Propulsion System Research Articles

Experimental Study on a Liquid Hydrogen Tank for Unmanned Aerial Vehicle Applications

A lightweight, 12 L liquid hydrogen fuel tank has been designed, fabricated, and tested with the aim of optimizing boil-off rates while minimizing the weight of a complete propulsion system intended to be integrated into an unmanned aerial vehicle. After looking at several different insulation schemes, the system was optimized as two concentric, lightweight titanium cylinders with high vacuum and multilayer insulation in between. The thickness of the multilayer insulation and the design of support structures were optimized to reduce the overall weight of the tank. This paper focuses on characterizing the boil-off rate of a small liquid hydrogen tank in relation to ambient temperature and fuel level. Additionally, it addresses the analysis of the instrumented transfer line between the reservoir and the operating fuel cell, presenting pressure and temperature measurements for each component of the transfer line. The efficiency of the heat exchanger under natural and forced convection is also discussed. The key contribution of the experimental campaign lies in demonstrating an average boil-off rate of 19.5 g/h over 45 h. This significantly surpasses the limits of ultra-long-range flight achievable with alternative electric energy sources. Furthermore, the paper highlights the importance of the variable boil-off with time and its impact on aircraft performance.

Cost-Benefit Analysis of converting vintage cars into EVs in India

Overview The following research paper attempts to analyses the viability of retrofitting old car models to electric cars in India. The increasing global problem of climate change and the developments in the area of electric cars make the concept of rebirth of old cars into EV’s a perfect marriage of youth into age. India with its tradition of having presence of vintage cars from quite some time can quite rightly wish for such a change. As it is this research aims to gather what one stands to gain both financially and non-financially by converting old model cars to EVs, PHEVs some of the questions included are; feasibility of the idea, cost, and its market. Purpose and objectives of the study The primary objective of this work is to provide the systematic analysis of the potential costs for the implementation of the change of the old generation vehicles to the electric propulsion system with regard to the initial capital outlay and recurrent costs and subsidies in India. Thus, the study seeks to also determine the prisms that underpin, the benefits in such conversion in terms of; Environmental gains for instance emission of carbon, economical gain such as cost of fuel, and the; social gain which is conservation of vintage cars. In this paper therefore, the authors endeavor to provide what they hope will be a useful analysis of the cost and issues involved in retrofitting old cars to make them electrically propelled, with a view to helping owners, businesses and governance institutions to make the right decision regarding this innovation. Its objectives are to find out if the benefits of environmental and economic nature will outweigh the costs and whether there is a market for remanufactured old model electric cars. Besides, this work will examine the factors that may be thought to slow this trend in the future such as technicalities, law demands and customers’ perceptions. This research assumes importance especially at this time in relation to India where there has been earlier association with cars of certain years of manufacture and especially the government to support its desire to champion massive usage of EV to tackle problems of pollution and use of fossil fuel. Therefore, this study will also contribute to the existing discussion on the gap of increasing the shares of sustainable transportation keeping the historic vehicles intact. The results could also include directions for the policymakers and the automobile enthusiasts who wishing to proceed with the change over from classic autos to electric automobiles as a possible and viable process.

The effect of spatial non-uniformity on multiple transient modes of detonation onset in a three-dimensional channel

The study of the transient combustion modes is one of the key topics when considering the safety of space flights. Control of detonation onset has a dual application. First, the search for ways to prevent detonation modes in case of accidental fuel releases for fire safety issues of launch systems and the avoidance of accidents with rocket engines at a launch site and in near-Earth space. Second, the study of detonation and the possibility of using it to create propulsion systems based on detonation combustion of fuel. The paper shows the effect of the presence of spatial non-uniformities on the promotion of detonation in the chamber. Various geometries with and without obstacles and cavities are considered. It is demonstrated that the presence of obstacles accelerates the transition to the detonation process on the one hand, but on the other hand the presence of obstacles in combustion chamber could be the cause of incidental uncontrolled ignition, which ruins stable operation of an engine. The results of theoretical studies of the working cycle of the combustion chamber of a pulsed detonation engine are presented. Theoretical estimates for thrust characteristics are obtained.

