Propulsion Devices Research Articles

ON THE STABILITY OF MOBILE ROBOTS MOVEMENT WITH CABLE PROPULSION DEVICES

The movement of the platform of the underwater mobile robot with an excessive number of propulsion devices, clinging to the reservoir’s bottom, is considered. The task of determining the laws of the transition process, assessing its stability and quality indicators of control when establishing the specified relations between the efforts in the cables is studied.

Experimental investigation of a low-energy linear plasma propulsion device

This paper presents preliminary results for a new design of a pulsed linear plasma device that generates electromagnetic plasma propulsion. The current sheath dynamics and the plasma propulsion along an extension tube have been studied. Breakdown of helium gas occurs between coaxial electrodes when applying a high-voltage pulse. This paper presents measurements with a number of probes, as well as camera images of the plasma propagation. A plasma is ejected and fills a 40 cm length extension tube. Additionally, the measurements show that the length of the propelled plasma column and its intensity inside the expansion tube is increased by increasing the charging voltage, while the plasma propulsion current is decreased along the extension tube. It is noted that a lower critical time; 4.7 μs, is needed to ionize the gas and form the plasma current sheath.

Research progress on active thermal protection for hypersonic vehicles

Hypersonic vehicles with scramjet engine as propulsion devices is one of the most important developing trends in the aerospace field for both commercial and military application. The encountered huge aerodynamic heating and strong combustion heat release makes the thermal protection technology a critical issue. For the long run and for reusable purposes, an effective active other than a passive thermal protection method is required for the cooling process, mainly by including regenerative cooling, film cooling, transpiration cooling and their combinations. In this paper, the authors point out that the cooling resources are extremely limited for hypersonic vehicles. They define the “relative heat load” for the analysis of the active thermal protection for hypersonic vehicles. This paper presents a review of the research progress made on the active thermal protection method for air-breathing hypersonic vehicles in recent decades. It primarily covers the fundamental problems and recent advances, including regenerative cooling, film cooling, transpiration cooling, and combined cooling. A number of relevant aspects and remaining questions for each active cooling method are provided, including the basic flow and heat transfer mechanisms, the influencing factors and their effects, the progress in engineering application. Finally, summaries of each active cooling method, guidelines for their future development, and the authors’ view on the promising active thermal protection methods for future hypersonic vehicles are provided.

Ion beam diagnostic for the assessment of miniaturized electric propulsion systems.

An automated plume diagnostic system is presented for two-dimensional mapping of the ion beam produced by using miniaturized electric propulsion devices. The instrument is designed to operate with noble and reactive gases and consists of a semi-circular probe array with a unique angular distribution following a Gaussian shape for improved beam profile resolution. To demonstrate the operation of the diagnostic system, a series of experiments are conducted with a low-power gridded ion thruster using xenon and iodine propellants. The two-dimensional current density maps generated are used to calculate important beam properties for performance estimates, including the total ion current and the effective divergence angle, and we show how the measurements can be used to assess and optimize the design of ion optics for gridded ion thrusters. All current density measurements with the new instrument are corrected for secondary electron emission (SEE) due to ion bombardment, and using a separate, specially designed, electrostatic probe, we present the first measurements of the SEE yield for iodine ions impacting molybdenum and SAE 304 stainless steel surfaces.

Double layer formation and thrust generation in an expanding plasma using 1D-3V PIC simulation

Due to large particle exhaust velocity and specific impulse, electric propulsion systems have an edge over chemical propulsion for missions targeting regions outside the Earth's atmosphere. Stationary plasma thrusters and helicon plasma thrusters (HPTs) are commonly used electric propulsion devices for a space mission. In HPTs or expanding magnetic field plasma thrusters, plasma expands from the source region to the expansion region in an externally applied expanding magnetic field. Due to plasma expansion in such a magnetic field configuration, a current free double layer is found to form, which accelerates bulk ions, and a directional ion beam is generated, which causes thrust in the opposite direction. A Particle In Cell (PIC) solver with Monte Carlo Collision (MCC) scheme which resolves the axial direction and all three velocity degrees of freedom (1D-3V PIC-MCC) that captures the 2D spatial plasma expansion effect via a 1D flux conserving model is developed to simulate an argon plasma in an expanding magnetic field. Using the 1D-3V PIC-MCC solver, double layer formation due to plasma expansion, thrust generation, and optimization of thrust studies over a large parameter set, such as fill pressure of Ar, is presented. We compare our results with a particle loss model, which is commonly used as the simplest model for HPTs.

