scholarly journals Study of plasma dynamics in the HET relying on global thruster characteristics parameterized with discharge voltage

2021 ◽  
Vol 136 (7) ◽  
Author(s):  
A. Szelecka ◽  
M. Jakubczak ◽  
A. Riazantsev ◽  
J. Kurzyna
Keyword(s):  
Discharge Current ◽  
Specific Impulse ◽  
Diagnostic System ◽  
Discharge Voltage ◽  
Operating Conditions ◽  
Ion Current ◽  
Plasma Dynamics ◽  
Engine Operation ◽  
Current Collection ◽  
Hall Effect Thruster

AbstractA prototype of krypton Hall-effect thruster (HET) of 0.5 kW nominal power and a dedicated diagnostic system for ion current collection were designed in the laboratory of plasma space propulsion (PlaNS) of the Institute of Plasma Physics and Laser Microfusion (IPPLM) in Warsaw. The diagnostic system consisting of a collimated Faraday Cup (FC) and a Planar Probe with Guarding Ring, named also Faraday Probe (FP) was intended to capture both temporal and spatial ion current variation, allowing to analyze not only ion current dynamics locally but also to estimate the total ion current value and a plasma jet divergence. Reliable engine operation provided by stability of plasma in a discharge channel of the thruster is unambiguously reflected in the oscillations of the discharge current. The so-called breathing mode, categorized as ionization instability with frequencies in the range of 10–30 kHz, is commonly recognized in the HET’s discharge current. Rising of instabilities makes it difficult to increase the specific impulse effectively by just simply attempting to operate thruster in high-voltage regime because it may result in very irregular thruster functioning and often to ceasing of plasma. Discharge current oscillations should also be strongly reflected in the ion current. Indeed, a similar to discharge current behavior was observed in the recorded FC and FP ion current signals. By changing thruster operating conditions, like discharge voltage and magnitude of B-field, transitions between smooth and oscillating current regimes were examined. Studying the ion current dynamics seems particularly important, since it is predicted that the control of discharge instabilities may be crucial to improve the performance of HETs in the future.

Fabrication and Testing of Applied-Field Magneto Plasma Dynamic Thruster with Argon Propellant

2021 ◽  
Vol 13 (3) ◽  
Author(s):  
C. Akash ◽  
M. Mahavishnc ◽  
E. Manikandan ◽  
M. Manikandan ◽  
K. Vijayaraja
Keyword(s):  
Permanent Magnet ◽  
Discharge Current ◽  
Applied Field ◽  
Specific Impulse ◽  
Space Mission ◽  
Operating Conditions ◽  
Low Thrust ◽  
Plasma Dynamic ◽  
Power Circuit ◽  
High Discharge

The experimental setup of applied-field Magneto Plasma Dynamic Thruster (MPDT) is a form of electrically powered spacecraft propulsion system. The thrusters are used for deep space mission, which consist of long duration, low thrust acceleration and less propellant storage. MPDT uses the force on the charged particle by an electromagnetic field to generate thrust. The technology takes high discharge current for two electrodes and solenoid coil as applied-field. In the present investigation, the high discharge current is replaced by a limited discharge current, it is reduced by the use of capacitors bank to discharge the current for two electrodes. The solenoid coils are replaced by permanent magnet as applied-field to generate the thrust. The basic requirements for MPDT are the power circuit made by capacitors bank of electrolytic type. The electrolytic capacitors are smaller in size and produces limited voltage, which will support limited current flowing between the two electrodes. The material used for anode and cathode are copper and tungsten respectively. A permanent magnet is fixed over the anode coaxially and cathode is placed in center. A propellant will be injected in between the two electrodes. The propellant gas used in this thruster is argon. The performance of the thruster is tested in vacuum condition and the thrust value is measured by a load cell. The prototype of MPDT is tested and measurement of discharge current, thrust, specific impulse and efficiency are carried out. The thrust for various discharge current is measured and the efficient operating conditions of MPDT can be obtained.

scholarly journals Plume Divergence and Discharge Oscillations of an Accessible Low-Power Hall Effect Thruster

2021 ◽  
Vol 11 (4) ◽  
pp. 1973
Author(s):  
Matthew Baird ◽  
Thomas Kerber ◽  
Ron McGee-Sinclair ◽  
Kristina Lemmer
Keyword(s):  
Hall Effect ◽  
Discharge Current ◽  
Electric Propulsion ◽  
Low Voltage ◽  
Discharge Voltage ◽  
Operating Conditions ◽  
Low Flow ◽  
Divergence Angle ◽  
Frequency Spectra ◽  
Plume Divergence

