Propulsion Technology Research Articles

Reversionary Control Modes for the Mitigation of Failures in a Partially Turboelectric Aircraft Propulsion System

Abstract In support of emission and fuel burn reduction goals, the aviation industry is actively pursuing the advancement of electrified aircraft propulsion (EAP) technology. This includes turboelectric and hybrid electric propulsion designs that combine gas turbine engine and electrical system hardware. Such architectures exhibit a high degree of coupling between subsystems. This drives the need for system-level control strategies to ensure the safe, coordinated, and efficient operation of all subsystems. The design and certification of any aircraft propulsion system requires that all potential subsystem failures are identified, and the hazards posed by these failures are appropriately mitigated. This requirement is particularly challenging for EAP systems due to their integrated nature. One approach to assist in EAP failure mitigation is the inclusion of automated reconfiguration capabilities within the propulsion control system. Such control modes, referred to as reversionary control modes, are designed to automatically detect failures and activate backup control modes upon failure detection. This paper covers the design and evaluation of reversionary control mode logic developed for a partially turboelectric propulsion concept. Test results from a real-time hardware-in-the-loop evaluation of the concept are also presented and discussed. The results show that the developed reversionary control logic can successfully detect and mitigate subsystem failures in a representative environment that includes actual electrical system hardware.

Impact assessment of future fleet compositions in vehicle emissions in urban areas: A methodological framework and a case study

This study explores the impact of emerging vehicle technologies on direct urban traffic emissions. It investigates emission reduction potential from shifts in fleet compositions and modal choices, especially considering climate change. To achieve this, three key research areas are explored for historical, current, and future scenarios (up to 2050): mode choice, emission factors for different vehicle categories, and diverse vehicle propulsion technologies. The estimation of the modal split is pivotal, developing a methodology utilizing Stated Preference survey data, discrete choice modeling, Monte Carlo simulations, and macroscopic traffic simulations. Future scenarios derive from the reference year’s modal split, and emission factors and fleet compositions are predetermined via an extensive literature review, aiding the assessment of their respective emissions. A subsequent sensitivity analysis identifies the impact of specific parameters on emissions, guiding future research focus. Study results underscore differences in greenhouse gas emissions and primary air pollutants between base and future scenarios.

Circulation-controlled wind-assisted ship propulsion: Technical innovations for future shipping industry decarbonization

Amidst mandatory policies aimed at energy savings and emission reductions in the shipping industry, wind-assisted ship propulsion technology has gained prominence for its immediate practicality in promoting environmental sustainability. Wing-sails possess favorable aerodynamic characteristics and adjustable capabilities, yet their efficiency is impeded by flow separation at high angles of attack. This study addressed the challenge of mitigating delayed separation and enhancing lift at large angles of attack for wing-sails through technical solutions involving trailing-edge circulation control and leading-edge boundary layer control. Three-dimensional steady-state flow fields of conventional and circulation-controlled wing-sails were accurately modeled using a Generalized k-ω (GEKO) model across angles of attack ranging from 0° to 30°. Under moderate jet strength conditions with a velocity ratio of 5, the stall angle of attack of the circulation-controlled wing-sail was delayed by approximately 6°. Furthermore, compared to a conventional wing-sail, the circulation-controlled variant exhibited a 111 % increase in maximum lift coefficient and a 120 % rise in maximum resultant force coefficient. The energy-saving and emission reduction benefits of implementing this innovative technology were quantified using the Energy Efficiency Design Index (EEDI) on a real very large crude carrier (VLCC). The circulation-controlled wing-sail demonstrated a 10.38 % reduction in EEDI under optimal operating conditions with medium jet strength, compared to an unassisted vessel. Moreover, this reduction was enhanced by 77.55 % compared to incorporating a conventional wing-sail. These discoveries signify an advancement in wind-assisted ship propulsion technology on an innovative frontier, promising greater energy utilization and reduced fuel consumption, thereby facilitating the achievement of stringent green ship standards.

