Propulsion Design Research Articles

Modeling and Dynamic Analysis of Fish Robot with Soft Fluidic Actuation

A biomimetic robotic fish tailored for environmental monitoring and hydrographic exploration is examined in this study. Traditional fish robots, driven by tail oscillations, often grapple with constrained maneuverability in a single plane. This article focuses on mitigating these limitations through an exploration of the dynamic behavior of a bioinspired soft robotic fish. Unlike prior designs that employed similar actuators for the robot's tail, which either lacked the ability for out-of-plane motion or relied on other propulsion systems, the single propulsion design proposed in our model enables movement along three-dimensional trajectories, leading to improved efficiency and maneuverability due to tail oscillation dynamics. The proposed design integrates strategically positioned nozzles for out-of-plane movements, alongside parallel fluid channels on the tail's neutral plate. Actuation is achieved by manipulating the internal fluid pressure within these channels. To precisely model tail deflection, we introduce a novel method utilizing Euler–Bernoulli beam theory considering nonlinear characteristics arising from internal fluid stress. For instance, following the proposed approximate analytical method, we optimize the fluidic actuator, considering that the soft tail deformation increases by 65% as the channel shape transitions from a semicircular to a square cross-section. The comprehensive comparison with analytical nonlinear method, finite element method, and experimental-driven analytical method extends our approach as an effective tool in terms of accuracy and computation time, demonstrating the effectiveness of validation processes. This study unveils a simplified and robust fish robot design, outperforming traditional mechanisms in efficacy. Despite its simplicity, the proposed design delivers comparable performance, presenting an effective alternative for achieving requisite functionality in fish robots.

Digital twins for electric propulsion technologies

As the space industry is undergoing an evolution, the current approaches toward design, development, and qualification of Electric Propulsion (EP) systems largely based on empirical “trial-and-error” methodologies are falling short of addressing the emerging needs and keeping abreast of the rapid changes in market trends. Furthermore, with the proliferation of Artificial Intelligence (AI) within the space industry toward next-generation autonomous satellites and spacecrafts, the conventional EP monitoring and control strategies become inadequate and need to give way to approaches compatible with satellite-level autonomy requirements. A digital twin (DT) – a technology capable of providing an accurate dynamically adapting virtual representation of a physical asset – is a game-changing concept that catalyzes the transcendence of the EP industry past its pressing challenges today. In this paper, we aim to: (i) define the DT concept, highlighting how it surpasses traditional modelling, (ii) enumerate the DT’s breakthrough promises for the EP industry, and (iii) specify the challenges to realize practical and scalable EP DTs. Additionally, we report on the technical progress achieved and/or planned at Imperial Plasma Propulsion Laboratory to fill the foundational gaps in three building block elements of DTs, namely, (i) a cost-effective kinetic model to generate extensive high-fidelity databases for machine learning (ML), (ii) ML-enabled models for prediction and analysis of performance and operational behavior, and (iii) a DT architecture that integrates the numerical models in terms of a computing infrastructure and provides data pipelines and interfaces for the DT’s data exchanges with the real world, its dynamic updating, and uncertainty quantification.

Cathode-less RF plasma thruster design and optimisation for an atmosphere-breathing electric propulsion (ABEP) system

Atmosphere-breathing electric propulsion (ABEP) is a concept that ingests residual atmospheric gases as a source of propellant for an electric thruster, removing the need for onboard propellant storage. This would enable continuous low-thrust drag compensation, extending the lifetime of spacecraft in Very-Low Earth Orbit (VLEO); <250 km. VLEO is an appealing region for spacecraft operations, enabling new remote sensing missions with improved radiometric performance and spatial resolution, whilst reducing size, mass and power requirements, as well as mission cost. A preliminary design review and optimisation is therefore conducted for an ABEP system that uses the cathode-less radio frequency (RF) plasma thruster from Technology for Innovation & Propulsion (T4i) S.p.A. This removes the issue of thruster erosion by means of magnetic confinement and offers reduced susceptibility to varying atmospheric composition. A semi-empirical oxygen-nitrogen global source model (GSM) has been developed which considers the volume-averaged flux, momentum, and energy balance of the RF discharge. This includes a detailed chemistry model for the complex electron-molecular reactions and energy-loss channels of air plasma in the ionisation chamber. The GSM is coupled to an analytical model of flux balance for an air intake, verified by Direct Simulation Monte-Carlo (DSMC) simulation, to consider its design for maximum collection efficiency. This is then utilised in a robust multi-objective optimisation of the ABEP system, accounting also for spacecraft aerodynamics and power requirements.

