为探索脉冲爆轰水冲压发动机水下工作时导水器内燃气射流发展特性,利用可燃气体的爆轰在水下受限空间内产生脉动气泡,对爆轰管在圆筒形受限空间内的水下爆轰燃气射流进行了数值仿真与实验验证。基于雷诺时均基本方程组与k-ε两方程模型...为探索脉冲爆轰水冲压发动机水下工作时导水器内燃气射流发展特性,利用可燃气体的爆轰在水下受限空间内产生脉动气泡,对爆轰管在圆筒形受限空间内的水下爆轰燃气射流进行了数值仿真与实验验证。基于雷诺时均基本方程组与k-ε两方程模型耦合流体体积气液界面追踪方法的相输运方程建立受限空间中水下单次燃气射流流场流动模型,使用OpenFOAM中的Compressible Inter Foam求解器对受限空间中脉冲爆轰燃气射流进行数值求解。结果表明:受限空间对水下爆轰的前导激波的影响较小,前导激波幅值与自由空间相比变化不大,由爆轰燃气射流所引起的压力扰动大幅升高且持续时间明显增加,受限空间中各处压力显著高于受限空间之外;受限空间中燃气泡的脉动周期延长至60 ms左右,然而受限空间径向尺寸对燃气泡的脉动周期影响较小。可见,受限空间可提高水下爆轰管出口近场压力并延长燃气射流作用时间,研究结果对脉冲爆轰水冲压发动机推力性能提升方法研究具有重要指导作用。展开更多
In the commercial utilization of rigid ceramic filters, the performance of pulse cleaning has crucial effects on the long-term stable operation. In order to get a clear insight into the nature of this cleaning process...In the commercial utilization of rigid ceramic filters, the performance of pulse cleaning has crucial effects on the long-term stable operation. In order to get a clear insight into the nature of this cleaning process and provide a solid basis for industrial applications, the flow in ceramic candle filter was investigated. The flow in the pulse-jetspace and inside the ceramic candle is regarded as two- dimensional, unsteady, compressible flow, and numerical simulation is carried out by computational fluid dynamics. The numerical predictions of flow field are in good agreement with the experimental measurements. Effects of the candle diameter, the separation distance between the nozzle and the candle injector and the length of the candle on the flowfield have been numerically analyzed to provide the basis for the optimum design of the pulse cleaning system.展开更多
High voltage pulse natural organic matter （NOM） toxic by-products. Fulvic acid discharge plasma can remove and produce no production of solution was treated by high voltage pulse discharge plasma in this paper. It w...High voltage pulse natural organic matter （NOM） toxic by-products. Fulvic acid discharge plasma can remove and produce no production of solution was treated by high voltage pulse discharge plasma in this paper. It was shown that： for the reason of thermolysis and oxidation, the pH and Oxidation Reduction Potential （ORP） of solution decreased gradually with the increase of peak voltage and fulvic acid solution concentration, meanwhile the temperature and turbidity of solution increased gradually. Adding hydrochlorid acid in the treatment could amplify the effect of plasma. When the concentration of NOM as the surrogate parameter, Ultraviolet Absorbancy Degree （UV254） increased slowly by the effect of plasma, while the degradation of Total Organic Carbon （TOC） was first-order reaction. The removal rate of TOC increased from 22.6% to 33.4% by high voltage pulse electrical field of 35 kv, and from 25.6% to 36.7% with the addition of hydrochlorid acid. This paper may provide some basis for the scale-up design of water treatment process by high voltage pulse discharge plasma with other technologies.展开更多
Investigations are directed to the development of high-power sources ofUWB （ultrawideband） radiation based on excitation of anterma arrays with bipolar voltage pulses. In the previously designed high-power UWB sourc...Investigations are directed to the development of high-power sources ofUWB （ultrawideband） radiation based on excitation of anterma arrays with bipolar voltage pulses. In the previously designed high-power UWB sources only one bipolar pulse former and different feeder systems for pulse distribution through the array elements were used. By means of this approach, a number of UWB sources were created with the bipolar voltage pulse length ranging from 0.2 to 2 ns and effective potential of radiation ranging from 0.4 to 3 MV. The approach has got a restriction related to the electrical breakdown in a bipolar voltage pulse former. A new approach to the creation of high-power UWB sources based on a multicharmel bipolar pulse former is suggested： the number of bipolar pulse formers is equal to the number of antennas in the array. The main problem in realization of this approach is a stable operation of bipolar pulse formers in order to ensure a coherent summation of radiated pulses in the far-field zone. The result of this work is the instability of-150 ps at the pulse length of 3 ns obtained in a one-channel bipolar pulse former indicating that the suggested approach is realizable.展开更多
In the research of bio-molecular chips and sensors, extra electric biases are most often employed to control and manipulate the DNA and protein molecules moving through micro/nano-fluidic channels. In order to accurat...In the research of bio-molecular chips and sensors, extra electric biases are most often employed to control and manipulate the DNA and protein molecules moving through micro/nano-fluidic channels. In order to accurately and flexibly control the bio-molecules as they move within the channels, a clear understanding of how the current changes within the buffer solution caused by an applied bias is fundamental. In this report, the current changed value of different buffer solutions, e.g., KC1, TE, and TBE was systematically studied with real-time monitoring and quantitative analysis in the situation of the buffers moving through a fluidic channel with a 5 μm inner diameter, driven by biases of 50 or 100 mV. The results revealed that the relation- ship between the current changed value and the pause interval of the applied electric field is highly consistent with the Hill Equation, which is helpful for accurately detecting and manipulating single biomolecules in microfluidic sensors and biochips.展开更多
