scholarly journals Development and testing of a three-section pulse-forming network and its application to Marx circuit

2019 ◽  
Vol 37 (4) ◽  
pp. 408-414
Author(s):  
Falun Song ◽  
Beizhen Zhang ◽  
Chunxia Li ◽  
Fei Li ◽  
Ganping Wang ◽  
...  
Keyword(s):  
Rise Time ◽  
Design Parameters ◽  
Marx Generator ◽  
Output Waveform ◽  
Pulse Forming Network ◽  
Multi Stage ◽  
Output Peak Power ◽  
In Series ◽  
Type C ◽  
Compact Design

AbstractA three-section pulse forming network (PFN) based on Guillemin type-C circuit was developed to meet the challenge of a compact design, high withstand voltage, and high-quality output waveform with fast rise time, flat-top duration, and 100-ns pulse width. A simplified pulse forming circuit was proposed and studied that includes only three LC-sections connected in parallel, with each section containing an inductor and a capacitor connected in series. The effect of the capacitance deviation on the output waveform was investigated. The simulation results show that when the capacitance deviation exceeds +3%, both the flat top and fall time of the output waveform of single PFN module deteriorate greatly. Fortunately, in a multi-stage PFN-Marx circuit, even if the capacitance deviation exceeds +10%, when the average capacitance of the same LC sections is close to the theoretical value, the output waveform maintains a good quality and is in good agreement with the theoretical prediction. The compact three-section PFN developed during this project has a size of only 360 mm × 342 mm × 65 mm, and a maximum withstand voltage of 120 kV. Sixteen PFN stages were assembled to form a Marx generator with design parameters to provide of an output peak power of 12 GW and a maximum peak current of 15 kA. The tested output waveform agrees well with the theoretical results, having a rise time of 31 ns, a flat-top of 104 ns, and a pulse with of 164 ns.

scholarly journals Research of the anti-resonance pulse forming network and its application in the Marx generator

2016 ◽  
Vol 34 (4) ◽  
pp. 675-686 ◽  
Author(s):  
Z.-L. Pan ◽  
J.-H. Yang ◽  
X.-B. Cheng
Keyword(s):  
Equivalent Circuit ◽  
Rise Time ◽  
Pulse Width ◽  
Marx Generator ◽  
Full Width ◽  
Half Maximum ◽  
Compact Structure ◽  
Fall Time ◽  
Pulse Forming Network ◽  
Load Pulse

AbstractAn anti-resonance pulse forming network (PFN) has been designed, analyzed, and tested for its application in generating quasi-square pulses. According to the circuit simulations, a compact generator based on two/three-section network was constructed. Two-section network is applied in the generator due to its compact structure, while three-section network is employed for generating pulses with higher quality. When two-section network is applied in the generator, the full-width at half-maximum of the load pulse is 400 ns, at the same time, its rise time, flat top and fall time are 90, 180 and 217 ns, respectively. When the three-section network is applied with the same pulse width of the load pulse, the rise time of the output decreases to 60 ns, while the flat top increases to 240 ns and the fall time reduces to 109 ns. Meanwhile, this kind of network could be used to shape the output pulses of generators whose equivalent circuit is LC series discharge network, such as MARX generator, into quasi-square pulses. And the preliminary experiment demonstrates that anti-resonance network could work well on four-stage Marx generators. A sine pulse generated by the four-stage Marx generator is shaped into a quasi-square pulse with voltage of 11.8 kV and pulse width about 110 ns based on two-section anti-resonance network.

scholarly journals A coaxial-output rolled strip pulse forming line based on multi-layer films

2018 ◽  
Vol 36 (1) ◽  
pp. 69-75 ◽  
Author(s):  
Jian-Cang Su ◽  
Rui Li ◽  
Jie Cheng ◽  
Bin-Xiong Yu ◽  
Xi-Bo Zhang ◽  
...  
Keyword(s):  
Rise Time ◽  
Axial Direction ◽  
Output Pulse ◽  
Rolled Strip ◽  
Strip Line ◽  
Matched Load ◽  
Multi Stage ◽  
Output Electrode ◽  
In Series ◽  
Discharging Characteristic