Hall effect thrusters (HETs) are an increasingly utilized proportion of electric propulsion devices due to their high thrust-to-power ratio. To enable an accessible research thruster, our team used inexpensive materials and simplified structures to fabricate the 44-mm-diameter Western Hall Thruster (WHT44). Anode flow, discharge voltage, magnet current, and cathode flow fraction (CFF) were independently swept while keeping all other parameters constant. Simultaneously, a Faraday probe was used to test plume properties at a variety of polar coordinate distances, and an oscilloscope was used to capture discharge oscillation behavior. Plasma plume divergence angle at a fixed probe distance of 4.5 thruster diameters increased with increasing anode flow, varying from 36.7° to 37.4°. Moreover, divergence angle decreased with increasing discharge voltage, magnet current, and CFF, by 0.3°, 0.2°, and 8°, respectively, over the span of the swept parameters. Generally, the thruster exhibited a strong oscillation near 90 kHz, which is higher than a similarly sized HET (20–60 kHz). The WHT44 noise frequency spectra became more broadband and the amplitude increased at a CFF of less than 1.5% and greater than 26%. Only the low flow and low voltage operating conditions showed a quiescent sinusoidal discharge current; otherwise, the discharge current probability distribution was Gaussian. This work demonstrates that the WHT44 thruster, designed for simplicity of fabrication, is a viable tool for research and academic purposes.

scholarly journals Performance tests of IPPLM's krypton Hall thruster

2018 ◽  
Vol 36 (1) ◽  
pp. 105-114 ◽  
Author(s):  
Jacek Kurzyna ◽  
Maciej Jakubczak ◽  
Agnieszka Szelecka ◽  
Käthe Dannenmayer
Keyword(s):  
Electric Propulsion ◽  
Specific Impulse ◽  
Operating Conditions ◽  
Hall Thruster ◽  
Laboratory Model ◽  
Attractive Alternative ◽  
Stable Operation ◽  
Performance Tests ◽  
Hall Effect Thruster ◽  
Wide Range

AbstractThe Institute of Plasma Physics and Laser Microfusion's (IPPLM) Hall effect thruster (Krypton Large IMpulse Thruster, KLIMT) is a 500 W class plasma engine with a mean diameter of discharge channel of 42 mm. KLIMT was developed within ESA/PECS project aiming to provide relatively small thruster for satellites that would be able to effectively operate with krypton propellant. Being several times less expensive than xenon, which is regarded as a propellant of choice for electric propulsion of electrostatic type, krypton since years has been suggested as an attractive alternative. In this paper, a design as well as performance tests of the laboratory model of KLIMT are discussed. It is shown that precise adjustment of magnetic field topography results in the stable operation of the thruster in wide range of operating conditions providing similar thrust and specific impulse production for both propellants. Maximum thrust produced with the use of xenon and krypton reached about 16–17 mN for mass flow rate of 1.15–1.2 mg/s resulting in specific impulse in the range of 1300–1500 s (13–15 km/s). However, for krypton the anode efficiency drops by ~10% in comparison with xenon. For krypton plasma beam divergence as measured by an average half-angle with respect to the beam axis was found to remain within the range of 19–23° for the whole set of the examined operating conditions. The reported characteristics are reasonable for Hall thruster of the discussed size and power.

Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

2018 ◽  
Vol 77 (4) ◽  
pp. 222-229 ◽  
Author(s):  
A. V. Paranin ◽  
A. B. Batrashov
Keyword(s):  
Mathematical Model ◽  
Operating Conditions ◽  
Scale Model ◽  
Contact Network ◽  
Scaled Model ◽  
Cross Sectional ◽  
Current Collection ◽  
Topological Features ◽  
Study Results ◽  
Real Physical Process

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

scholarly journals A New Method to Determine the Impact of Individual Field Quantities on Cycle-to-Cycle Variations in a Spark-Ignited Gas Engine

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4136
Author(s):  
Clemens Gößnitzer ◽  
Shawn Givler
Keyword(s):  
Kinetic Energy ◽  
Flow Field ◽  
Turbulent Kinetic Energy ◽  
Negative Impact ◽  
Operating Conditions ◽  
Engine Operation ◽  
Gas Engine ◽  
Cycle Simulation ◽  
Simulation Results ◽  
The Impact