文摘为探索脉冲爆轰水冲压发动机水下工作时导水器内燃气射流发展特性,利用可燃气体的爆轰在水下受限空间内产生脉动气泡,对爆轰管在圆筒形受限空间内的水下爆轰燃气射流进行了数值仿真与实验验证。基于雷诺时均基本方程组与k-ε两方程模型耦合流体体积气液界面追踪方法的相输运方程建立受限空间中水下单次燃气射流流场流动模型,使用OpenFOAM中的Compressible Inter Foam求解器对受限空间中脉冲爆轰燃气射流进行数值求解。结果表明:受限空间对水下爆轰的前导激波的影响较小,前导激波幅值与自由空间相比变化不大,由爆轰燃气射流所引起的压力扰动大幅升高且持续时间明显增加,受限空间中各处压力显著高于受限空间之外;受限空间中燃气泡的脉动周期延长至60 ms左右,然而受限空间径向尺寸对燃气泡的脉动周期影响较小。可见,受限空间可提高水下爆轰管出口近场压力并延长燃气射流作用时间,研究结果对脉冲爆轰水冲压发动机推力性能提升方法研究具有重要指导作用。
基金Supported by the National Natural Science Foundation of China(No.59976023)
文摘In the commercial utilization of rigid ceramic filters, the performance of pulse cleaning has crucial effects on the long-term stable operation. In order to get a clear insight into the nature of this cleaning process and provide a solid basis for industrial applications, the flow in ceramic candle filter was investigated. The flow in the pulse-jetspace and inside the ceramic candle is regarded as two- dimensional, unsteady, compressible flow, and numerical simulation is carried out by computational fluid dynamics. The numerical predictions of flow field are in good agreement with the experimental measurements. Effects of the candle diameter, the separation distance between the nozzle and the candle injector and the length of the candle on the flowfield have been numerically analyzed to provide the basis for the optimum design of the pulse cleaning system.
文摘High voltage pulse natural organic matter （NOM） toxic by-products. Fulvic acid discharge plasma can remove and produce no production of solution was treated by high voltage pulse discharge plasma in this paper. It was shown that： for the reason of thermolysis and oxidation, the pH and Oxidation Reduction Potential （ORP） of solution decreased gradually with the increase of peak voltage and fulvic acid solution concentration, meanwhile the temperature and turbidity of solution increased gradually. Adding hydrochlorid acid in the treatment could amplify the effect of plasma. When the concentration of NOM as the surrogate parameter, Ultraviolet Absorbancy Degree （UV254） increased slowly by the effect of plasma, while the degradation of Total Organic Carbon （TOC） was first-order reaction. The removal rate of TOC increased from 22.6% to 33.4% by high voltage pulse electrical field of 35 kv, and from 25.6% to 36.7% with the addition of hydrochlorid acid. This paper may provide some basis for the scale-up design of water treatment process by high voltage pulse discharge plasma with other technologies.
文摘Investigations are directed to the development of high-power sources ofUWB （ultrawideband） radiation based on excitation of anterma arrays with bipolar voltage pulses. In the previously designed high-power UWB sources only one bipolar pulse former and different feeder systems for pulse distribution through the array elements were used. By means of this approach, a number of UWB sources were created with the bipolar voltage pulse length ranging from 0.2 to 2 ns and effective potential of radiation ranging from 0.4 to 3 MV. The approach has got a restriction related to the electrical breakdown in a bipolar voltage pulse former. A new approach to the creation of high-power UWB sources based on a multicharmel bipolar pulse former is suggested： the number of bipolar pulse formers is equal to the number of antennas in the array. The main problem in realization of this approach is a stable operation of bipolar pulse formers in order to ensure a coherent summation of radiated pulses in the far-field zone. The result of this work is the instability of-150 ps at the pulse length of 3 ns obtained in a one-channel bipolar pulse former indicating that the suggested approach is realizable.
基金supported by the Major Research Plan of the National Natural Science Foundation of China(Grant No.91123030)the Interna-tional Cooperation Foundation of the National Science and Technology Major Project of the Ministry of Science and Technology of China(Grant No.2011DFA12220)the National Natural Science Foundation of China(Grant No.61378083)
文摘In the research of bio-molecular chips and sensors, extra electric biases are most often employed to control and manipulate the DNA and protein molecules moving through micro/nano-fluidic channels. In order to accurately and flexibly control the bio-molecules as they move within the channels, a clear understanding of how the current changes within the buffer solution caused by an applied bias is fundamental. In this report, the current changed value of different buffer solutions, e.g., KC1, TE, and TBE was systematically studied with real-time monitoring and quantitative analysis in the situation of the buffers moving through a fluidic channel with a 5 μm inner diameter, driven by biases of 50 or 100 mV. The results revealed that the relation- ship between the current changed value and the pause interval of the applied electric field is highly consistent with the Hill Equation, which is helpful for accurately detecting and manipulating single biomolecules in microfluidic sensors and biochips.
