Performance Simulation of a 5 kW hall Thruster

Hall thruster is a kind of plasma optics device, which is used mainly in space propulsion. To simulate the discharge process of plasma and the performance of a 5 kW hall thruster, a two-dimensional PIC-MCC model in the R-Z plane is built. In the model, the anomalous diffusion of the electrons including Bohm diffusion and near-wall conduction is modeled. The Bohm diffusion is modeled by using a Brownian motion instead of the Bohm collision method and the near-wall conduction is modeled by a secondary electron emission model. In addition to the elastic, excitation, and ionization collisions between electrons and neutral atoms, the Coulomb collisions are included. The plasma discharge process including the transient oscillation and steady state oscillation is well reproduced. First, the influence of the discharge voltage and magnetic field on the steady state oscillation is simulated. The oscillation amplitude increases as the discharge voltage gets larger at first, and then decreases. While the oscillation amplitude decreases as the magnetic field gets stronger at first, and then increases. Later, the influence of the discharge voltage and mass flow rate on the performance of the thruster is simulated. When the mass flow rate is constant, the total efficiency initially increases with the discharge voltage, reaches the maximum at 600 V, and then declined. When the discharge voltage is constant, the total efficiency increases as the mass flow rate rises from 10 to 15 mg/s. Finally, a comparison between simulated and experimental performance reveals that the largest deviation is within 15%, thereby indirectly validating the accuracy of the model.

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Modelling of a Single Passage Air PV/T Solar Collector: Experimental and Simulation Design

Processes ◽

10.3390/pr8070763 ◽

2020 ◽

Vol 8 (7) ◽

pp. 763

Author(s):

Noran Nur Wahida Khalili ◽

Mahmod Othman ◽

Mohd Nazari Abu Bakar ◽

Lazim Abdullah

Keyword(s):

Error Analysis ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Solar Collector ◽

Total Efficiency ◽

Research Attention ◽

Air Mass ◽

One Dimensional ◽

Simulation Results

The hybrid photovoltaic/thermal solar collector has attracted research attention for more than five decades. Its capability to produce thermal energy simultaneously with electrical energy is considered attractive since it provides higher total efficiency than stand-alone photovoltaic or thermal systems separately. This paper describes theoretical and experimental studies of a finned single pass air-type photovoltaic/thermal (PV/T) solar collector. The performance of the system is calculated based on one dimensional (1D) steady-state analysis using one dimensional energy balance equations, where simulation was carried out using MATLAB. Experiments were carried out to observe the performance of the solar collector under changes in air mass flow rate. Experimental values on photovoltaic panel temperature and air temperature on both air inlet and outlet, together with the ambient temperature and solar radiation were measured. The simulation results were validated against the results obtained from experiments using the error analysis method, Root Mean Square Error. At a solar irradiance level of 800 to 900 W/m2, the thermal efficiency increases to 20.32% while the electrical efficiency increases to 12.01% when the air mass flow rate increases from 0.00015 kg/s to 0.01 kg/s. The error analysis shows that both experimental and simulation results are in good agreement.

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Effects of the magnetic field direction and of the cross-sectional aspect ratio on the mass flow rate of MHD duct flows

Fusion Engineering and Design ◽

10.1016/j.fusengdes.2019.111373 ◽

2020 ◽

Vol 151 ◽

pp. 111373

Author(s):

Xuejiao Xiao ◽

Chang Nyung Kim

Keyword(s):

Magnetic Field ◽

Aspect Ratio ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Field Direction ◽

Magnetic Field Direction ◽

Cross Sectional ◽

The Cross ◽

The Magnetic Field

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Modified Electromechanical Modeling and Parameters Analysis of Magnetoplasmadynamic Thruster

Energies ◽

10.3390/en12122428 ◽

2019 ◽

Vol 12 (12) ◽

pp. 2428

Author(s):

Yu Zhang ◽

Jianjun Wu ◽

Yang Ou ◽

Jian Li ◽

Sheng Tan

Keyword(s):

Magnetic Field ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Applied Magnetic Field ◽

Electromechanical Model ◽

Electromechanical Modeling ◽

Low Mass ◽

Thrust Performance ◽

Good Agreement

To predict the thrust of magnetoplasmadynamic thrusters (MPDTs), a modified electromechanical model was proposed and a comparison with experimental results is presented in this paper. The motion of propellant in the thruster was divided into two portions: the axial motion which was accelerated by the interaction of current and induced self-field, and the swirling motion which was accelerated by the interaction of current and applied magnetic field. The electromechanical model was in good agreement with the experimental data, and the fitting degrees of the model were greater than 0.93. Furthermore, the influence of parameters on the performance of MPDT were investigated by utilizing the electromechanical model. The results indicate that the thrust performance of the thruster improved with the increase of discharge current, anode radius, applied magnetic field strength, and the decrease of mass flow rate. However, the large anode radius and low mass flow rate readily led to the failure of thruster function. Therefore, the model can not only predict the thrust performance of MPDTs, but also guide the design and operation optimization of the thruster.