Cycle-to-cycle variations (CCV) in spark-ignited (SI) engines impose performance limitations and in the extreme limit can lead to very strong, potentially damaging cycles. Thus, CCV force sub-optimal engine operating conditions. A deeper understanding of CCV is key to enabling control strategies, improving engine design and reducing the negative impact of CCV on engine operation. This paper presents a new simulation strategy which allows investigation of the impact of individual physical quantities (e.g., flow field or turbulence quantities) on CCV separately. As a first step, multi-cycle unsteady Reynolds-averaged Navier–Stokes (uRANS) computational fluid dynamics (CFD) simulations of a spark-ignited natural gas engine are performed. For each cycle, simulation results just prior to each spark timing are taken. Next, simulation results from different cycles are combined: one quantity, e.g., the flow field, is extracted from a snapshot of one given cycle, and all other quantities are taken from a snapshot from a different cycle. Such a combination yields a new snapshot. With the combined snapshot, the simulation is continued until the end of combustion. The results obtained with combined snapshots show that the velocity field seems to have the highest impact on CCV. Turbulence intensity, quantified by the turbulent kinetic energy and turbulent kinetic energy dissipation rate, has a similar value for all snapshots. Thus, their impact on CCV is small compared to the flow field. This novel methodology is very flexible and allows investigation of the sources of CCV which have been difficult to investigate in the past.

Experimental Investigation of a Heavy-Duty Compression-Ignition Engine Retrofitted to Natural Gas Spark-Ignition Operation

2019 ◽  
Vol 141 (11) ◽  
Author(s):  
Jinlong Liu ◽  
Hemanth Kumar Bommisetty ◽  
Cosmin Emil Dumitrescu
Keyword(s):  
Natural Gas ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Compression Ignition ◽  
Heavy Duty ◽  
Compression Ignition Engine ◽  
Engine Operation ◽  
Cycle Variation ◽  
Spark Timing ◽  
Ci Engines

Heavy-duty compression-ignition (CI) engines converted to natural gas (NG) operation can reduce the dependence on petroleum-based fuels and curtail greenhouse gas emissions. Such an engine was converted to premixed NG spark-ignition (SI) operation through the addition of a gas injector in the intake manifold and of a spark plug in place of the diesel injector. Engine performance and combustion characteristics were investigated at several lean-burn operating conditions that changed fuel composition, spark timing, equivalence ratio, and engine speed. While the engine operation was stable, the reentrant bowl-in-piston (a characteristic of a CI engine) influenced the combustion event such as producing a significant late combustion, particularly for advanced spark timing. This was due to an important fraction of the fuel burning late in the squish region, which affected the end of combustion, the combustion duration, and the cycle-to-cycle variation. However, the lower cycle-to-cycle variation, stable combustion event, and the lack of knocking suggest a successful conversion of conventional diesel engines to NG SI operation using the approach described here.

Experimental and Analytical Characterization of Alternative Aviation Fuel Sprays Under Realistic Operating Conditions

2018 ◽  
Author(s):  
Andrew Corber ◽  
Nader Rizk ◽  
Wajid Ali Chishty
Keyword(s):  
Experimental Data ◽  
Alternative Fuels ◽  
Laser Sheet ◽  
National Research Council ◽  
Diagnostic System ◽  
Operating Conditions ◽  
Aviation Fuel ◽  
Injection System ◽  
Test Time

The National Jet Fuel Combustion Program (NJFCP) is an initiative, currently being led by the Office of Environment & Energy at the FAA, to streamline the ASTM jet fuels certification process for alternative aviation fuels. In order to accomplish this objective, the program has identified specific applied research tasks in several areas. The National Research Council of Canada (NRC) is contributing to the NJFCP in the areas of sprays and atomization and high altitude engine performance. This paper describes work pertaining to atomization tests using a reference injection system. The work involves characterization of the injection nozzle, comparison of sprays and atomization quality of various conventional and alternative fuels, as well as use of the experimental data to validate spray correlations. The paper also briefly explores the application viability of a new spray diagnostic system that has potential to reduce test time in characterizing sprays. Measurements were made from ambient up to 10 bar pressures in NRC’s High Pressure Spray Facility using optical diagnostics including laser diffraction, phase Doppler anemometry (PDA), LIF/Mie Imaging and laser sheet imaging to assess differences in the atomization characteristics of the test fuels. A total of nine test fluids including six NJFCP fuels and three calibration fluids were used. The experimental data was then used to validate semi-empirical models, developed through years of experience by engine OEMs and modified under NJFCP, for predicting droplet size and distribution. The work offers effective tools for developing advanced fuel injectors, and generating data that can be used to significantly enhance multi-dimensional combustor simulation capabilities.