Hierarchical Control Strategy for the Hybrid Electric Propulsion System of a Flying Car With Engine Start-Stop System and Dynamic Coordination

Hierarchical Control Strategy for the Hybrid Electric Propulsion System of a Flying Car With Engine Start-Stop System and Dynamic Coordination

Computational investigation of both geometric and fluidic compressible turbulent thrust vectoring, using a Coanda based nozzle

This study addresses the challenge of enhancing aircraft maneuverability, particularly for vertical landing and takeoff, focusing on the fluidic aerial Coanda high efficiency orienting jet nozzle that employs the Coanda effect to achieve thrust vectoring. This research advances understanding of the interplay between geometric and fluidic factors in thrust vectoring. Stationary, turbulent, and compressible flow conditions are assumed, employing Favre-averaged Reynolds-averaged Navier–Stokes approach with the standard k-ε model. Computational solutions were obtained using a pressure-based finite volume method and a structured computational grid. The key findings include thrust vectoring enhancement due to an increase in the total mass flow rate, septum position (at no shock wave-related issues), and Reynolds number. In addition, shock wave formation (at specific mass flow rates and septum positions) considerably affects thrust vectoring. These insights are crucial for optimizing Coanda-based nozzle design in advanced propulsion systems, including in unmanned aircraft vehicles.

Analytical model of a Hall thruster

Hall thrusters are one of the most successful and prevalent electric propulsion systems for spacecraft in use today. However, they are also complex devices and their unique E×B configuration makes modeling of the underlying plasma discharge challenging. In this work, a steady-state model of a Hall thruster is developed and a complete analytical solution presented that is shown to be in reasonable agreement with experimental measurements. A characterization of the discharge shows that the peak plasma density and ionization rate nearly coincide and both occur upstream of the peak electric field. The peak locations also shift as the thruster operating conditions are varied. Three key similarity parameters emerge that govern the plasma discharge and which are connected via a thruster current–voltage relation: a normalized discharge current, a normalized discharge voltage, and an amalgamated parameter, α¯, that contains all system geometric and magnetic field information. For a given normalized discharge voltage, the similarity parameter α¯ must lie within a certain range to enable high thruster performance. When applied to a krypton thruster, the model shows that both the propellant mass flow rate and the magnetic field strength must be simultaneously adjusted to achieve similar efficiency to a xenon thruster (for the same thruster geometry, discharge voltage, and power level).

The Dynamic Stability and Performance Implications of Piston-to-Turboprop Engine Modernization of a Light Aircraft for General Aviation

ABSTRACT This paper explores the influence of engine modernization on the dynamic stability and performance of a general aviation aircraft. Utilizing an integral mathematical model, the study conducts a comparative analysis of the I-23 Manager piston-engine aircraft and its modified I-31T turboprop version, examining changes in aircraft dynamics depending on the power plant type. The modernization necessitated a redesign of the nose section of the fuselage, resulting in alterations to the external shape and flight properties of the aircraft. The research evaluates various dynamic stability parameters, including phugoid, short period, Dutch roll, roll, and spiral modes, under different flight conditions. Results indicate minimal changes in aerodynamic characteristics due to the engine type, yet significant improvements are observed in efficiency, noise reduction, and operational costs. The impact of the propulsion unit on the dynamic stability of the light aircraft was assessed as insignificant, suggesting that the strategy of modernizing an existing piston-driven aircraft by switching to a turboprop drive is indeed promising. With appropriate initial design assumptions, a modern turbine aircraft with strong flight qualities can be efficiently modernized in this way, without compromising the good flying properties of the existing plane. The outcomes are validated against flight tests, reinforcing the viability of integrating more sustainable and efficient propulsion systems into light aircraft. This study may therefore inform future design and regulatory decisions, providing a perspective on the implications of engine upgrades in the general aviation sector.