The Magnet Engine

This research paper explores Michel K. Walden's Magnetite Engine and its transformative potential in engineering. The Magnetite Engine represents a significant advancement in propulsion technology, promising greater efficiency and performance than conventional combustion engines. Through a literature review and case studies, the paper assesses the engine's theoretical and practical aspects, focusing on its impact on automotive and aerospace industries. While it offers benefits like reduced emissions and improved energy efficiency, challenges such as scaling production and infrastructure integration remain. Future research directions are proposed to fully realize the Magnetite Engine's potential for sustainable engineering solutions.

Experimental investigation on the hydrodynamic performance of a bioinspired manta-ray underwater vehicle in various forward propulsion modes

Bionic propulsion technology is revolutionizing underwater exploration by enabling underwater vehicles to navigate the oceans more efficiently. This research developed a scaled-down (10:1) experimental prototype of bionic manta-ray underwater vehicle, which has two degrees of freedom (2-DOF) pectoral fins: flapping and rotating. The impact of four different pectoral fin motion patterns (sinusoidal flapping and rotating, flapping frequency asymmetric, flapping amplitude offset, and rotating amplitude limitation) on the forward propulsion performance was investigated experimentally in a static water tunnel using a force/torque sensor and power analyzer. The results revealed that introducing asymmetry into the fin's flapping motion (asymmetric frequency or amplitude) significantly improved both average thrust and propulsive efficiency (the average thrust can be increased by more than 30%). Flapping with amplitude offset can effectively adjust its pitching moment without sacrificing much thrust. While the rotating motion of the pectoral fins contributes minimally to thrust generation compared to flapping, it plays an important role in enhancing both longitudinal stability and propulsive efficiency. Understanding the hydrodynamic performance of these various forward propulsion modes provides valuable insights for optimizing control strategies of bionic manta-ray underwater vehicles.

Aircraft Electrification: Insights from a Cross-Sectional Thematic and Bibliometric Analysis

Electrifying aircraft, a crucial advancement in the aviation industry, aims to cut pollutive emissions and boost energy efficiency. Traditional aircraft depend on fossil fuels, which contribute significantly to greenhouse gas emissions and environmental pollution. Despite progress in electric propulsion and energy storage technologies, challenges such as low energy density and integration issues persist. This paper provides a comprehensive thematic and bibliometric analysis to map the research landscape in aircraft electrification, identifying key research themes, influential contributors, and emerging trends. This study applies natural language processing to unstructured bibliographic data and cross-sectional statistical methods to analyze publications, citations, and keyword distributions across various categories related to aircraft electrification. The findings reveal significant growth in research output, particularly in energy management and multidisciplinary design analysis. Collaborative networks highlight key international partnerships, with the United States and China being key research hubs, while citation metrics highlight the impact of leading researchers and institutions in these countries. This study provides valuable insights for researchers, policymakers, and industry stakeholders, guiding future research directions and collaborations.

Multi-objective design optimization and physics-based sensitivity analysis of field emission electric propulsion for CubeSat platforms

Field-emission electric propulsion is an electrostatic space electric propulsion technology that offers various advantageous features including efficient design, high specific impulse, and versatile thrust capabilities ranging from micro-Newton to milli-Newton levels. These characteristics make this type of propulsion a promising technology for small satellite platforms, enabling precise attitude control, orbit maintenance, and de-orbiting through ionization and acceleration of a liquid metal propellant. The growing demand for small propulsion systems in CubeSat platforms has spurred significant progress in modeling and characterizing field emission electric propulsion thrusters to enhance their overall performance. However, little study has been conducted to investigate the effect of geometric configurations on electric fields or expelled ion trajectories for design optimization. In this study, multi-objective design optimization is performed by incorporating electrostatic simulation coupled with an analytical performance model into evolutionary algorithms based on prediction from surrogate modeling, aiming to optimize the thruster emission design to maximize thruster performance. Physical insights into the key design factors influencing the performance of field emission electric propulsion have been gained by probing into the interaction between ion particles and electric field behavior within the thruster. It has been found that the length of the emitter tip has a significant effect on plume divergence, i.e., a longer emitter tip under the influence of electric field at higher emitter current tends to result in lower initial acceleration of emitted ions and subsequently wider spread or divergence of the ion beam. A shorter emitter tip, on the other hand, generates a sharper E-field gradient, resulting in a more focused and narrower ion beam. Additionally, sensitivity analysis has identified the mass flow rate and potential distributions as the most influential design factors on performance due to the active roles they play in the performance generation process.

