Search

The energy supply mode of a micro-cathodic arc thruster (μ-CAT) was adjusted based on the charge and discharge characteristics of the energy storage element, and the cathode discharge characteristics of μ-CAT were studied under different energy supply modes. We applied an electrical method to measure the discharge characteristics of μ-CAT, with an enhanced intensified charge coupled device spectrum detector to measure the plasma parameters of μ-CAT, allowing analysis of the internal logic among thruster plasma parameters, arc discharge characteristics, and thruster energy supply mode. The mechanisms of μ-CAT were analyzed and characteristics of accumulated discharge, energy distribution, and ion velocity distribution of thruster were compared under different energy supply modes to obtain the effect of the energy supply mode on the discharge characteristics of the interelectrode of μ-CAT. The results show that the energy supply mode of μ-CAT affected the ionization characteristics and ionization stability of the micro-cathodic arc thruster, causing a multistage ionization difference in the cathode metal target. This would not only affect the propulsion performance of the thruster, but also affect the change of the number of particles in the cathode region in a single discharge cycle. [ABSTRACT FROM AUTHOR]

Purpose: The geometric parameters of the compressor blade have a noteworthy influence on compressor stability, which should be meticulously designed. However, machining inaccuracies cause the blade geometric parameters to deviate from the ideal design, and the geometric deviation exhibits high randomness. Therefore, the purpose of this study is to quantify the uncertainty and analyze the sensitivity of the impact of blade geometric deviation on compressor stability. Design/methodology/approach: In this work, the influence of blade geometric deviation is analyzed based on a subsonic compressor rotor stage, and three-dimensional numerical simulations are used to compute samples with different geometric features. A method of combining Halton sequence and non-intrusive polynomial chaos is adopted to carry out uncertainty quantitative analysis. Sobol' index and Spearman correlation coefficient are used to analysis the sensitivity and correlation between compressor stability and blade geometric deviation, respectively. Findings: The results show that the compressor stability is most sensitive to the tip clearance deviation, whereas deviations in the leading edge radius, trailing edge radius and chord length have minimal impact on the compressor stability. And, the effects of various blade geometric deviations on the compressor stability are basically independent and linearly superimposed. Originality/value: This work provided a new approach for uncertainty quantification in compressor stability analysis. The conclusions obtained in this work provide some reference value for the manufacturing and maintenance of rotor blades. [ABSTRACT FROM AUTHOR]

The blade thickness distribution is an important geometric parameter of a compressor rotor blade. It determines the aerodynamic performance of a rotor, which should be carefully designed. However, the manufacturing inaccuracies cause the blade thickness distribution to deviate from the ideal design. These geometric deviations alter the flow field near the blade surface, which affects the aerodynamic performance of the rotor. Therefore, it is of great significance to quantitatively investigate the effects of blade thickness deviation on the aerodynamic performance. In this paper, the influence of blade thickness deviation on the flow field is analyzed based on a transonic compressor rotor, and an uncertainty quantification process is performed to study the effects of blade thickness deviation on the aerodynamic performance. Cases with different geometry features are checked in the current study using 3-dimensional Reynolds-averaged Navier–Stokes simulations. Results show that the blade thickness deviation leads to changes in the intensities of the expansion wave in the upper part of the blade suction and the passage shock wave, which affects the supercharging process of the rotor. The influence of thickness deviation on the strength of the tip leakage vortex changes the isentropic efficiency of the rotor. The results of the uncertainty quantitative analysis indicate that the linear correlation between the variation of rotor performance and the thickness deviation is strong when the machining accuracy is high, whereas the linear correlation between the two is weakened when the tolerance range is larger. [ABSTRACT FROM AUTHOR]

In this paper, the relationship between the morphology of the cathode crater and plasma ionization between thrusters is studied by adjusting the input energy of the micro-cathode arc thruster (μ CAT). We monitor the morphology of the cathode crater of the μ CAT using scanning electron microscopy and explore the relationship between the crater morphology and the internal energy loss of the cathode crater. This relationship, combined with the numerical simulation results, is used to monitor the ionization between the electrodes of the μ CAT using an enhanced intensified charge coupled device spectrum detector. The effect of cathode crater morphology on the ionization of the propellant during the operation of the μ CAT is determined. The results show that with a change in the input power processing unit voltage, the external profile and depth-to-diameter ratio of the cathode crater change, resulting in a change in the internal energy loss of the thruster cathode crater and then affecting the ionization efficiency of the cathode working fluid in the μ CAT. Under the condition of basically unchanged cathode feed energy flow density, reasonable adjustment of the depth-to-diameter ratio of the cathode crater can effectively improve the ionization efficiency of the cathode working fluid in the μ CAT. [ABSTRACT FROM AUTHOR]