Mars 2020 Descent Stage Integrated Propulsion Subsystem: Changes and Flight Performance

On February 18, 2021, NASA’s Mars 2020 mission successfully landed the Perseverance rover in Jezero Crater, the heaviest interplanetary rover ever built, on the surface of Mars. Following up on the successful entry, descent, and landing of the Curiosity rover of the Mars Science Laboratory mission in August 2012, the Mars 2020 mission Descent Stage Propulsion System was a build-to-print sequel. The Mars 2020 Descent Stage Propulsion System had a few minor low risk changes based on the flight performance of the Mars Science Laboratory System to improve performance. The in-flight performance of the Descent Stage Propulsion System was consistent with expectations with the exception of apparent higher than expected delivered thrust from the Mars Lander Engines, which occurred on both the Mars 2020 and the Mars Science Laboratory missions. The Descent Stage Propulsion System completed its mission with significant capability margin with respect to thruster life, maximum delivered thrust, and available propellant at touchdown.

Impact of Future Low-Emissions Combustor Technology on Acoustic Scaling Laws

A first-of-its-kind examination of broadband noise associated with a far-term advanced low-emission aerocombustor concept is presented. Because of design trends and expected cycle changes for future aircraft propulsion systems, noise generated by sources in the combustor are expected to become of increasing significance for airport-community noise. The paper assesses the impact on legacy semi-empirical noise-prediction methods from the expected radical departures from current combustor operating conditions and designs, such as fuel/air distribution and flame anchoring techniques. Such methods are essential in system-level noise assessments at the preliminary design stage for advanced air transports to assure that overall environmental goals are met. Detailed unsteady pressure measurements, obtained in a fundamental combustion noise experiment using a combustor rig at relevant pressures and temperatures are analyzed. In addition to an advanced far-term low-emissions concept, a reference configuration with the test section arranged to model a modern combustor sector was also studied. For the test rig in the current-generation configuration, the measured broadband acoustic data are reasonably well described by the acoustic-power scaling laws used in legacy semi-empirical noise-prediction methods. For the future-advanced configuration, the legacy scaling laws, with some notable exceptions, provide correct trends, but with much less accuracy.

Enhanced Calibration and Performance Prediction Method for Entire Propulsion System of eVTOL UAV

Enhanced Calibration and Performance Prediction Method for Entire Propulsion System of eVTOL UAV

Estimation of the clutch pressure basing on reduced order model of the hydraulic actuator system

Estimation of the clutch pressure basing on reduced order model of the hydraulic actuator system

Research on Classification Maintenance Strategy for More Electric Aircraft Actuation Systems Based on Importance Measure

In this paper, a practical maintenance algorithm is proposed to improve the reliability of actuation systems and their components, specifically addressing the consistency degradation caused by faults in the symmetric actuation system components of more electric aircraft (MEA). By integrating important measures with traditional genetic algorithms, the accuracy of the algorithm is improved. Prior to maintenance, a reasonable classification of components is built to mitigate the adverse effects of extreme fault conditions on the algorithm. This approach improves both the effectiveness and efficiency of the algorithm, rendering the overall maintenance strategy better suited for real-world needs. Finally, comparative simulations confirm the algorithm’s superior performance in reliability improvement, demonstrating its substantial contribution to the field of MEA maintenance and reliability.

Electromagnetic Plasma Reactor: Fermionic Derivation Tools

From the developed theories around of an electromagnetic plasma reactor designed and controlled through geometrical invariants has been demonstrated the existence of derived products from electromagnetic plasma as are phonons, fermions, ions, free electrons and protons, magnetic and electric drifts, which can be used as complement or development part of the electromagnetic propulsion system where the fermion flow can produce a ionic force that could be used as propulsion force considering shock waves produced with an electric field on these ions. Likewise, experimentally and considering direct current and voltage in a constant regime, has been detected as ionic wind which carries fermion products to be used too in the possible electromagnetic propulsion. These are other products proposes of previous works. Likewise, through of a caption and detection camera, is measured the electromagnetic properties of the ionic flow of the space derived from the electromagnetic plasma, and is proposed a curvature energy signal of magnetic nature to measure the force and control the electromagnetic plasma and its ionic flow.