Optimization of Plasma-Propelled Drone Performance Parameters

Recently, the world’s first plasma-propelled drone was successfully flown, demonstrating that plasma propulsion technology is suitable for drone flight. The research on plasma propulsion drones has sparked a surge of interest. This study utilized a proxy model and the NSGA-II multi-objective genetic algorithm to optimize the geometric parameters based on staggered thrusters that affect the performance of electroaerodynamics (EAD) thrusters used for solid-state plasma aircraft. This can help address key issues, such as the thrust density and the thrust-to-power ratio of solid-state plasma aircraft, promoting the widespread application of plasma propulsion drones. An appropriate sample set was established using Latin hypercube sampling, and the thrust and current data were collected using a customized experimental setup. The proxy model employed a genetically optimized Bayesian regularization backpropagation neural network, which was trained to predict the effects of variations in the geometric parameters of the electrode assembly on the performance parameters of the plasma aircraft. Based on this information, the maximum achievable value for a given performance parameter and its corresponding geometric parameters were determined, showing a significant increase compared to the sample data. Finally, the optimal parameter combination was determined by using the NSGA-II multi-objective genetic algorithm and the Analytic Hierarchy Process. These findings can serve as a basis for future researchers in the design of EAD thrusters, helping them produce plasma propulsion drones that better meet specific requirements.

The Challenges of Naval Electromobility in Amazônia

Introduction: This study aims to assess the feasibility of replacing a diesel-powered tourist boat with a Solar Electric Hybrid Catamaran with a capacity for fifty people to promote sustainable tourism in the Amazon, specifically in the Belém-Pará region. The initiative seeks to take advantage of the opportunity presented by COP 2030 to innovate in the waterway transportation matrix through renewable energy sources. The research is based on sustainability concepts, the environmental impacts of using fossil fuels and the advantages of using solar energy for waterway transportation. The methodology includes a comparative analysis of diesel-powered vessels' operational and environmental costs and a Hybrid Electric system based on data compiled from a master's thesis. The expected results include identifying significant benefits in terms of reduced carbon emissions. The discussion will address the challenges faced in implementation, such as the initial investment costs, the maintenance of the new technologies, and the adaptation of operators and tourists to the latest transportation conditions. The implications of this research are vast; it can serve as an incentive for energy transition in the river transportation sector. Furthermore, this research pioneers the proposal of replacing diesel-powered tourist boats with solar electric hybrid models in the Amazon region. The study adds value by presenting a practical and sustainable solution to the environmental challenges the tourism sector faces, in line with the global sustainability goals set by COP 2030. Objective: This research outlines the importance and potential of naval electric mobility in the Eastern Amazon region, highlighting its relevance within COP 2030 and the SDGs for promoting ecotourism for the Amazon region. Theoretical Framework: The research is based on sustainability concepts, the environmental impacts of using fossil fuels, and the advantages of using solar energy for water transportation. In addition, previous experiences of implementing similar technologies in other regions and the potential for replicability in the Amazon are considered, focusing on environmental conservation and economic development. Method: This research is a compilation of the master's thesis entitled "Waterway electric propulsion technologies: conceptual design of a hybrid vessel with a focus on meeting environmental, social and Governance (ESG) practices," where the study was carried out in the municipality of Belém, Pará in the year 2023. Results and Discussion: The expected results include identifying significant benefits in terms of reduced carbon emissions, lower noise pollution and improved air quality. The discussion will address the challenges faced in implementation, such as initial investment costs, maintaining the new technologies and adapting operators and tourists to the new transportation conditions. Social acceptance and the potential for a positive impact on local tourism will also be assessed. Research Implications: This research has vast implications, ranging from contributing to climate change mitigation to promoting more sustainable tourism practices in the Amazon. Adopting the Solar Electric Hybrid Catamaran can serve as a model for other areas with similar geographical characteristics, encouraging public policies aimed at using renewable energies in the transportation sector. Originality/Value: This research pioneers the proposal of the replacement of diesel-powered tourist boats with a solar electric hybrid model in the Amazon region. The study adds value by presenting a practical and sustainable solution to the environmental challenges faced by the tourism sector, which is in line with the global sustainability goals set by COP 2030.