Aircraft Propellers—Is There a Future?

The race for speed ruled the early Jet Age on aviation. Aircraft manufacturers chased faster and faster planes in a fight for pride and capability. In the early 1970s, dreams were that the future would be supersonic, but fuel economy and unacceptable noise levels made that era never happen. After the 1973 oil crisis, the paradigm changed. The average cruise speed on newly developed aircraft started to decrease in exchange for improvements in many other performance parameters. At the same pace, the airliner’s power-plants are evolving to look more like a ducted turboprop, and less like a pure jet engine as the pursuit for the higher bypass ratios continues. However, since the birth of jet aircraft, the propeller-driven plane has lost its dominant place, associated with the idea that going back to propeller-driven airplanes, and what it represents in terms of modernity and security, has started a propeller avoidance phenomenon with travelers and thus with airlines. Today, even with the modest research effort since the 1980s, advanced propellers are getting efficiencies closer to jet-powered engines at their contemporary typical cruise speeds. This paper gives a brief overview of the performance trends in aviation since the last century. Comparison examples between aircraft designed on different paradigms are presented. The use of propellers as a reborn propulsive device is discussed.

직렬 다단 전극 구성에 따른 전계 분포와 이온풍 특성

Ionic wind propulsion system has less noise and is easier to miniaturize and has higher power ratio than the existing propulsion system. However, the amount of ionic wind that can be generated is small to apply as a single propulsion device. So, that is used as auxiliary propulsion device. In this paper, to improve maximum ionic wind speed which is limited by the breakdown voltage, the corona electrodes and induction electrodes were configured in series and the spacing between the primary and secondary corona electrodes was adjusted. Superposition of electric fields in series multi-stage configuration is increase rear electric fields strength. However, when the gap was smaller than a specific value, the electric field from the secondary corona electrode to the primary induction electrode was strengthened, thereby electric field strength of the front portion was greatly weakened. When the gap became more than a certain value, the decrease in electric field strength was saturated. So, ionic wind speed was measured most strongly at the first saturation interval.

Droplet Self-Propulsion on Superhydrophobic Microtracks.

Liquid transport (continuous or segmented) in microfluidic platforms typically requires pumping devices or external fields working collaboratively with special fluid properties to enable fluid motion. Natural liquid adhesion on surfaces deters motion and promotes the possibility of liquid or surface contamination. Despite progress, significant advancements are needed before devices for passive liquid propulsion, without the input of external energy and unwanted contamination, become a reality in applications. Here we present an unexplored and facile approach based on the Laplace pressure imbalance, manifesting itself through targeted track texturing, driving passively droplet motion, while maintaining the limited contact of the Cassie-Baxter state on superhydrophobic surfaces. The track topography resembles out-of-plane, backgammon-board, slowly converging microridges decorated with nanotexturing. This design naturally deforms asymmetrically the menisci formed at the bottom of a droplet contacting such tracks and causes a Laplace pressure imbalance that drives droplet motion. We investigate this effect over a range of opening track angles and develop a model to explain and quantify the underlying mechanism of droplet self-propulsion. We further implement the developed topography for applications relevant to microfluidic platform functionalities. We demonstrate control of the rebound angle of vertically impacting droplets, achieve horizontal self-transport to distances up to 65 times the droplet diameter, show significant uphill motion against gravity, and illustrate a self-driven droplet-merging process.

POLYMER PRECURSORS FOR CREATING GAS DISCHARGE CHAMBER FOR ELECTRIC ROCKET ENGINE

Electric rocket engines are widely used in space technology. Furthermore, at present, electric propulsion engines are also used as mid-flight engines for flights in interplanetary space. On modern spacecraft, the following types of electric propulsion are mostly used: SPT and grid ion thruster. When using these engines as sustainers, it is important is to increase the total power for obtaining the required thrust and specific impulse. With an increase in total power, the volume of the discharge chamber increases, which leads to technological difficulties in the manufacture of discharge chambers from ceramic materials. Thus, the task of finding alternative ceramic materials is relevant and necessary in the development of high-frequency ion thrusters. The article discusses the issues of creating a composite material based on woven quartz materials and organosilicon binder as a precursor filled with silicon nitride for the manufacture of gas discharge chamber (GDC) of high-frequency ion thruster (RFIT). By thermos-gravimetric analysis, a thermosetting binder, which meets the requirements of vibration resistance and electromagnetic permeability of GDC in the megahertz range, was selected. Based on the binder filled with silicon nitride powder, reinforced by quartz woven fabrics, manufactured GDC. The resulting product was tested as part of the laboratory electric propulsion device with a diameter of 100 mm and power of 200W.