AbstractA coaxial-output rolled strip pulse-forming line (RSPFL) with a dry structure is researched for the purpose of miniaturization and all-solid state of pulse-forming lines (PFL). The coaxial-output RSPFL consists of a coaxial-output electrode (COE) and a rolled strip line (RSL). The COE is characterized by quasi-coaxial structure, making the output pulse propagate along the axial direction with a small output inductance. The RSL is rolled on the COE, whose transmission characteristics are analyzed theoretically. It shows that the RSL can be regarded as a planar strip line when the rolling radius of the strip line is larger than 60 times of the thickness of the insulation dielectric layer of RSL. CST modeling was carried out to simulate the discharging characteristic of the coaxial-output RSPFL. It shows that the coaxial-output RSPFL can deliver a discharging pulse with a rise time <6 ns when the impedance of the RSL matches that of the COE, which confirms the theoretical analysis. A prototype of the coaxial-output RSPFL was developed. A 49-kV discharging pulse on a matched load was achieved when it was charged to 100 kV. The discharging waveform has a pulse width of 32 ns, with a rise time of 6 ns, which is consistent with the simulation waveform. An energy-storage density of 1.9 J/L was realized in the coaxial-output RSPFL. By the method of multi-stage connection in series, a much higher output voltage is convenient to be obtained.

Conjugate Heat Transfer and Film Cooling of a Multi-Stage Cooling Scheme

2008 ◽  
Author(s):  
M. Ghorab ◽  
S. I. Kim ◽  
I. Hassan
Keyword(s):  
Heat Transfer ◽  
Film Cooling ◽  
Gas Turbines ◽  
Conjugate Heat Transfer ◽  
Density Ratio ◽  
Design Parameters ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Multi Stage ◽  
Internal Gap

Cooling techniques play a key role in improving efficiency and power output of modern gas turbines. The conjugate technique of film and impingement cooling schemes is considered in this study. The Multi-Stage Cooling Scheme (MSCS) involves coolant passing from inside to outside turbine blade through two stages. The first stage; the coolant passes through first hole to internal gap where the impinging jet cools the external layer of the blade. Finally, the coolant passes through the internal gap to the second hole which has specific designed geometry for external film cooling. The effect of design parameters, such as, offset distance between two-stage holes, gap height, and inclination angle of the first hole, on upstream conjugate heat transfer rate and downstream film cooling effectiveness performance are investigated computationally. An Inconel 617 alloy with variable properties is selected for the solid material. The conjugate heat transfer and film cooling characteristics of MSCS are analyzed across blowing ratios of Br = 1 and 2 for density ratio, 2. This study presents upstream wall temperature distributions due to conjugate heat transfer for different gap design parameters. The maximum film cooling effectiveness with upstream conjugate heat transfer is less than adiabatic film cooling effectiveness by 24–34%. However, the full coverage of cooling effectiveness in spanwise direction can be obtained using internal cooling with conjugate heat transfer, whereas adiabatic film cooling effectiveness has narrow distribution.

Effect of design parameters on stresses occurring at the tooth root in a spur gear pressed on a shaft

2021 ◽  
pp. 095440892199529
Author(s):  
Fatih Güven
Keyword(s):  
Internal Pressure ◽  
Tangential Stress ◽  
Spur Gear ◽  
Design Parameters ◽  
Interference Fit ◽  
Gear Design ◽  
Compact Design ◽  
Fit Tolerance ◽  
Moderate Stress ◽  
Good Agreement

Gears are commonly used in transmission systems to adjust velocity and torque. An integral gear or an interference fit could be used in a gearbox. Integral gears are mostly preferred as driving gear for a compact design to reduce the weight of the system. Interference fit makes the replacement of damaged gear possible and re-use of the shaft compared to the integral shaft. However, internal pressure occurs between mating surfaces of the components mated. This internal pressure affects the stress distribution at the root and bottom land of the gear. In this case, gear parameters should be re-considered to assure gear life while reducing the size of the gear. In this study, interference fitted gear-shaft assembly was examined numerically. The effects of rim thickness, profile shifting, module and fit tolerance on bending stress occurring at the root of the gear were investigated to optimize gear design parameters. Finite element models were in good agreement with analytical solutions. Results showed that the rim thickness of the gear is the main parameter in terms of tangential stress occurring at the bottom land of the gear. Positive profile shifting reduces the tangential stress while the pitch diameter of the gear remains constant. Also, lower tolerance class could be selected to moderate stress for small rim thickness.