Kinetic Simulation of Nozzle Flow in a Micronewton-Class Cold Gas Thruster

Many scientific space missions need highly precise attitude and orbit control or ultrafine drag compensation, which relies on the variable-thrust propulsion technology operating at the micronewton level. Cold gas thruster (CGT) is a very promising solution, mainly because of its high reliability. One of the keys to the success of micronewton variable-thrust CGT is to understand the flow in its nozzle, whose configuration is much more complex than traditional CGT nozzles. This paper applies kinetic-based multiscale models to investigate the gas flow in the complex nozzle of a micronewton variable-thrust CGT. The simulations reveal that the flow simultaneously experiences all kinds of regimes from continuum to free molecular. The continuum breakdown is likely to occur near the throat region due to large gradients of flow variables and in the expander due to low gas density. Frictional choking is observed, and the nozzle length can be optimized to improve the thruster performance. Nozzle performance measures such as thrust, discharge coefficient, and thrust efficiency are found to change only with the throat Knudsen number Knt. The performance curves can be divided into two sections at Knt≃0.1, and thereby an empirical piecewise formula for thrust prediction is proposed.

DYNAMICS AND STABILITY OF EMERGENCY VEHICLES ON DIFFICULT TERRAIN

This research paper examines the nuances of the dynamics and stability of emergency vehicles when maneuvering over complex terrain, offering a multifaceted analysis that combines theoretical modeling and empirical research. Central to the considerations is the study of the interaction between vehicle design and features of various landscapes, including mountain, forest and urban environments. The research uses a synergistic approach that interweaves advanced mathematical modeling techniques such as computational fluid dynamics and finite element analysis with experimental validation in real-world conditions. The methodology clarifies the critical role of vehicle design parameters, such as suspension tuning and aerodynamic properties, in determining vehicle performance in challenging environments. The study highlights the relevance of terrain-dependent speed limits and maneuvering strategies, advocating for modular vehicle designs and terrain-independent technologies. The paper not only makes a significant contribution to the optimization of emergency vehicles, but also paves the way for future research in the areas of artificial intelligence-driven control systems, sustainable propulsion technologies, and predictive performance modeling. Integrated solutions in this area re key to improving the efficiency and safety of rescue operations in diverse and challenging environments.

Confined Z-Pinch Magnetic Nozzle : A New Approach to Space Propulsion System that Utilizes Trapped Charged Particles

This paper provides a theoretical overview of a Z-pinch magnetic nozzle plasma propulsion system designed for Low Earth Orbit (LEO). The system utilizes trapped charged particles from the spacecraft's environment and magnetic confinement to generate thrust, reducing the need for onboard propellants. By employing a magnetic mirror configuration, the plasma is confined and accelerated to create propulsion. The proposed propulsion system is tailored to function in the dynamic space radiation environment of LEO, particularly in polar orbits, accounting for variations in solar activity that affect trapped protons and electrons. The mechanism involves converting magnetic plasma energy into directed kinetic energy, facilitating efficient plasma detachment and momentum transfer to the spacecraft. This study examines the feasibility, design overview, and constraints of implementing this propulsion technology. Key challenges include the variability of the space environment, technological complexities, radiation effects, plasma detachment efficiency, energy requirements, and material durability. Overcoming these challenges through innovative engineering and rigorous testing is essential for successful implementation. The Z-pinch magnetic nozzle plasma propulsion system promises to advance space propulsion technology, offering a more efficient and cost-effective method for satellite operations in LEO. With further research and development, it has the potential to support future satellite missions and space exploration initiatives.

Design of 2-DOF Thrust vector control system for Rockets and Missiles

This paper outlines the development and implementation of a Thrust Vector Control (TVC) system tailored specifically for solid propellant rocket engines, aimed at enhancing the portability of hybrid and liquid propellant rocket systems. The proposed system ensures trajectory stability and rapid response to flight emergencies by effectively addressing external perturbations like wind. Key components are Gyroscopic (GYRO) sensors, good micro-controller, and Servo motors, collectively referred to as Thrust vectoring components, which dynamically adjust thrust direction opposite to the rocket's trajectory to maintain stability. Drawing from an extensive literature review analyzing existing TVC system designs, with a focus on thrust characteristics and engine combustion timings, the design integrates considerations of geometric properties, kinematics, forces, energy requirements, safety, cost, and control methods, aligning with both mechanical and avionic design principles. The anticipated outcome is an advancement in rocket propulsion technology, characterized by improved angular speed control, trajectory linearity, and rapid response capabilities.