Reconfigurable microbots folded from simple colloidal chains

To overcome the reversible nature of low-Reynolds-number flow, a variety of biomimetic microrobotic propulsion schemes and devices capable of rapid transport have been developed. However, these approaches have been typically optimized for a specific function or environment and do not have the flexibility that many real organisms exhibit to thrive in complex microenvironments. Here, inspired by adaptable microbes and using a combination of experiment and simulation, we demonstrate that one-dimensional colloidal chains can fold into geometrically complex morphologies, including helices, plectonemes, lassos, and coils, and translate via multiple mechanisms that can be varied with applied magnetic field. With chains of multiblock asymmetry, the propulsion mode can be switched from bulk to surface-enabled, mimicking the swimming of microorganisms such as flagella-rotating bacteria and tail-whipping sperm and the surface-enabled motion of arching and stretching inchworms and sidewinding snakes. We also demonstrate that reconfigurability enables navigation through three-dimensional and narrow channels simulating capillary blood vessels. Our results show that flexible microdevices based on simple chains can transform both shape and motility under varying magnetic fields, a capability we expect will be particularly beneficial in complex in vivo microenvironments.

Research of influence of the additional electrode on Hall thruster plume by particle-in-cell simulation**Project supported by the National Natural Science Foundation of China (Grant No. 51776047), the Key Project of the National Natural Science Foundation of China (Grant No. 51736003), the Civil Aerospace Pre-research Project (Grant No. D010509), and the Open Fund of Beijing Institute of Control Engineering (Grant No.

Hall thruster is an electric propulsion device for attitude control and position maintenance of satellites. The discharge process of Hall thruster will produce divergent plume. The plume will cause erosion, static electricity, and other interference to the main components, such as solar sailboard, satellite body, and thruster. Therefore, reducing the divergence of the plume is an important content in the research of thruster plume. The additional electrode to the plume area is a way to reduce the divergence angle of the plume, but there are few related studies. This paper uses the particle-in-cell (PIC) simulation method to simulate the effect of the additional electrode on the discharge of the Hall thruster, and further explains the effect mechanism of the additional electrode on parameters such as the electric field and plume divergence angle. The simulation results show that the existence of the additional electrode can enhance the potential near the additional position. The increase of the potential can effectively suppress the radial diffusion of ions, and effectively reduce the plume divergence angle. The simulation results show that when the additional electrode is 30 V, the half plume divergence angle can be reduced by 18.21%. However, the existence of additional electric electrode can also enhance the ion bombardment on the magnetic pole. The additional electrode is relatively outside, the plume divergence angle is relatively small, and it can avoid excessive ion bombardment on the magnetic pole. The research work of this paper can provide a reference for the beam design of Hall thruster.

Comprehensive Performance Analysis for the Rotating Detonation-Based Turboshaft Engine

The potential advantages of rotating detonation combustion are gradually approved, and it is becoming a stable and controllable energy conversion way adopted to the propulsion devices or ground-engines. This study focuses on the rotating detonation-based turboshaft engine, and the architecture is presented for this form of engine with compatibility between the turbomachinery and rotating detonation combustor being realized. The parametric performance simulation model for the rotating detonation-based turboshaft engine are developed. Further, the potential performance benefits as well as their generation mechanism are revealed, based on the comprehensive performance analysis of the rotating detonation-based turboshaft engine. Comparisons between the rotating detonation turboshaft engine and the conventional one reveal that the former holds significant improvements in specific power, thermal efficiency, and specific fuel consumption at lower compressor pressure ratios, and these improvements decrease with the increase of compressor pressure ratio and increase as turbine inlet temperature increases. The critical compressor pressure ratio corresponding to the disappearance of specific power improvement is higher than that corresponding to the disappearance of thermal efficiency and specific fuel consumption. These critical compressor pressure ratios are positively correlated with flight altitude and negatively correlated with flight velocity. The conductive research conclusion is guidable for the design and engineering application of rotating detonation-based engines.