Xenon fluid state model and evaluation of working medium in satellite electric propulsion system

Xenon, the working medium of satellite electric propulsion system, is easy to enter the supercritical state, and does not follow the ideal gas equation of state in filling and in-orbit application. The error of fluid state and parameter evaluation of xenon is large. In view of this difficulty, the working fluid state test system and test method of xenon were established. The saturation vapor pressure, gas phase PVT and supercritical PVT characteristics of xenon were tested. A new saturation vapor pressure equation of xenon was established. The relative deviation between the saturated vapor pressure test results and the NIST equation is less than 0.2 %. The Helmholtz equation established on the basis of xenon experimental data has a high accuracy, and the deviation from the experimental data is less than 0.5 % within 273 K–358 K. In 358 K–373 K, the deviation from the test data is better than 0.05 %, and the second dimension coefficient is used to prove the accuracy and reliability of the model, which provides a state model for satellite xenon filling and in-orbit application.

Performance and optimization evaluation for integration of sCO2 power system into the aircraft propulsion system

The aviation industry accounts for part of the CO2 emissions contributing to climate change. The industry has established a target to reduce 2050 net aviation carbon emissions by 50 % relative to 2005 levels. With this in mind, waste heat recovery is a key pathway to achieve reduced emissions and improve system efficiency. The waste heat may potentially be converted to electric power using a supercritical CO2 Brayton power cycle. The sCO2 power system offers the advantage of compactness owing to the high working fluid density, which is an important consideration for aircraft performance. The present work focuses on the integration of the sCO2 power system into the aircraft propulsion system and evaluation of its performance. Detailed optimization of the sCO2 waste heat system will be evaluated with a focus on cycle efficiency and net power under different operating conditions, including ground, takeoff, climb, cruise, and landing operations. The study is divided into two parts with two different turbofan engines, one with a nominal thrust of 30 kN and the other with a nominal thrust of 9 kN. The first part shows the effect and operation of the waste heat recovery unit under the different operating conditions. The second part is focused on cycle optimization and performance evaluation. The results demonstrate the potential of waste heat recovery during a range of operational conditions. The sCO2 cycle efficiency can reach between 25 and 39 % (depending on aircraft engine) with net power output in the range of 100 to 260 kW.

A cost-effective linear propulsion system featuring PMEDW for HTS maglev vehicle: design, implementation, and dynamic test

Since 2021, the first high-speed, high-temperature superconducting maglev engineering prototype has proven its practical feasibility. However, the pressing need to mitigate the high costs of the current linear synchronous motor (LSM) technology remains paramount. This study aims to tackle this issue by introducing a novel, cost-effective propulsion way featuring the PMEDWs, optimizing its specifications, studying electromagnetic characteristics, fabricating a physical prototype, and conducting line tests to confirm application feasibility. Firstly, the conceptual prototype is introduced, outlining its functionality and principles. Subsequently, employing dynamic simulation models, structural specifications are optimized, and electromagnetic characteristics are evaluated. Afterwards, a comprehensive HTS maglev prototype weighting 1200 kg equipped with four PMEDWs and measurement system is designed and fabricated. Finally, validation of the simulation model effectiveness is conducted using a dedicated test rig. Dynamic line tests along a 165-meter line measure the performance metrics of the speed, levitation and propulsion gap, lateral and vertical accelerations, and propulsion and guidance forces, and maximum operation speed of 3. 03 m/s at n = 500 rpm. This study implements the physical prototype and dynamic testing of the PMEDW propulsion system, and confirms its feasibility for the first time, and the estimated cost is approximately one-tenth of the existing LSM motors in the 165-m test line. This technology promises significant innovation in linear propulsion methods, offering an economical alternative for Maglev vehicles.

Experimental study and performance analysis of a dual-mode space propulsion system pressurized by electric pump