Theoretical Investigation of Laser Ablation Propulsion Using Micro-Scale Fluid in Atmosphere

Laser ablation propulsion based on liquid propellants is a type of propulsion technology with a high specific impulse and good controllability that can be applied to space thrusters, gas metal arc welding, and extreme ultraviolet light. However, its basic mechanisms, such as flow evolution and thrust formation, have not yet been described in detail. In this study, the laser ablation of micro-scale fluid in the atmosphere was investigated. Flow evolution with different laser energy and fluid mass was observed using a schlieren system. According to the characteristic of flow evolution, a theoretical model of laser ablation propulsion in the atmosphere was established. For the first time, a theoretical hypothesis was proposed that the laser energy is divided into two parts, which act on fluid and air respectively. The model indicates that the impulses generated by fluids and air follow power laws with the laser energy, while the exponentials are 0.5 and 1, respectively. In the atmosphere, due to the shielding effect of a laser-maintained detonation wave on laser, the energy absorbed by the fluid is basically unchanged, while only the energy absorbed by the air changes. Significantly, the theoretical model is consistent with the impulse experiment and current studies.

Preliminary Sizing of High-Altitude Airships Featuring Atmospheric Ionic Thrusters: An Initial Feasibility Assessment

When it comes to computing the values of variables defining the preliminary sizing of an airship, a few standardized approaches are available in the existing literature. However, when including a disruptive technology in the design is required, sizing procedures need to be amended, so as to be able to deal with the features of any additional novel item. This is the case of atmospheric ionic thrusters, a promising propulsive technology based on electric power, where thrusters feature no moving parts and are relatively cheap to manufacture. The present contribution proposes modifications to an existing airship design technique, originally conceived accounting for standard electro-mechanical thrusters, so as to cope with the specific features of new atmospheric ionic thrusters. After introducing this design procedure in detail, its potential is tested by showing results from feasibility studies on an example airship intended for a high-altitude mission. Concurrently, the so-obtained results allow the demonstration of the sizing features corresponding to the adoption of atmospheric ionic thrusters at the current level of technology, comparing them to what is obtained for the same mission when employing a standard electro-mechanical propulsion system.

Analysis of Development Trends for Rotating Detonation Engines Based on Experimental Studies

Rotating detonation engines (RDEs), which are Humphrey cycle-based constant-volume combustion engines, utilize detonation waves to attain higher efficiencies compared with conventional constant-pressure combustion engines through pressure gain. Such engines have garnered significant interest as future propulsion technologies, and thus, numerous research and development initiatives have been launched specific to RDEs in various forms. This paper presents a survey of research and development trends in RDE operating systems, based on experimental studies conducted worldwide since the 2010s. Additionally, a performance comparison of RDEs developed to date is presented.

Experimental Thrust and Specific Impulse Analysis of Pulsed Detonation Combustor

Detonation combustion represents a significant advancement in efficiency over traditional deflagration methods. This paper presents a Pulsed Detonation Combustor (PDC) model that is designed with an aerodynamic mixing chamber featuring Hartmann–Sprenger resonators and crossflow injection. This design enhances operational cycle frequency and enables sustained detonation over short distances (below 200 mm). The PDC’s performance was evaluated through a comprehensive full-factorial experimental campaign, incorporating four factors with four discrete levels each. Testing was conducted using both hydrogen/air and hydrogen/oxygen mixtures, highlighting the PDC’s potential as a carbon-free combustion chamber suitable for both air-breathing and space-based propulsion systems. One advantage is the versatility of our PDC breadboard, which lies in its applicability to both terrestrial and in-space applications, such as interplanetary travel or trajectory corrections. Thrust measurements were recorded using a load cell and time-averaged thrust levels were determined over the detonation cycle and are reported herein, together with the specific impulse. The results underscore the PDC’s promise as an efficient propulsion technology for future aerospace applications.