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.

Matching of propulsion system components for a planing hull model

ABSTRACT This study specifies propellers for a main engine and transmission system to reach 20 knots for a vessel of certain dimensions. Propeller designs for 16-20 knots were examined using Fn and speed-resistance prediction. Twenty-four propeller variants are created with a 110 kW main engine and varied reduction rates. Twelve propellers that meet design specifications are CFD analysed. The data show that the P6 propeller consistently generates the most thrust and the P3 the least. Margins of error analysis show that propellers P4, P7 and P9 are closest to performance charts' values. As the advance ratio exceeds thresholds, open water diagram-CFD solver error rates rise. As long as advance ratios are followed, the P4 propeller produces reliable results, limiting error rates. Future studies should include propellers at different speeds further propellers, engines and transmissions. For researchers, professionals and mariners interested in ship propulsion design and effectiveness, this article is crucial.

SIMULATION OF OSCILLATIONS OF THE CENTER OF MASS OF THE TRACTOR WITH TRACKED PROPULSION UNIT

To increase the traction force of tractors while simultaneously reducing the specific pressure on the soil, one of the effective ways is the use of a tracked propulsion unit. The article considers a variant of a tracked propulsion unit, installed separately on each drive axle of the tractor instead of wheels. The basis of the developed design of the tracked propulsion unit is the trackbed, which reduces the pressure on the ground and increases adhesion to the soil.&#x0D; The results of simulation modeling of the rectilinear movement of a tractor with a tracked propulsion unit along grain stubble are presented. Realizations of oscillations of the front, sprung and rear, unsprung axles and the tractor frame were obtained. Oscillations in the ordinates of the reference surface were modeled as a random process with specified values corresponding to the reference surface of the grain stubble.&#x0D; The simulation results showed acceptable oscillation values of the tractor frame with the proposed propulsion design. The proposed propulsion unit can be easily installed on a tractor instead of wheels and, if necessary, can also be easily dismantled.&#x0D; Purpose. Investigation of oscillations of the center of mass of a tractor with a tracked propulsion unit using simulation modeling in the MATLAB Simulink environment.&#x0D; Methodology. Methods of mathematical modeling and analysis were used in the article.&#x0D; Results. The parameters showing the effectiveness of using a tracked propulsion unit instead of wheels on a tractor of traction class 6 are obtained.&#x0D; Practical implications. The results obtained can be applied in the design of tractors to determine the acceptable parameters of the tracked propulsion unit.

Development of propulsion solutions for river-sea ships of the northern Black Sea

Conception of hull form and propulsion design of river-sea ships essentially depends on the restrictions of specific inland waterways. River-sea ships of the Northern Black Sea were historically designed for operation through the locks of European inland waterways of the former Soviet Union. River-sea vessels of the late Soviet Union were designed as simple and technological. After dramatic economical changes the ships of new generation acquired completely different features of general and propulsion design. The vessels had unusually full hull forms and azimuthal thrusters. As is shown in the paper, the full hull forms have sound economic grounds for the considered ship type. However, azimuthal thrusters have controversial features and are not non-alternative. Based on analysis of previous and current propulsion solutions their further development is proposed within the considered ship type. Hull forms designed with specially developed CFD methods are recommended as a further step toward propulsion optimality.

An Enhanced Electromagnetic Rail Propulsion Design Based on Current Self-Guiding

An Enhanced Electromagnetic Rail Propulsion Design Based on Current Self-Guiding

CFD-based hull-engine-propeller matching study after retrofitting propeller boss-cap-fin (PBCF)

Propeller boss-cap-fin (PBCF) is an energy-saving device that can improve propeller propulsion efficiency. The addition of PBCF influences both the propeller characteristic and the engine behaviour. However, there is limited research on the integrated design of PBCF and ship propulsion system.In this paper, Computational Fluid Dynamics (CFD) methods are used to simulate the PBCF performance and the interactions between PBCF and the propeller. The Wageningen B series propellers are used to investigate the PBCF geometry parameters effects on the propeller hydrodynamics. An influence fraction of PBCF is defined and used to modify the propeller open-water characteristic, which is used in the hull-engine-propeller matching process. Then, PBCF is added into the matching process as a module to realize the hull-engine-propeller and PBCF matching. Multiple groups of matching tests with PBCF are set up to investigate its influences on the matching characteristics.In summary, a new ship-propeller-engine matching method for propellers with PBCF has been investigated in this paper, and systematic insights of the influence of PBCF on the propulsion system are provided. The interactions between PBCF and matching characteristic parameters are important to ship propulsion system design and comprehensive evaluation of PBCF performance.