Combined destruction of ethylene glycol, formaldehyde and methanol by biological methods

2021 ◽  
pp. 40-47
Author(s):  
М.Г. Зубов ◽  
Е.В. Вильсон ◽  
В.А. Литвиненко ◽  
А.А. Кадревич
Keyword(s):  
Ethylene Glycol ◽  
Pilot Plant ◽  
Treatment Plant ◽  
Ammonium Nitrogen ◽  
Design Parameters ◽  
Specific Rate ◽  
Toxic Substances ◽  
Multi Stage ◽  
Enhanced Biodegradation ◽  
Biological Methods

Целью прикладного научного исследования является определение удельной скорости окисления токсичных органических соединений – этиленгликоля, формальдегида и метанола – сообществом микроорганизмов иммобилизованного биоценоза на носителе ЁРШ®, установленном в пилотной установке. Для достижения поставленной цели реализован многоэтапный эксперимент, позволивший определить возможность глубокой биодеградации токсичных веществ и установить необходимую концентрацию азота аммонийного в исходной сточной воде для реализации процесса биодеградации. В ходе исследования были выполнены следующие работы: определение времени выхода на режим пилотной установки после плановой остановки в подаче сточных вод на 31-й день; оценка удельной скорости окисления прикрепленным биоценозом по показателям этиленгликоль, формальдегид, ХПК, БПК; оценка ассимиляции и трансформации соединений азота; формулирование выводов на основе проведенного анализа результатов исследований, необходимых для оценки целесообразности применения биологической очистки сточных вод прикрепленным биоценозом исследуемых загрязнителей и определения расчетных параметров очистного сооружения. The objective of the applied scientific research is to determine the specific rate of oxidation of toxic organic compounds – ethylene glycol, formaldehyde and methanol – by the community of microorganisms of the immobilized biocenosis on the IORSh carrier installed in a pilot plant. To achieve this goal, a multi-stage experiment was carried out that provided for determining possible enhanced biodegradation of toxic substances and specifying the required concentration of ammonium nitrogen in raw wastewater for the implementation of the biodegradation process. In the course of the study, the following works were carried out: determining the process stabilization time in the pilot plant after the scheduled shutdown in the wastewater supply on the 31stday; assessing the specific rate of oxidation by the attached biocenosis in terms of ethylene glycol, formaldehyde, COD, BOD; assessing the assimilation and transformation of nitrogen compounds; drawing conclusions based on the analysis of the research results required for estimating the feasibility of using biological wastewater treatment with the attached biocenosis of the pollutants under study and determining the design parameters of the treatment plant.

Improving Gerotor Pump Performance Trough Design, Modeling and Simulation

2021 ◽  
Author(s):  
Lozica Ivanović ◽  
Miloš Matejić
Keyword(s):  
Low Noise ◽  
Operating Conditions ◽  
Design Parameters ◽  
Pump Efficiency ◽  
Hydraulic Systems ◽  
Wear Process ◽  
Gerotor Pump ◽  
Gerotor Pumps ◽  
Negative Effect ◽  
Compact Design

Gerotor pumps are well known by a compact design, simple structure and low noise level, which makes them suitable for use in the automotive industry, and especially in hydraulic systems for engine lubrication. One of the main disadvantages of gerotor pumps is the inability to adjust to wear, which significantly reduces the pump efficiency. In order to mitigate the negative effect of the inevitable wear process, this paper presents a methodology for determining the optimal combination of trochoid gears design parameters for a defined aspect. An appropriate mathematical model has been developed to analyze the effect of changes in gear design parameters in relation to maximum contact stresses, pressure changes in gerotor pump chambers and wear rate proportional factor (WRPF). Verification of the developed models was performed by realizing physical pairs of gears and laboratory experiments with simulation of pump operating conditions. The results and conclusions presented in this paper, with an emphasis on the actual work processes, bring very important perspectives for the gerotor pumps design with improved performance.

Development of a Pulsed Power Supply Utilizing 13 kV Class SiC-MOSFETs

2020 ◽  
Vol 1004 ◽  
pp. 1141-1147
Author(s):  
Katsuya Okamura ◽  
Fujio Naito ◽  
Ken Takayama ◽  
Hidenori Kitai ◽  
Hisato Michikoshi ◽  
...  
Keyword(s):  
Rise Time ◽  
Short Pulse ◽  
Load Resistance ◽  
Pulsed Power ◽  
Circuit Board ◽  
Resistive Load ◽  
Circuit Boards ◽  
Pulse Switching ◽  
2Nd Generation ◽  
In Series

