optimum thrust split (TS) for a specific fuel consumption at design point (DP) is found to occur for a TS value of 94.1%. In comparison, the optimum TS with respect to fuel consumption for the design 7500 nmi mission is found to be 93.6%, leading to a 1.5% fuel saving for the configuration considered.

Numerical simulation and performances evaluation of the pulse detonation engine

A pulse detonation engine (PDE) is a type of propulsion system that uses detonation waves to combust the fuel and oxidizer mixture. The engine is pulsed because the mixture must be renewed in the combustor between each detonation wave. Theoretically, a PDE can operate from subsonic up to hypersonic flight speed. Pulsed detonation engines offer many advantages over conventional propulsion systems and are regarded as potential replacements for air breathing and rocket propulsion systems, for platforms ranging from subsonic unmanned vehicles, long range transports, high-speed vehicles, space launchers to space vehicles. The article highlights elements of the current state of the art, but also theoretical and numerical aspects of these types of unconventional engines. This paper presents a numerical simulation of a PDE at h=10000 m with methane as working fluid for stoichiometric combustion, in order to find out the detonation conditions.

Development of a software tool for comprehensive flight performance and mission analysis of hybrid-electric aircraft

This paper presents a software tool developed to comprehensively evaluate flight performance and mission analysis of hybrid-electric aircraft. The modelling incorporates conventional propulsion systems as well as an alternative electric propulsion system for flight performance and mission analysis. As part of the overall technology assessment of the Bavarian research project “PowerLab”, which aims to develop a hybrid-electric flying platform, this tool is incorporated to assess the reference missions of the project concept. Further analysis on the impact of energy density variation on the transport efficiency using the developed tool was also performed. Finally we present an outlook into the integration of the tool in an overall aircraft fleet system dynamics model to estimate future fleet development for various future scenarios.

Analysis of Engine Propeller Matching of DC Motor as a Main Propulsion

The development of ship always searches through the most benefits system for reducing costs of propulsion system without increase pollution. Diesel propulsion system or also known as conventional propulsion system is efficient but requires high operating costs and increase high level of marine pollution. Electrical propulsion system is using electric motors as the prime mover of the propeller. There are 2 types of electric motors that will be used for research of electric propulsion system, there are; DC motors and three-phases induction motor. As the use of DC motor as a prime mover for this electrical propulsion system, this study determines the characteristic between voltage terminal with torque and also field current with torque. It results that torque produced by the DC motor is in the same magnitude with the speed (RPM). The higher the speed have shaped the value of the torque. The input and terminal voltages adjusts all variables and results. In this study, different field voltage creates different pattern of motor envelope. Its manner to propeller curve occurs total different results. With field voltage of 50 V, the ranges of motor envelope immoveable in the point of 150% of present speed and 160%. While field voltage of 60 V serves larger ranges of motor envelope which possible to reach further than 50 V curve.

Energy Efficient and Environmentally Friendly Hybrid Conversion of Inland Passenger Vessel

Abstract The development and growing availability of modern technologies, along with more and more severe environment protection standards which frequently take a form of legal regulations, are the reason why attempts are made to find a quiet and economical propulsion system not only for newly built watercraft units, but also for modernised ones. Correct selection of the propulsion and supply system for a given vessel affects significantly not only the energy efficiency of the propulsions system but also the environment - as this selection is crucial for the noise and exhaust emission levels. The paper presents results of experimental examination of ship power demand performed on a historic passenger ship of 25 m in length. Two variants, referred to as serial and parallel hybrid propulsion systems, were examined with respect to the maximum length of the single-day route covered by the ship. The recorded power demands and environmental impact were compared with those characteristic for the already installed conventional propulsion system. Taking into account a high safety level expected to be ensured on a passenger ship, the serial hybrid system was based on two electric motors working in parallel and supplied from two separate sets of batteries. This solution ensures higher reliability, along with relatively high energy efficiency. The results of the performed examination have revealed that the serial propulsion system is the least harmful to the environment, but its investment cost is the highest. In this context, the optimum solution for the ship owner seems to be a parallel hybrid system of diesel-electric type

Regenerative Intelligent Brake Control for Electric Motorcycles

Vehicle models whose propulsion system is based on electric motors are increasing in number within the automobile industry. They will soon become a reliable alternative to vehicles with conventional propulsion systems. The main advantages of this type of vehicles are the non-emission of polluting gases and noise and the effectiveness of electric motors compared to combustion engines. Some of the disadvantages that electric vehicle manufacturers still have to solve are their low autonomy due to inefficient energy storage systems, vehicle cost, which is still too high, and reducing the recharging time. Current regenerative systems in motorcycles are designed with a low fixed maximum regeneration rate in order not to cause the rear wheel to slip when braking with the regenerative brake no matter what the road condition is. These types of systems do not make use of all the available regeneration power, since more importance is placed on safety when braking. An optimized regenerative braking strategy for two-wheeled vehicles is described is this work. This system is designed to recover the maximum energy in braking processes while maintaining the vehicle’s stability. In order to develop the previously described regenerative control, tyre forces, vehicle speed and road adhesion are obtained by means of an estimation algorithm. A based-on-fuzzy-logic algorithm is programmed to carry out an optimized control with this information. This system recuperates maximum braking power without compromising the rear wheel slip and safety. Simulations show that the system optimizes energy regeneration on every surface compared to a constant regeneration strategy.