An interactive framework to facilitate probabilistic set-based multidisciplinary design optimisation studies

The upcoming stringent environmental aircraft regulations and the environmental, social and governance (ESG) framework targeting net zero emissions has forced aircraft manufacturers to seek innovative feasible technical solutions. Often, there is the need to consider entirely radical solutions, such as hybrid-electric aircraft, which are not fully understood when compared with conventional kerosene driven aircraft. The recent development of a probabilistic set-based multidisciplinary optimisation methodology has demonstrated the ability to explore trade-offs when the requirements are uncertain. In this way, the weaknesses and potential to enable the feasibility of hybrid-electric aircraft can be studied from a systems perspective but maintaining the connection with more detailed trade-off studies of components of the sub-systems. We have developed an interactive interface, where the user is guided through the steps of the design methodology and the produced data is visualised to aid an informative decision-making process. In our illustrative case study, decision-makers are enabled to interactively explore the hybrid-electric propulsion design space while considering the impact to the figures of merit from expected improvements in the coming years of key enabling technologies, such as energy storage.

A novel and efficient dual-antenna micro plasma thruster

A novel dual-antenna micro plasma thruster (DMPT) driven by radio-frequency (rf) power supply is proposed and characterized experimentally. The Langmuir probe (LP) and the retarding potential analyzer (RPA) are applied to measure the plasma parameters. The results show that compared to the single-antenna, the dual-antenna yields higher electron density, electron temperature, and ion energy. The measurements from the rf I–V probe indicate that the power coupling efficiency for the dual-antenna is about 2.6 times higher than that for the single-antenna. The plasma potential drop in the plume of the DMPT is the reason for the formation of ion beam. The neutral gas temperature is measured by rovibrational ban matching of the first negative band system of ionic nitrogen (N2+) for operating powers of 20 W up to 100 W. The total thrust of the DMPT has been calculated by the sum of the ion thrust and the neutral gas thrust. The total thrust at 100 sccm argon flow rate and 100 W rf power is ∼2.23 mN, which indicates an up to 168% thrust gain compared to the cold gas thrust, and a significant 11% total thrust is attributed to the ions’ electrostatic acceleration. The specific impulse and thruster efficiency at the above experimental conditions are ∼76 s and ∼0.8%, respectively. These initial results show that the dual-antenna scheme has better performance and is more promising than the traditional single-antenna design for electrodeless micro-electric propulsion. This novel and efficient micro plasma thruster is particularly useful for cubic satellites and scientific experiments in space (such as gravitational wave detection) which require gesture and orbit control of great precision.

DIMENSIONAL ANALYSIS AND EXPERIMENTAL DESIGN FOR PREDICTING THE CALCULATION OF THE VALUE OF THE TORQUE COEFFICIENT ON PROPELLER B-SERIES, CASE STUDY OF B3-50 AND B5-80

Experimental design is a fairly old method of statistically analyzing an experimental prediction. This is used to replace a fairly old system as well, namely in the form of a trial and error method. Because with this method the response results approach from a study can be predicted statistically. In this study, we will calculate some torque values of a propeller on a displacement ship type. Where the ship's operational displacement ship runs on a Froude number below 0.25, for that the Wageningen B-series propeller type is very suitable for this ship. Furthermore, dimensional analysis is carried out with variables that affect propeller performance and uses multivariate combination calculations. The results of the study show the regression equation between the KQ values of the B-series propeller data and the regression formula with the equation Y = 0.9916x + 0.000835 with the value of R2 being 0.9931. so we try to apply an experimental design method to be validated with the polynomial results of the B-series propeller on blades 3 to 6, so that the statistical method of this experimental design is up-to-date in propulsion design calculations.