The impact of geometric deviation due to manufacturing on compressor performance is considerable in engineering practice. To investigate the impact of blade thickness deviation on compressor performance and flow loss at various rotational speeds, a three-dimensional steady numerical simulation on Rotor 37 was conducted. The quantification of uncertainty was accomplished using a non-intrusive polynomial chaos method. The viscous dissipation coefficient was introduced to analyze the uncertain influence of blade thickness deviation on flow loss. Based on the type of loss source, the flow field was divided into six regions, including the blade tip region, blade root region, leading edge region, trailing edge region, blade surface region, and mainstream region. The results indicate that the sensitivity of total pressure ratio to thickness deviation increases significantly with an increase in the rotational speed. Under peak efficiency conditions, the effect of blade thickness deviation on flow dissipation in leading edge region decreases initially and then increases with an increase in the rotational speed. Meanwhile, the impact on flow loss in other regions increases with the increase in the rotational speed. Under near stall conditions, the blade thickness deviation has a great impact on the flow losses in the blade tip region, leading edge region, and mainstream region at 60% design rotational speed. However, the blade tip region and trailing edge region are more noticeably affected at 100% design rotational speed. Furthermore, the quantification of standard deviation of flow losses in various regions under different rotational speeds and conditions reveals that the flow loss fluctuation in the leading edge region and mainstream region varies with changes in operating conditions and rotational speeds, but the fluctuation of flow loss in other regions is independent of the rotational speed. [ABSTRACT FROM AUTHOR]

This study proposes a newly designed ignition circuit that does not change the ignition starting parameters of a Hall thruster, reduces the critical ignition voltage, and improves ignition reliability. The complexity and weight of the Hall thruster power supply system are reduced by multiplexing the ignition and discharge power supplies. Under the condition that the design parameters are satisfied, that is, R 3 + R E C 2 is much larger than RCC1, the residual energy in the circuit after the cathode breakdown can be fed into the thruster discharge channel to improve the ignition energy supply. The experimental results show that when the anode voltage is 98 V, only nine of the 100 ignition tests are successful using the traditional ignition circuit, whereas the number of successes using the newly designed ignition circuit is as high as 99, which provides a simple solution method for improving the ignition reliability. [ABSTRACT FROM AUTHOR]

Micro-cathode arc thrusters have been widely used in micro-nanosatellites owing to their high specific impact, long lifetime, repeatable startup, low thrust and high control precision. Micro-cathode arc thrusters and their derivatives are currently being developed and optimized. The micro-cathode arc thruster can generate plasma stably and efficiently, and form a thrust force under a magnetic field with very low power in pulsed operation mode. This paper reviews the last 20 years of literature on micro-cathode arc thrusters, with a focus on papers published in this field in the last 5 years. In light of the development of the micro-cathode arc thruster and the latest research, the direction of future development and the application of key technologies are reviewed. Future micro-cathode arc propulsion systems are expected to exhibit higher reliability, longer lifetimes, higher specific impact, greater integration and higher thrust and to be operated in various modes. [ABSTRACT FROM AUTHOR]

The objective of this study is to investigate the effect of pulse frequency on the discharge characteristics of a micro-cathode arc thruster. We used an intensified charge-coupled device (ICCD) and high-resolution spectrometer to capture the plasma emission process of a micro-cathode arc thruster. The change in the valence ion ratio under different discharge frequencies of the thruster is studied with respect to the change in light intensity. The relationship between the pulse frequency and Ti + ion ratio, cathode emission plasma bunch velocity, and normalized thrust are studied. The spectral and electrical test results demonstrate that the proportion of high-energy ions emitted from the cathode increases with the increase in interpole discharge frequency, and the ion bunch velocity and normalized thrust of the thruster are both improved. • The effect of pulse frequency on the discharge characteristics of the thruster is studied. • The electrical and spectroscopic diagnosis results of the micro-cathode arc thruster are given. • The change of pulse frequency will affect the arc background pressure and thus affect the arc concentration. • The increase in arc concentration leads to an increase in the proportion of high-energy ions emitted by the cathode. [ABSTRACT FROM AUTHOR]

In this study, a high-speed camera was used to capture the ionization process of a Hall thruster with slits on the side of its discharge channel, and the change in light intensity was used to study ionization variations in the thruster channel. The light intensity was distributed along the axis, following a normal distribution. The peak position of the ionization intensity, ionization width fluctuation, and low-frequency oscillation of the Hall thruster was investigated. Experiments and simulations show that the oscillation frequency of the peak position of ionization intensity and the width of the main ionization zone are the same as the frequency of low-frequency oscillations. When discharge current increases, the peak position of ionization intensity moves towards the channel exit and the ionization width narrows during the decay of discharge current oscillations. Moreover, theoretical analyses show that the characteristics of the ionization distribution in the channel under a low-frequency-oscillation time scale are primarily governed by the ionization and supplementation of the mass flow rate. • The plasma distribution image in the inner channel of the Hall thruster is studied. • The discharge situation of the Hall thruster under low frequency oscillation is given. • The channel ionization parameters in the Hall thruster change periodically. • There is a coupling relationship between channel ionization in Hall thruster and low frequency oscillation. [ABSTRACT FROM AUTHOR]