Computational Fluid Dynamics-Based Analysis of Boundary Layer Ingesting Propulsion

A computational fluid dynamics-based analysis has been performed to assess propulsive efficiency benefits of a boundary layer ingesting propulsion system. This analysis is based on a full-scale configuration at relevant flight conditions defined in previous vehicle-level system studies and component designs and includes the full propulsor geometry. A method to calculate the net thrust, equivalent power, and propulsive efficiency of boundary layer ingesting propulsion systems is presented and applied to the computational fluid dynamics solutions. It was found that the boundary layer ingesting system results in a propulsive efficiency benefit of 4.2–4.5% over that of a conventional propulsion system for the case of a fan designed primarily for aerodynamic performance. These results compare favorably to those predicted by engine cycle-based system studies and boundary layer ingesting theory and do not account for anticipated additional nacelle drag reduction benefits. It is recognized that future design work will be required to impart aeromechanics capability to the fan, and thus that the subject results provide an estimate of the upper benefit bound for a full-scale boundary layer ingesting propulsor in a relevant environment.

Hybrid rocket propulsion systems for outer planet exploration missions

Outer planet exploration missions require significant propulsive capability, particularly to achieve orbit insertion. Missions to explore the moons of outer planets place even more demanding requirements on propulsion systems, since they involve multiple large ΔV maneuvers. Hybrid rockets present a favorable alternative to conventional propulsion systems for many of these missions. They typically enjoy higher specific impulse than solids, can be throttled, stopped/restarted, and have more flexibility in their packaging configuration. Hybrids are more compact and easier to throttle than liquids and have similar performance levels. In order to investigate the suitability of these propulsion systems for exploration missions, this paper presents novel hybrid motor designs for two interplanetary missions. Hybrid propulsion systems for missions to Europa and Uranus are presented and compared to conventional in-space propulsion systems. The hybrid motor design for each of these missions is optimized across a range of parameters, including propellant selection, O/F ratio, nozzle area ratio, and chamber pressure. Details of the design process are described in order to provide guidance for researchers wishing to evaluate hybrid rocket motor designs for other missions and applications.

A Journey to the Stars: Space Propulsion Brought About by Astrophysical Phenomena Such as Accretion Disk and Astrophysical Jet

At the present stage of space propulsion technology, the only practical propulsion system is chemical propulsion system and electric propulsion system, which are based on expulsion of a mass to induce a momentum thrust. Since the maximum speed is limited by the product of the gas effective exhaust velocity and the natural logarithm of mass ratio, its speed is too slow for the spaceship to achieve the interplanetary travel and interstellar travel. Thus the breakthrough of propulsion method has been required until now. Field propulsion systems, which are based on the General Relativity Theory, the Quantum Field Theory and other exotic theories, have been proposed to overcome the speed limit of the conventional space rocket, instead of conventional chemical propulsion systems.

Hydrodynamic Characterization of USV Vessels with Innovative SWATH Configuration for Coastal Monitoring and Low Environmental Impact

The high costs associated with the use of research oceanographic vessels and the maturity of the unmanned surface vehicles (USV) makes now possible to develop systems for monitoring coastal areas based on networks of independent USVs. This type of vessels is a valid alternative to conventional vessels, which have a limited mission profile due to their high environmental impact (conventional propulsion systems based on polluting fossil fuels) inhibiting their access to protected coastal regions. Moreover, conventional vessels have high hydrodynamic resistance (limiting the autonomy) producing high levels of noise that can dramatically influence the monitoring equipment shipped: beside the environmental impact reduction, there is also the necessity of low-resistance/low-noise hydrodynamic specification. Consequently, the coastal monitoring (of also protected regions) needs unconventional vessels able to address both the issues related to the environmental impact and the hydrodynamic performance.In this framework, this work aims to characterize the hydrodynamic performance of a system based on USV units able to launch and recover autonomous vehicles of different nature (gliders, AUVs, motor-gliders, wire-guided ROVs), and able to acquire environmental data (in the column water from free-surface to the sea floor), in order to meet the requirements of civil and military applications. The cutting-edge aspects that characterize the USV studied are the hull SWATH type (Small Waterplane Area Twin Hulls) non-conventional, optimized so as to ensure a unique seakeeping and a reduced resistance, along with the propulsion system with propellers in mantle, developed to combine propulsive efficiency and low noise. In the present paper, a SWATH-shaped USV designed for monitoring of protected coastal regions is numerically studied solving the Navier-Stokes equations on the fully appended vessels with several environmental conditions. An accurate hydrodynamic characterization will presented in order to investigate its performances and eventual maneuverability issues.