scholarly journals Study of the possibility of obtaining nanocrystalline cellulose in a single stage plasma chemical process

2021 ◽  
pp. 17-23
Keyword(s):  
Microcrystalline Cellulose ◽  
Direct Current ◽  
Discharge Current ◽  
Atmospheric Pressure ◽  
Chemical Process ◽  
Discharge Voltage ◽  
Nanocrystalline Cellulose ◽  
Plasma Chemical ◽  
Small Surface ◽  
Direct Current Discharge

The paper considers the possibility of obtaining nanocrystalline cellulose (NCC) by gas-discharge treatment of aqueous suspensions of microcrystalline cellulose or filter paper. For processing, a direct current discharge was used at atmospheric pressure with a wa-ter cathode at a discharge current of 35 mA and a discharge voltage of 1500 V. It was found that the plasma-chemical treatment of cellulose-containing material in water without the use of other reagents leads to the release of NCC with relatively large parti-cle sizes and a small surface charge.

Design and Testing of a Lab-Scale Hybrid Rocket Motor to Evaluate Swirl Injection Characteristics

2018 ◽  
pp. 185-210
Author(s):  
Susane R. Gomes ◽  
Leopoldo J. Rocco
Keyword(s):  
Swirling Flow ◽  
Specific Impulse ◽  
Operating Conditions ◽  
Geometrical Parameters ◽  
Operating Pressure ◽  
Hybrid Rocket ◽  
Rocket Motors ◽  
Mathematical Background ◽  
Design And Testing ◽  
Firing Tests

This research aims to provide a methodology for the project of labscale hybrid motors. This development began with the thermal analysis of the fuel grain using the Flynn, Wall and Ozawa method, generating simulation entry data to maximize the motor performance. The simulation was performed with the Chemical Equilibrium Specific Impulse Code. Based on the optimum oxidizer to fuel ratio, the literature was used to supply the mathematical background to calculate the motor geometrical parameters whose operating conditions were determined throughout the simulation. Finally, firing tests were conducted to verify the reliability of the project methodology. The firing tests were performed with three injectors: two swirling and one axial. The tests showed that the higher the operating pressure the more suitable is the project, meaning the methodology developed works best in hybrid rocket motors with high operating pressures. Additionally, it was shown that the swirling flow injectors produce higher efficiency.

scholarly journals Comparison of numerical predictions of the supersonic expansion inside micronozzles of micro–resistojets

2019 ◽  
Vol 304 ◽  
pp. 02012
Author(s):  
Maria Grazia De Giorgi ◽  
Donato Fontanarosa ◽  
Antonio Ficarella
Keyword(s):  
Specific Impulse ◽  
Direct Simulation Monte Carlo ◽  
Operating Conditions ◽  
Rapid Expansion ◽  
Partial Slip ◽  
Navier Stokes ◽  
Numerical Predictions ◽  
Simulation Monte Carlo ◽  
Nitrogen Flows ◽  
Numerical Approaches

The present work provides a numerical investigation of the supersonic flow inside a planar micronozzle configuration under different gas rarefaction conditions. Two different propellants have been considered, namely water vapor and nitrogen, which relate to their use in VLMs (the former) and cold gas microthrusters (the latter), respectively. Furthermore, two different numerical approaches have been used due to the different gas rarefaction regime, i.e. the typical continuum Navier–Stokes with partial slip assumption at walls and the particle–based Direct Simulation Monte Carlo (DSMC) technique. As a result, under high–pressure operating conditions, both water and nitrogen flows supersonically expanded into the micronozzle without chocking in combination with a linear growth of the boundary layer on walls. However, when low–pressure operating condition are imposed and a molecular regime is established inside the micronozzle, a very rapid expansion occurred close to the nozzle exit in combination with a strong chocking of the flow and a micronozzle quality reduction of about 40%. Furthermore, water exhibited specific higher specific impulse than nitrogen above 60%.

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