Modelling of maneuvering of the ship equipped with two azipods

Wide development of the Northern Sea Route is one of the main national projects of the Russian Federation. Solution of this large-scale problem is impossible without new types of ships, which are capable of working all year round among ice of polar latitude. These vessels are designed for different purposes, so that they are characterized by stronger hulls of ice class and new types of propulsion device – azipods, in other words – screw-steering columns. Rotating of azipods along vertical axis allows to direct propulsive force in arbitrary direction, which makes it possible to stop using rudder and move more efficiently. For example, proceed forward with stern of the ship. Ships with two azipods are of special effectiveness. With wide operation of new types of propulsion devices, it becomes necessary to include their particular mathematical models in general model of the vessel. This as well applies to azimuthal propulsion devices, known as screw-steering columns. Model becomes more complicated when the ship is equipped with two azipods, which influence each other during application in a particular way. The practicable way of research of such ships’ work is their mathematical modelling, which includes modelling of the hull of the ship, as well as the azipods the ship equipped with. Exactly this model is described in this research. The vessel with displacement of about 36000 tons is equipped with two azipods. Hull is described by the model in shifts, work of every azipod – by Hoffmann algorithm. Basic value of propulsion force of every screw of azipod before its turn is calculated with Lammeren curve of screw force.

Spatial measurement of axial and radial momentum fluxes of a plasma expanding in a magnetic nozzle

Spatial profiles of axial and radial momentum fluxes of a plasma expanding in a magnetic nozzle is revealed by using a momentum vector measurement instrument located downstream of a radiofrequency plasma source, where the radial and axial forces exerted to the detector plate facing the source side are independently, directly, and simultaneously obtained. It is shown that a conical structure having high electron temperature and plasma density is significantly responsible for the axial momentum flux, which corresponds to the thrust in an electric propulsion device. The radially outward momentum flux is detected at the outer region of the conical structure, where the electron pressure gradient is formed; implying that the ions are radially accelerated by an electric field. The increase in the radially integrated axial momentum flux along the axis is demonstrated, where the gain of the axial momentum flux occurs at the radially peripheral region of the plasma expanding along the magnetic nozzle.

Darcy flow of polymer from an inclined plane with convective heat transfer analysis: a numerical study

An analytical model is developed to study the Darcy flows in viscoelastic convection from an inclined plate as a simulation of electro-conductive polymer materials processing with Biot number effects. The Jeffery’s viscoelastic model describes the non-Newtonian characteristics of the fluid and provides a good approximation for polymers, which constitutes a novelty of the present work. The normalized nonlinear boundary value problem is solved computationally with the Keller Box implicit finite difference technique. Extensive solutions for velocity, surface temperature, skin friction and heat transfer rate are visualized numerically and graphically for various thermophysical parameters. Validation is conducted with earlier published work for the case of a vertical plate in the absence of non-Newtonian effects. The boundary layer flow is accelerated with increase in Deborah number, whereas temperatures are decelerated slightly. Temperatures are boosted with increase in inclination parameter, whereas velocity is lowered. A reverse trend is seen for increasing mixed convection parameter. Increase in Biot number enhances both velocity and temperature. Increasing Darcy number is found to enhance velocity, whereas it suppresses temperature. This particle study finds applications in different industries like reliable equipment design, nuclear plants, gas turbines and different propulsion devices.

Improvement of Microcathode Arc Thruster Lifetime by Deposition of Boron-Containing Coating

Boron-containing coatings are actively used to improve the surface properties of mechanical parts of various devices and cutting tools. In this Paper, we demonstrate that deposition of boron-containing coatings by direct electron-beam evaporation of a boron target with a fore-vacuum plasma-cathode electron source can be used to substantially (by a factor of approximately 6–17) improve the lifetime of miniature (centimeter-sized), low-power (several watts), micronewton thrust level microcathode arc thrusters. Such improvement is a result of slowing down the interelectrode film degradation that occurs after numerous arc pulses. This improvement is observed after applying a hard (resistant to shock by plasma in a single pulse) sputter-resistant (able to maintain its protective properties for numerous pulses) boron coating on the interelectrode dielectric (alumina ceramic). This finding opens up a new way to improve the performance and lifetime of low-power vacuum-arc based propulsion devices for small satellites.

CI-MBPT line strengths and atomic probabilities for some transitions of neutral iodine

Iodine is a promising alternative to expensive xenon as a propellant for electric propulsion devices. Iodine optical spectroscopy is a valuable diagnostic tool for optimization of the iodine propellant. Recently, some measurements have been conducted with cells containing iodine plasma, and iodine atomic absorption at several wavelengths (911, 906, 206 and 1315 nm) was measured with a Ti:sapphire laser. Motivated by these experiments and future applications, we have calculated line strengths and atomic probabilities for the transitions between different types of 5s25p5, 5s25p46s, 5s25p46p and 5s25p45d states of atomic iodine, using configuration-interaction many-body perturbation theory. Since experimental transition data for atomic iodine are only available for a relatively small number of transitions, we also performed calculations for the bromine atom, to further validate our approach. We found good agreement between our theory and available experimental data for both elements in most cases. Therefore, we believe that our predicted line strengths and transition probabilities are quite reliable and will be useful for iodine spectroscopy.