This study presents a new dual-mode propulsion system that utilizes an electrically pumped hydrogen peroxide and kerosene supply system, specifically designed for advanced spacecraft orbit and attitude control. The system incorporates two distinct electric pumps, one for hydrogen peroxide and another for kerosene, each engineered to optimize the propellant feed for the orbit control and attitude control engines. This configuration enables precise propellant management and thrust control, which are critical for the stringent demands of modern space missions. The dual-mode capability of the propulsion system allows for the use of hydrogen peroxide both as a monopropellant in the attitude control engine and as an oxidizer in combination with kerosene in the orbit control engine. This approach simplifies the propulsion architecture while maximizing the efficiency and utility of hydrogen peroxide as a propellant. The electric pumps are essential in providing high-pressure propellant delivery, which is necessary to achieve the desired combustion characteristics and thrust parameters. Performance evaluations of the propulsion system demonstrated significant results. The orbit control engine achieved a combustion chamber pressure of 5.9 MPa and a combustion efficiency of 98.42 %. The attitude control engine, operating at a peak pressure of 4.9 MPa, exhibited a stable pulsative mode, maintaining consistent pressure levels throughout its operational cycle. These performance metrics highlight the effectiveness of the electric pump technology in enhancing propulsion system responsiveness and efficiency. This propulsion system is expected to improve spacecraft maneuverability and reduce operational costs, making it suitable for long-duration space missions.

An efficient multi-fidelity simulation approach for performance prediction of adaptive cycle engines

Adaptive cycle engine (ACE) with multi-stream, modulated bypass ratio, and high-thrust/high-efficiency mode provides the capability of multiple mission adaptation for the next-generation aviation propulsion system. The low-fidelity zero-dimensional (0D) performance simulation method is commonly adopted in conventional engines such as turbofan and turbojet. However, it is hard to accommodate well to ACE with complex variable geometry schemes and strong interaction between components. This paper presents an efficient multi-fidelity simulation approach, often referred to as component zooming, for predicting the performance of ACE with the three-stream configuration. The one-dimensional (1D) mean-line models of the adaptive fan and low-pressure turbine (LPT) are integrated into the 0D ACE model by the iteratively-coupled method. The performance predicted by the multi-fidelity ACE models with different component zooming strategies is compared. The maximum deviations of thrust, specific fuel consumption, turbine inlet temperature, and bypass ratio between the 0D/1D Adaptive Fan/1D LPT coupled model and 0D ACE model are −10.8%, −4.4%, −5.4% (−75 K), and 1.6%, respectively, which are considerable and non-negligible for the application in the design stage of ACE. The computing time of all the multi-fidelity models is less than 2 minutes. The effects of the key aerodynamic parameters of the adaptive fan and LPT on the engine performance are also evaluated. The proposed approach provides a generic and efficient solution for multi-fidelity ACE performance prediction with acceptable computing resource requirements and time cost, which is applicable in the engine conceptual and preliminary design stage.

Trajectory & maneuver design of the NEA Scout solar sail mission

The Near-Earth Asteroid Scout (NEA Scout) mission aimed to deliver a 6U CubeSat to a slow flyby of a Near Earth Asteroid using a solar sail as the primary propulsion system. NEA Scout was launched as a secondary payload aboard Artemis I, on November 16, 2022, but communication with the spacecraft was not achieved. This paper describes the target asteroid selection and the innovative trajectory and maneuver design for the NEA Scout mission, including cold gas maneuvers, multiple lunar flybys, solar sail thrusting, and design margins for solar sailing. The resulting trajectory design tools, solutions, and analyses are potentially applicable to future solar sail missions.

Proof of Concept of a New Revision Procedure for Ceramic Inlays of Acetabular Cups Using a Shape-Memory Alloy Actuator System.

The revision of ceramic inlays of acetabular cups is a challenging surgical procedure. The mechanical impact during the inlay extraction process can damage the ceramic or metal cup rim. To avoid these risks, a concept for a new revision procedure was developed. It is based on an actuator system, which allows a non-destructive release of the ceramic inlay. To integrate the actuator system, different design concepts of acetabular cup components were investigated, and an actuator based on shape-memory alloy (SMA) wires was developed. The process chain for the actuator, starting from nickel-titanium wires manufactured into the actuator geometry by laser welding and thermo-mechanical treatment for the shape setting process up to the functionality evaluation of the actuator system, was implemented on a laboratory scale. The new revision procedure is based on a phase transformation of the SMA wire actuator, which was obtained through two methods-applying an electrical current by an instrument and rinsing the wire with heated water. The phase transformation of the actuator resulted in a contraction between 3.2% and 4.3% compared to its length after pre-stretching and was able to release the ceramic inlay from the cup. Therefore, the developed actuator design and process chain is a proof of concept towards a new revision procedure for modular acetabular cups.