Experimental investigation of camless air engine to improve performance by the novel controller and exhaust pressure predicting technique

In the face of the climate crisis, hike in prices of petroleum products, and limited gasoline sources, it is imperative to explore the possible opportunities in the field of energy transformation technology. Non-conventional and non-hazardous green fuel-air engine technology has proven to have a promising future in propulsion technology. In the air engine, the camless mechanism has created scope for research by replacement option of cam-follower with variable valve train (solenoid valve), which can be controlled electronically. In this paper, work is done on the operational parameters (i.e., cycle time, flow rate, and crank position) of camless air engines and proposed a controlling mechanism with experimental results to improve the system's efficiency. Control of intake duration maximizes the utilization of input compressed air power by allowing the optimum amount of air to expand fully. The novel controller was designed, developed, and tested, which controls the engine intake duration by estimating exhaust pressure. A prototype model was built with an electronic control circuit and pneumatic system, which records signals of operational parameters with the help of feedback sensors and controls the engine's intake duration at different operating pressure ranging from 3 to 6.5 bar. Experiments were conducted, and the results of two cycles were compared, case-I, where compressed air is continuously supplied from 0° to 170° of crank angle, and case-II controlled cycle, which controls intake duration by estimating exhaust pressure. Results show the average efficiency improvement of 11.91 % in case-II compared to case-I and also improvement in work done and RPM (Revolution per Minute) of the cycle. Thus, the control system in a camless air engine increases the feasibility of the air engine as one of the propulsion technologies in a city vehicle and even in the Compressed Air Energy Storage System (CAES).

Solutions for decarbonising urban bus transport: a life cycle case study in Saudi Arabia

With heavy reliance on fossil fuels, countries like Saudi Arabia face challenges in reducing carbon emissions from urban bus transportation. Herein, we address the gaps in evaluating proton-exchange membrane fuel cell buses and develop a globally relevant life-cycle assessment model using Saudi Arabia as a case study. We consider various bus propulsion technologies, including fuel cell buses powered by grey and blue hydrogen, battery electric buses, and diesel engines, and include the shipping phase, air conditioning load, and refuelling infrastructure. The assessment illustrates fuel cell buses using blue hydrogen can reduce emissions by 53.6% compared to diesel buses, despite a 19.5% increase in energy use from carbon capture and storage systems. Battery electric buses are affected by the energy mix and battery manufacturing, so only cut emissions by 16.9%. Sensitivity analysis shows climate benefits depend on energy sources and efficiencies of carbon capture and hydrogen production. By 2030, grey and blue hydrogen-powered fuel cell buses and battery electric buses are projected to reduce carbon emissions by 19.3%, 33.4%, and 51% respectively, compared to their 2022 levels. Fully renewable-powered battery electric buses potentially achieve up to 89.6% reduction. However, fuel cell buses consistently exhibit lower environmental burdens compared to battery electric buses.

Sustainable propulsion technology selection in penultimate mile delivery using the FullEX-AROMAN method

Sustainable transport is the priority for future cities and society. It is necessary to make sustainable urban transport policies to mitigate the harmful effects of current transportation systems. One of the essential issues in making cities cleaner is the propulsion technology of light commercial vehicles (LCVs). Most of the LCVs are compressed natural gas (CNG) and diesel-powered. However, cleaner, sustainable power sources, such as hydrogen, hybrid, solar, and electric have appeared in the market. This paper addresses the selection of propulsion technology for LCVs up to 3.5 tones for the Czech Post vehicle fleet. In this study, three main pillars are considered: economic, socio-environmental, and technical. Czech Post currently uses CNG-powered vehicles to transport shipments in penultimate mile delivery. The integrated FullEX-alternative ranking order method accounting for the two-step normalization (AROMAN) approach selects the best sustainable propulsion technology for the Czech Post vehicle fleet. The FullEX method identifies the criteria weights, while the AROMAN method ranks propulsion technologies. The results of the integrated approach reveal that the best propulsion technology for penultimate mile delivery is electrically powered, followed by hydrogen, hybrid, and CNG. A comparative analysis with other multi-criteria decision-making methods is also performed. The results confirm that the electrically powered solution is the best. The sensitivity analysis is carried out. The FullEX-AROMAN shows high resilience.