To resolve the drawback of conventional thyratron switches, development of a semiconductor high voltage switch utilizing a 13 kV class SiC-MOSFET developed by Tsukuba Power Electronics Constellations (TPEC) is proceeding. At first, the device evaluation test was carried out with a resistive load circuit. With the conditions of drain voltage of 10 kV and load resistance of 1 kΩ, turn on loss Eon, turn off loss Eoff, rise time Tr and fall time Tf were 1.7 mJ, 1.1 mJ, 64 ns, and 75 ns, respectively. Thereafter, the 2s-12p switch array was designed and assembled, where 12 MOSFETs are equally aligned on a circle shaped circuit board and two circuit boards are stacked in series. An 18 kV-318 A-1 us pulse with a rise time of 289 ns in the short pulse switching test were successfully demonstrated. Moreover, switching tests of 2nd generation MOSFET that has a twice larger device area was conducted. As a result, 60 % reduction of on-resistance was confirmed.

Accelerated 3D Aerodynamic Optimization of Gas Turbine Blades

2014 ◽  
Author(s):  
Philipp Amtsfeld ◽  
Michael Lockan ◽  
Dieter Bestle ◽  
Marcus Meyer
Keyword(s):  
Turbine Blades ◽  
Three Dimensional ◽  
Optimization Process ◽  
Design Parameters ◽  
Blade Design ◽  
Aerodynamic Optimization ◽  
Multi Stage ◽  
Design Variables ◽  
Real Flow ◽  
Blade Model

State-of-the-art aerodynamic blade design processes mainly consist of two phases: optimal design of 2D blade sections and then stacking them optimally along a three-dimensional stacking line. Such a quasi-3D approach, however, misses the potential of finding optimal blade designs especially in the presence of strong 3D flow effects. Therefore, in this paper a blade optimization process is demonstrated which uses an integral 3D blade model and 3D CFD analysis to account for three-dimensional flow features. Special emphasis is put on shortening design iterations and reducing design costs in order to obtain a rapid automatic optimization process for fully 3D aerodynamic turbine blade design which can be applied in an early design phase already. The three-dimensional parametric blade model is determined by up to 80 design variables. At first, the most important design parameters are chosen based on a non-linear sensitivity analysis. The objective of the subsequent optimization process is to maximize isentropic efficiency while fulfilling a minimal set of constraints. The CFD model contains both important geometric features like tip gaps and fillets, and cooling and leakage flows to sufficiently represent real flow conditions. Two acceleration strategies are used to cut down the turn-around time from weeks to days. Firstly, the aerodynamic multi-stage design evaluation is significantly accelerated with a GPU-based RANS solver running on a multi-GPU workstation. Secondly, a response surface method is used to reduce the number of expensive function evaluations during the optimization process. The feasibility is demonstrated by an application to a blade which is a part of a research rig similar to the high pressure turbine of a small civil jet engine. The proposed approach enables an automatic aerodynamic design of this 3D blade on a single workstation within few days.

Low cost 400-ps rise-time circuit-board Marx generator

2011 ◽  
Author(s):  
C. Nunnally ◽  
Matthew B. Lara ◽  
J. R. Mayes ◽  
T.R. Smith
Keyword(s):  
Rise Time ◽  
Low Cost ◽  
Circuit Board ◽  
Marx Generator

scholarly journals A new kind of solid-state Marx generator based on transformer type magnetic switches

2013 ◽  
Vol 31 (2) ◽  
pp. 239-248 ◽  
Author(s):  
Yu Zhang ◽  
Jinliang Liu
Keyword(s):  
Solid State ◽  
Life Time ◽  
Input Voltage ◽  
Magnetic Core ◽  
Marx Generator ◽  
Magnetic Switch ◽  
Transformer Type ◽  
In Series ◽  
New Type ◽  
High Level

AbstractIn this paper, a new kind of solid-state Marx generator based on synchronous transformer type magnetic switches (TTMS) is put forward, and the TTMSs with new winding structures are used to substitute all the spark gaps in the traditional Marx generator for the purposes of solidification and long life time. As the new type of TTMS with high step-up ratio and low saturated inductances is employed, the proposed Marx generator becomes a compact combination of pulse transformer, magnetic switch, and Marx capacitors. The stages of the Marx capacitors can be synchronously charged in parallel before the magnetic core saturates, and these Marx capacitors also can synchronously discharge in series. The establishing time of the proposed Marx generator is at ns range. As the new type of self-reset TTMS is used, the input voltage of the Marx generator decreases to a low level less than 1 kV while the output voltage can easily reach a high level ranging from dozens of kV to hundreds of kV.

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