Performance of Contra-Rotating Propellers for Stratospheric Airships

Small advance ratio and low Reynolds number of stratospheric propulsion system bring lots of challenges to the design of propellers. Contra-rotating propeller configuration is proposed to improve the propulsion efficiency. In this paper, the feasibility of contra-rotating propeller for stratospheric airship has been assessed and its performance has been investigated by wind tunnel tests. The experimental results indicate, at relatively low Reynolds number, although the advance ratio is fixed, the performance of propellers is different with variation of Reynolds number. Moreover, at the same Reynolds number, the efficiency of contra-rotating propeller achieved appears to be a few percent greater than that for a standard conventional propulsion system. It can be concluded that contra-rotating propellers would be an efficient means to improve the performance of stratospheric airship propulsion system.

Advanced space power and propulsion based on lasers

One of the key components for future space exploration, manned or unmanned, is the availability of propulsion systems beyond the state of the art. The rapid development in conventional propulsion systems since the middle of the 20th century has already reached the limits of chemical propulsion technology. To enhance mission radius, shorten the transit time and also extend the lifetime of a spacecraft more efficient, but still powerful propulsion system must be developed. Apart from the propulsion system a major weight contribution arises from the required energy source. Envisioning rapid development of future high average power laser systems and especially the ICAN project we review the prospect of advanced space propulsion based on laser systems.

Comprehensive approach to comparative efficiency evaluation of HPS for helicopters

Purpose – The purpose of the work is to carry out analysis of the possibilities and estimation of electric drive efficiency for rotors of helicopter propulsion systems (PS). Design/methodology/approach – Methodology and comprehensive multidisciplinary technology for efficiency estimation of conventional and unconventional architectures PS on rotorcraft system level at preliminary design phase were developed. Findings – Application of the approach allow to carry out analysis of hybrid (based on gas turbine and piston engines) and full electrical PS for superlight-, light- and medium-size helicopters. Practical implications – It was shown what level of electrical technologies improvement may provide positive effect of the using of hybrid and full electrical helicopter PS of different architectures. Originality/value – Close matching of helicopter and engine design and calculation aspects, as well as possibilities to use the external (experimental) performances of engine components, whole PS and helicopter a...

Solar sailing trajectory optimization with planetary gravity assist

Significant propellant mass saving can be obtained with the use of complex multiple intermediate flyby maneuvers for conventional propulsion systems, and trip time also decreases for a portion of the proper solar sail missions. This paper discusses the performance of gravity assist (GA) in the time-optimal control problem of solar sailing with respect to sail lightness number and the energy difference between the initial and final orbit in the rendezvous problem in a two-body model, in which the GA is modeled as a substantial change in the velocity of the sailcraft at the GA time. In addition, this paper presents a method to solve the time-optimal problem of solar sailing with GA in a full ephemeris model, which introduces the third body’s gravity in a dynamic equation. This study builds a set of inner constraints that can describe the GA process accurately. Finally, this study presents an example for evaluating the accuracy and rationality of the two-body model’s simplification of GA by comparison with the full ephemeris model.

Power and protection considerations for TeDP microgrid systems

Purpose – The purpose of this paper is to highlight and discuss the unique safety and protection requirements for the electrical microgrid system in a turboelectric distributed propulsion aircraft. Design/methodology/approach – The NASA N3-X concept aircraft requirements were considered. The TeDP system was decomposed into three subsystems: turbogenerator, distribution system and propulsors. Unique considerations for each of these subsystems were identified. Findings – The fail-safe requirements for a TeDP system require a divergence from the standard safety case used for conventional propulsion systems. Advantages in flight control and single-engine-out scenarios can be realized using TeDP. Additionally, a targeted use of energy storage and reconfigurability may enable seamless response to propulsion systems failures. Practical implications – The concepts discussed in this paper will assist to guide the early conceptual and preliminary design and evaluation of TeDP architectures. Originality/value – The ...

Architectural study of diesel hybrid propulsion systems to meet future fuel economy and emission regulations

Among conventional propulsion systems, the diesel propulsion system is very efficient in terms of fuel economy. However, conventional diesel propulsion systems have to meet aggressive fuel economy and stringent emission regulations. Electrification of the diesel propulsion system can play a major role in achieving future fuel economy and emission standards. In this paper, diesel hybrid propulsion system architectures are presented that could potentially meet future fuel economy and emissions compliance standards for a given set of performance criteria. Three diesel hybrid electric vehicle (D-HEV) architectures; parallel hybrid (PH), power split (PS) and series hybrid (SH) are investigated and analyses of these architectures are conducted. These architectures are compared and evaluated considering trade-offs between fuel economy and emissions targets.