Neutronic Evaluation and Optimization of the Centrifugal Nuclear Thermal Rocket Concept

The centrifugal nuclear thermal rocket is a concept for a liquid-fueled nuclear system that would allow for a much higher specific impulse than the more traditional solid-fueled nuclear thermal propulsion designs. Although some preliminary neutronics analyses have been done on conceptual designs, this work seeks to perform a more systematic analysis and optimization of design parameters and to investigate additional neutronics properties such as power distributions and reactivity coefficients. This work used OpenMC for neutronics analysis and Dakota for the parametric study and optimization. Inter- and intra-fuel element power distributions were calculated, and a strong radial dependence was noted within fuel elements that may pose a challenge to thermal constraints. A positive moderator temperature coefficient of 3.78 0.16 pcm/K was calculated for the reference model, which may pose a challenge for system design and control. The optimization study of reflector size, fuel spacing, fuel mass, and fuel element radius indicated many trade-offs in the design considerations, and that the baseline model can be significantly improved in all respects. Positive reactivity feedback can be minimized by reducing moderation, and peaking factors can be reduced by limiting the amount of fuel per fuel element, which also minimizes the system mass.

Details study on the kinematic characteristics of manta ray section in flapping motion and exploring its application in wave glider propulsion system

It has always been a human challenge to inspire natural configurations and phenomena and benefit from their merits in improving the performances of man-made proposed aero/hydro vehicles. For example, the manta rays are known for their great swimming performances. To design and fabricate an underwater robot based on the manta ray geometry and its kinematic characteristics, it is important to initially study its hydrodynamic behavior and possibly arrive at some key design parameters, which can remarkably help to figure out an optimum geometry with high swimming performances. The main objective of this study is to focus on the merits of gliding motion inspired by the manta ray fish considering the real sea conditions. In this regard, two wave-glider configurations with specific submersible geometries are selected to practice the bases of this objective. They are the manta-glider, which has a complicated 3D configuration representing the real manta ray swimming behavior, and the wing-glider, which has much simpler configuration constructing from a flat and uniform wing span shape. The 3D unsteady incompressible Navier-Stokes equations are numerically solved to simulate the gliding motion performances of these two gliders. The results show that the maximum efficiency of manta-glider model is ηmax = 50 %, which is much higher than that of the wing-glider with ηmax = 36 %, within an operational range with a relatively constant significant wave height (SWH). Alternatively, the wing-glider efficiency is about 5 % higher than that of the manta-glider in cases with non-constant SWH values. Irrespective of their efficiencies, the interesting outcome of this study is that the manta-glider model shows fewer fluctuations and performs more stable conditions than a simplified glider model in energy-absorbing applications. Considering the achieved outcomes, this work also suggests a simple guideline, which is so beneficial to arrive at a suitable wave glider propulsion design.

Integrated design of solar thermal propulsion system for microsatellite with liquid ammonia as propellant

This paper presents a design of solar thermal propulsion (STP) system for microsatellite with liquid ammonia as propellant. The system was equipped with two concentrators, which were respectively placed in the tank and thrust chamber for propellant supply and heating. A platelet heat exchanger was adopted to heat the propellant in the chamber, and the fluid–solid coupling effect between the wall and the gas was considered. Meanwhile, the effects of satellite mass, initial orbit, nozzle size and target temperature on the performance of STP system were analyzed. The results show that for microsatellites with a total mass of 100 kg, the STP system can fully heat the propellant to more than 2050 K, generate an intermittent thrust of about 26 N, and enable the satellite to obtain a velocity increment of more than 1470 m/s within 19 days, consuming only 42 kg of propellant, which can directly meet the transfer mission from the geostationary transfer orbit (GTO) to the geostationary orbit (GEO). The maximum velocity increment could reach more than 1950 m/s when the propellant was completely consumed; Changing the mass and initial orbit of the satellite will not affect the thrust and specific impulse. Satellites with smaller mass will spend less time and propellant during orbit transfer. The lower is the perigee height of the initial orbit, the greater is the propellant consumption, while the shorter is the time of orbit transfer; The reduction of nozzle throat size and target temperature will lead to the increase of specific impulse and the decrease of orbital transfer time, but the reduction of thrust.