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The Effects of Non-uniform Distribution of Oxidizer Flow on High-Frequency Combustion Instability

MATEC Web of Conferences ◽

10.1051/matecconf/201925701005 ◽

2019 ◽

Vol 257 ◽

pp. 01005

Author(s):

Peng Chen ◽

Wansheng Nie ◽

Kangkang Guo ◽

Xing Sun ◽

Yu Liu ◽

...

Keyword(s):

Heat Release ◽

Combustion Chamber ◽

Uniform Distribution ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Rocket Engine ◽

Combustion Instability ◽

Oscillation Amplitude ◽

Pressure Oscillation

The numerical calculation of three-dimensional unsteady combustion for the combustion chamber of LOX/kerosene high pressure staged combustion rocket engine was carried out. By changing the offset ratio of oxygen mass flow rate in the edge area of the injector face, computational studies were conducted to investigate the effects of non-uniform distribution of oxidizer flow on combustion instability for a liquid-propellant rocket engine. The calculation results show that the offset ratio of oxygen mass flow rate changes the distribution of heat release in the combustion chamber. Within a certain range of offset ratio, the non-uniform distribution degree of oxidizer flow enhances the coupling between the pressure and heat release. As a result, it leads to an increase in the pressure oscillation amplitude in the combustion chamber. However, if the offset ratio is too large, the oxygen-fuel ratio will be too small in some regions, which will reduce coupling between the pressure and heat release and increase the damping of combustion instability.

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Effect of the honeycomb tip with injection on the aerodynamic performance in a 1.5-stage turbine

Journal of Turbomachinery ◽

10.1115/1.4048698 ◽

2020 ◽

pp. 1-25

Author(s):

Jianyang Yu ◽

Yabo Wang ◽

YanPing Song ◽

Fu Chen

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Pressure Loss ◽

Total Pressure ◽

Total Pressure Loss ◽

Navier Stokes ◽

Total Efficiency ◽

Cavity Depth ◽

Tip Leakage

Abstract Three kinds of rotor tip configurations have been investigated numerically in the LISA 1.5-stage turbine, including the flat tip, the honeycomb tip and the honeycomb tip with injection. The effect of the cavity depth and the injection mass flow rate on the turbine performance is studied in detail, evaluated by the isentropic total-to-total efficiency and the tip leakage mass flow rate. The Reynolds-averaged Navier-Stokes (RANS) method and the k-ω turbulence model are adopted in all the present computations. The numerical results show that the first stage efficiency is increased by up to 0.66% and the tip leakage mass flow rate is reduced by about 1.87% of the main flow. The pressure field and the flow feature inside the gap are explored. The flow structures and the total pressure loss contours in the rotor passage are presented. Finally, the total pressure loss is newly defined by considering the injection effect. It is indicated that the injection mass flow rate should be carefully determined for excellent overall performance.

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Numerical and Experimental Studies of Gas Pulsations in the Suction Manifold of a Multicylinder Automotive Compressor

Journal of Vibration and Acoustics ◽

10.1115/1.2732352 ◽

2008 ◽

Vol 130 (1) ◽

Cited By ~ 3

Author(s):

Jeong-Il Park ◽

Nasir Bilal ◽

Douglas E. Adams ◽

Yoshinobu Ichikawa ◽

Jacob Bayyouk

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Experimental Studies ◽

Beam Equation ◽

Discharge Process ◽

Simulation Code ◽

Calculated Mass ◽

Linear Differential ◽

Gas Pulsations

This study predicts gas pulsations in the suction manifold of a multicylinder automotive air-conditioning compressor using a comprehensive simulation model of a reciprocating compressor. On the basis of the first law of thermodynamics and a simplified fourth-order Bernoulli-Euler linear differential beam equation for suction valves, the pressure in a cylinder and resultant pressure pulsation in the suction manifold are predicted. The mass flow rate through the valve is estimated assuming one-dimensional compressible flow through an orifice. All of the equations are then solved together in a sequence to obtain the pressure in the cylinder, valve response, and the mass flow rate. A complicated suction manifold geometry is modeled as a simplified cylindrical annular cavity to study gas pulsations in a multicylinder compressor, but the discharge process has not been considered in this study. Using the calculated mass flow rate, pressure pulsations in a simplified cylindrical annular cavity with an area change to consider “mode splitting” are predicted based on the characteristic cylinder method. It is shown that the simulation code can be a useful tool for predicting gas pulsations in the suction manifold of a multicylinder automotive compressor.