Fundamental Architecture and Analysis of an Antimatter Ultra-Intense Laser Derived Pulsed Space Propulsion System

Antimatter has been generated in large quantities by the Lawrence Livermore National Laboratory Titan laser. The Titan laser is an ultra-intense laser system on the order of approximately 1020W/cm2 with pulse durations of roughly 1ps. With the Titan laser incident on a high atomic number target, such as gold, antimatter on the scale of 2 × 1010 positrons are generated. Roughly 90% of the generated positrons are ejected anisotropic and aft to the respective target. The mechanisms for the laser-derived positron antimatter generation involve electron interaction with the nuclei based on bremsstrahlung photons that yield electron-positron pairs as a consequence of the Bethe-Heitler process, which predominates the Trident process. Given the constraints of the current and near future technology space, a pulsed space propulsion configuration is advocated for antimatter derived space propulsion, similar in concept to pulsed radioisotope propulsion. Antimatter is generated through an ultra-intense laser on the scale of a Titan laser incident on a gold target and annihilated in a closed chamber, representative of a combustion chamber. Upon reaching a temperature threshold, the closed chamber opens, producing a pulse of thrust. The implication of the pulsed space propulsion antimatter architecture is that the energy source for the antimatter propulsion system can be decoupled from the actual spacecraft. In contrast to conventional chemical propulsion systems, which require storage of its respective propulsive chemical potential energy, the proposed antimatter propulsion architecture may have the energy source at a disparate location from the spacecraft. The ultra-intense laser could convey its laser energy over a distance to the actual spacecraft equipped with the positron antimatter pulsed space propulsion system. Hydrogen is considered as the propulsive fluid, in light of its low molecular weight. Fundamental analysis is applied to preliminarily define the performance of the positron antimatter derived pulsed space propulsion system. The fundamental performance analysis of the antimatter pulsed space propulsion system successfully reveals the architecture is viable for further evaluation.

A Collision‐resilient Flying Robot

Flying robots that can locomote efficiently in GPS‐denied cluttered environments have many applications, such as in search and rescue scenarios. However, dealing with the high amount of obstacles inherent to such environments is a major challenge for flying vehicles. Conventional flying platforms cannot afford to collide with obstacles, as the disturbance from the impact may provoke a crash to the ground, especially when friction forces generate torques affecting the attitude of the platform. We propose a concept of resilient flying robots capable of colliding into obstacles without compromising their flight stability. Such platforms present great advantages over existing robots as they are capable of robust flight in cluttered environments without the need for complex sense and avoid strategies or three‐dimensional mapping of the environment. We propose a design comprising an inner frame equipped with conventional propulsion and stabilization systems enclosed in a protective cage that can rotate passively thanks to a three‐axis gimbal system, which reduces the impact of friction forces on the attitude of the inner frame. After addressing important design considerations thanks to a collision model and validation experiments, we present a proof‐of‐concept platform, named GimBall, capable of flying in various cluttered environments. Field experiments demonstrate the robot's ability to fly fully autonomously through a forest while experiencing multiple collisions.

A Study on the Structure of Linear Synchronous Motor for 600km/h Very High Speed Train

Recently, an interest in a hybrid system combining only the merits of the conventional wheel-rail system and Maglev propulsion system is growing as an alternative to high-speed maglev train. This hybrid-type system is based on wheel-rail method, but it enables to overcome the speed limitation by adhesion because it is operated by a non-contact method using a linear motor as a propulsion system and reduce the overall construction costs by its compatibility with the conventional railway systems. Therefore, a comparative analysis on electromagnetic characteristics according to the structural combinations on the stator-mover of Linear Synchronous Motor (LSM) for Very High Speed Train (VHST) maintaining the conventional wheel-rail method is conducted, and the structure of coreless superconducting LSM suitable for 600 km/h VHST is finally proposed in this paper.

Influence of propulsion system configuration on the manoeuvring performances of a surface twin-screw ship

Propulsion system can experience large power absorption fluctuations during tight maneuvers. In the case of a turning circle manoeuvre for a twin-screw ship, the power required by the two shaft lines can be completely different; in case of non conventional propulsion system, like cross-connect configurations, a compromise must be met in order to design a safe control system without affecting dramatically the vessel's manoeuvring performance. In this work, a series of free running model tests on a unmanned surface twin screw ship model have been carried out in order to investigate the influence of different propulsion system operation settings on the vessel's manoeuvring characteristics.