Magnetically-levitated thrust stand for evaluating 6-component thrust vector of 1-N class onboard propulsion devices

This paper describes a magnetically-levitating thrust stand for the measurement of the six-component thrust vector of onboard propulsion devices. Conventionally, the thrusts of such devices that yield small thrust-to-weight ratios have been measured using pendulums, which can reduce the influence of gravitational force on the thrust measurement. The conventional thrust stand successfully measures the thrust with enhanced accuracy; however, the thrust vector is difficult to evaluate as the thrust vector measurement requires a higher degree of freedom for the pendulum. Hence, the authors propose the use of magnetic levitation of the thruster using voice coil motors, which have the appropriate characteristics for small thrust evaluation: linearity and responsiveness. A 1-N class prototype was designed to show that the six-component thrust vector can be measured using the magnetically-levitating thrust stand. The prototype evaluated 0.5-N class six-component thrusts, whereas the conventional pendulum-type thrust stands were unable to determine the thrust vectors. Moreover, the calibration shows that the thrust stand accurately evaluated the reference thrust vector with a coefficient of determination higher than 0.988.

Aircraft Propellers, an Outdated Innovation?

The race for speed ruled the early Jet Age on aviation. Aircraft manufacturers chased faster and faster planes in a fight for pride and capability. In the early 1970s, dreamed that the future would be supersonic, but fuel economy and not acceptable noise levels made that era never came. After the 1973 first oil crisis, the paradigm changed. The average cruise speed on newly developed aircraft started to decrease in exchange for improvements in many other performance parameters. At the same pace, the airliner’s powerplants are evolving to look more like a ducted turboprop, and less like a pure jet engine as the pursuit for the higher bypass ratios continues. However, since the birth of jet aircraft, the propeller-driven plane lost its dominant place in the market. Associated with the idea of going back to propeller-driven airplanes, and what it represented in terms of modernity and security, it started a propeller avoidance phenomenon on the travelers and thus on the airlines. Today, even with the modest research effort since the 1980s, the advanced propellers are getting closer efficiencies to the jet-powered engines at their contemporary typical cruise speeds. This paper gives a brief overview of the performance trends in aviation since the last century. Comparison examples between aircraft designed on different paradigms are presented. The use of propellers as a reborn propulsive device is discussed.
 Keywords: Propeller, Aircraft, Turboprop, Flight efficiency, Flight speed

Mixed Reality Simulation of High-Endurance Unmanned Aerial Vehicle with Dual-Head Electromagnetic Propulsion Devices for Earth and Other Planetary Explorations

One of the major limitations of existing unmanned aerial vehicles is limited flight endurance. In this study, we designed an innovative uninterrupted electromagnetic propulsion device for high-endurance missions of a quadcopter drone for the lucrative exploration of earth and other planets with atmospheres. As an airborne platform, this device could achieve scientific objectives better than state-of-the-art revolving spacecraft and walking robots, without any terrain limitation. We developed a mixed reality simulation based on a quadcopter drone and an X-Plane flight simulator. A computer with the X-Plane flight simulator represented the virtual part, and a real quadcopter operating within an airfield represented the real part. In the first phase of our study, we developed a connection interface between the X-Plane flight simulator and the quadcopter ground control station in MATLAB. The experimental results generated from the Earth’s atmosphere show that the flight data from the real and the virtual quadcopters are precise and very close to the prescribed target. The proof-of-concept of the mixed reality simulation of the quadcopter at the Earth atmosphere was verified and validated through several experimental flights of the F450 spider quadcopter with a Pixhawk flight controller with the restricted endurance at the airfield location of Hangang Drone Park in Seoul, South Korea. We concluded that the new generation drones integrated with lightweight electromagnetic propulsion devices are a viable option for achieving unrestricted flight endurance with improved payload capability for Earth and other planetary explorations with the aid of mixed reality simulation to meet the mission flight path demands. This study provides insight into mixed reality simulation aiming for Mars explorations and high-endurance missions in the Earth’s atmosphere with credibility using quadcopter drones regulated by dual-head electromagnetic propulsion devices.