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Study of the Greitzer Model for Centrifugal Compressors: Variable Lc Parameter and Two Types of Surge

Energies ◽

10.3390/en13226072 ◽

2020 ◽

Vol 13 (22) ◽

pp. 6072

Author(s):

Filip Grapow ◽

Grzegorz Liśkiewicz

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Linear Trend ◽

Oscillation Amplitude ◽

Pressure Oscillation ◽

Tuning Parameter ◽

Model Parameters ◽

Model Compressor ◽

Best Fit

In this paper, the Greitzer surge model was systematically analysed with the model compressor duct length Lc as the tuning parameter. The surge phenomenon is known to induce a serious risk to centrifugal compressor operation. The two-dimensional Greitzer model is a well-established way of modelling this dangerous instability, but the determination and changes of the model parameters are still being discussed. In this paper an automated procedure determines the Lc value providing the best fit with the experimental data has been presented. The algorithm was tested on five valve positions and revealed that the best fit was obtained for different Lc values following a linear trend against the mass flow rate. The study has also shown that the Greitzer model has two solutions for a given pressure oscillation amplitude: one similar to the deep surge (low Lc) and one similar to the mild surge (low Lc). This suggests that this model can be used to simulate both types of the phenomenon known from the experimental analyses. The study proposes the dimensionless average pressure as the parameter allowing to distinguish which surge cycle was observed at a given instance. Past papers were analysed to observe the surge type that appeared in different experiments. It was found that most researchers obtained low Lc surge. The results show that both deep and mild surge could be simulated with the Greitzer model. It also revealed that the Lc should not be treated as a constant value for a given machine and that it changes with the mass flow rate.

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Low power thrust measurements of the water electrolysis Hall effect thruster

CEAS Space Journal ◽

10.1007/s12567-021-00350-y ◽

2021 ◽

Author(s):

Alexander Schwertheim ◽

Aaron Knoll

Keyword(s):

Magnetic Field ◽

Hall Effect ◽

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Specific Impulse ◽

Covalent Bond ◽

Water Electrolysis ◽

Hall Effect Thruster ◽

Thrust Efficiency

AbstractWe propose that a Hall effect thruster could be modified to operate on the products of water electrolysis. Such a thruster would exploit the low cost and high storability of water while producing gaseous hydrogen and oxygen in-situ as they are required. By supplying the anode with oxygen and the cathode with hydrogen, the poisoning of the cathode is mitigated. The water electrolysis Hall effect thruster (WET-HET) has been designed to demonstrate this concept. The dimensions of the WET-HET have been optimized for oxygen operation using PlasmaSim, a zero-dimensional particle in cell code. We present the first direct thrust measurements of the WET-HET. A hanging pendulum style thrust balance is used to measure the thrust of the WET-HET while operating in the Boltzmann vacuum facility within the Imperial Plasma Propulsion Laboratory. For this test the beam was neutralized using a filament plasma bridge neutralizer operating on krypton. We find thrust, specific impulse, and thrust efficiency all increase linearly with power for values between 400 and 1050 W. Increasing the mass flow rate from 0.96 to 1.85 mg/s increases thrust at the expense of specific impulse. Changing mass flow rate was found to have little impact on the thrust efficiency over this range. An optimal radial magnetic flux density of 403 G at the exit plane is found. Further increases to the magnetic field beyond this point were found to decrease the thrust, specific impulse and thrust efficiency, whereas the discharge voltage increased monotonically with increasing magnetic field for a given input power. It was found that the experimental thruster performance was lower than the simulation results from PlasmaSim. However, the general trends in performance as a function of power and propellant mass flow rate were preserved. We attribute a portion of this discrepancy to the inability of the simulation to model the energy absorbed by the covalent bond of the oxygen molecule. For the powers and mass flow rates surveyed we measured thrust ranging from 4.52$$\pm 0.18\,$$ ± 0.18 to 8.45$$\pm 0.18\,$$ ± 0.18 mN, specific impulse between 324$$\pm 12\,$$ ± 12 and 593$$\pm 12\,$$ ± 12 s, and anode thrust efficiencies between 1.34$$\pm 0.10\,$$ ± 0.10 and 2.34$$\pm 0.10\,$$ ± 0.10 %.

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