Numerical investigation of heat transfer characteristics of moderator assembly employed in a low-enriched uranium nuclear thermal propulsion reactor

The design of a nuclear thermal propulsion (NTP) reactor based on low-enriched uranium (LEU) requires additional moderator elements in the core to physically meet the critical requirements. This design softens the core energy spectrum and can provide more thermal neutrons for the fission reaction, but the heat transfer characteristics between the fuel and moderator assembly are more complex. Aiming at the typical LEU unit design, the heat transfer mathematical model is established using the principle of heat flow diversion and superposition. The model adopts the heat transfer relationship based on STAR-CCM+ simulation rather than the empirical expression used in the past literature to improve the applicability of the model. The heat transfer coefficients in the proposed model are evaluated under different Reynolds numbers and thermal power. The deviations between the proposed model and CFD simulation are analyzed. The results show that the calculation of the heat transfer coefficient between the proposed model and the CFD simulation maintains a good consistency, most of which are within 10%. It may provide a reliable and conservative temperature estimation model for future LEU core design.

Form Factor and Wake Fraction of Bulky Trimaran Hull Using CFD

The value of form factor (1+k) and wake fraction significantly influence the ship propulsion design, including trimaran vessel. This paper presents the form factor and wake fraction of a single screw bulky trimaran using CFD. The model vessel is 1.92 m trimaran with scale to the actual vessel is 31.25 and evaluated in the range of Fn 0.1 to 0.2 based on ITTC recommendation. The results show that the form factor of the bulky trimaran is 1.433, which is close to the NPL series Trimaran value. The wake fraction was evaluated in two model speeds, 1.43 knot, which represent low speed and 6.26 knot which means high speed. The results show that the wake fraction pattern is similar to a single propeller vessel with the wake’s peak at 12 o’clock with the maximum value of wake around is 0.1.

Hybrid Power Supply for Take-off and Landing in Commercial Aircraft

Abstract: Hybrid is a viable technology to improve efficiency with respect to its uniqueness. It is the solution to use less fuel in an aircraft and to reduce the economic cost. Because the current state of our fossil fuels makes it unlikely that we will be able to fly an aircraft in the future, hybrid technology was developed to reduce fuel consumption. In this system, the amount of fuel used for takeoff, climb, and cruise can be bypassed using electric engines. The working principle is based on the electric engines and the batteries (lithium-ion). In the present, we have seen a propulsion design that can be used without any hassles and minimizes both the cost and the amount of fuel consumed. Because the Magni650EPU electric motor was the most compatible with the project, it was chosen. The goal was to improve fuel efficiency as well as hybridization. Keywords: Hybrid technology, fossil fuel, electric engine, Magni650EPU, lithium-ion battery.

Prediction of the Ultra-Large Container Ships' Propulsion Power at the Initial Design Stage

Container ships represent the fastest growing segment of maritime transport. The need to reduce unit transportation costs and environmental impact has led to development of the most capacious ultra-large container ships operating on the world's major shipping routes. A representative database of ultra-large container ships was created and further subdivided according to the main technical parameters. Using a simple cubic regression model, based on the least squares method, an equation, compliant to the general propeller law, was developed to predict the propulsion power of ultra-large container ships as a function of their sailing speed. The results obtained using the developed equation should be sufficiently close to the results of the exact verification calculations at the technical design stage. Then this prediction would find application in the design of both main propulsion, as well as waste heat and cold recovery systems.

Flow Separation Evaluation on Tubercle Ship Propeller

Propeller design for ship propulsion is important based on efficiency and power output. Advanced propeller design has been proposed in recent research, such as the tubercle propeller. The modified propeller on the leading edge with a tubercle-like design has been improved. Moreover, some evaluation has been studied on the design and performance. In the present study, the tubercle design on the leading edge is evaluated, which focuses on the flow separation effect developed by the tubercle shape. A computational fluid dynamic (CFD) model is compared between the normal and tubercle leading edge. The flow total pressure, Reynold number velocity, and power surface acoustic are evaluated. The flow separation is generated in the leading edge due to the tubercle shape. Moreover, the tubercle shape reduces the total pressure at the propeller blade, especially at the edges. It also increases the Reynold number velocity at the surface due to the flow separation. However, the flow separation decreased the power acoustic surface, which means it lost some power on the propeller.