Under submerged conditions, compared with traditional self-excited oscillating pulsed waterjets(SOPWs), annular fluid-enhanced self-excited oscillating pulsed waterjets(AFESOPWs) exhibit a higher surge pressure throug...Under submerged conditions, compared with traditional self-excited oscillating pulsed waterjets(SOPWs), annular fluid-enhanced self-excited oscillating pulsed waterjets(AFESOPWs) exhibit a higher surge pressure through self-priming. However, their pressure frequency and cavitation characteristics remain unclear, resulting in an inability to fully utilize resonance and cavitation erosion to break coal and rock. In this study, high-frequency pressure testing, high-speed photography, and large eddy simulation(LES) are used to investigate the distribution of the pressure frequency band, evolution law of the cavitation cloud, and its regulation mechanism of a continuous waterjet, SOPW, and AFESOPW. The results indicated that the excitation of the plunger pump, shearing layer vortex, and bubble collapse corresponded to the three high-amplitude frequency bands of the waterjet pressure. AFESOPWs have an additional self-priming frequency that can produce a larger amplitude under a synergistic effect with the second high-amplitude frequency band. A better cavitation effect was produced after self-priming the annulus fluid, and the shedding frequency of the cavitation clouds of the three types of waterjets was linearly related to the cavitation number. The peak pressure of the waterjet and cavitation erosion effect can be improved by modulating the waterjet pressure oscillation frequency and cavitation shedding frequency.展开更多
The new 1 kW power module for ADS project needs the optimization of cooling design including water flow and tunnel layout, and the water flow of three tons per hour was chosen to be a goal for a 20 kW power source.Acc...The new 1 kW power module for ADS project needs the optimization of cooling design including water flow and tunnel layout, and the water flow of three tons per hour was chosen to be a goal for a 20 kW power source.According to analysis from the insertion and integrated loss, about 24 modules were integrated into the rated power. Thus, every module has a cooling flow of 2.1 L/min for RF heat load and power supply loss, which is very hard to achieve if no special consideration and techniques. A new thermal simulation method was introduced for thermal analysis of cooling plate through CST multi-physics suite,especially for temperature of power LDMOS transistor.Some specific measures carried out for the higher heat transfer were also presented in this paper.展开更多
依据欧洲电信标准协会(ETSI)提出的ETSI EN 300 401标准,设计了一种高性能DAB接收终端RF接收模块的设计方法,实现了DAB信号稳定同步和接收,达到了高灵敏度和低功耗,在移动速度达到200 km/h时能够稳定接收。该设计方法已经用于批量生产的...依据欧洲电信标准协会(ETSI)提出的ETSI EN 300 401标准,设计了一种高性能DAB接收终端RF接收模块的设计方法,实现了DAB信号稳定同步和接收,达到了高灵敏度和低功耗,在移动速度达到200 km/h时能够稳定接收。该设计方法已经用于批量生产的DAB接收终端中。展开更多
基金supported by the program for National Natural Science Foundation of China (Nos. 52174173, 52274188, and 52104190)the Joint Funds of the National Natural Science Foundation of China (No. U24A2091)+1 种基金The Natural Science Foundation of Henan Polytechnic University (No. B2021-2)Double FirstClass Initiative of Safety and Energy Engineering (Henan Polytechnic University) (Nos. AQ20240703 and AQ20230304)。
文摘Under submerged conditions, compared with traditional self-excited oscillating pulsed waterjets(SOPWs), annular fluid-enhanced self-excited oscillating pulsed waterjets(AFESOPWs) exhibit a higher surge pressure through self-priming. However, their pressure frequency and cavitation characteristics remain unclear, resulting in an inability to fully utilize resonance and cavitation erosion to break coal and rock. In this study, high-frequency pressure testing, high-speed photography, and large eddy simulation(LES) are used to investigate the distribution of the pressure frequency band, evolution law of the cavitation cloud, and its regulation mechanism of a continuous waterjet, SOPW, and AFESOPW. The results indicated that the excitation of the plunger pump, shearing layer vortex, and bubble collapse corresponded to the three high-amplitude frequency bands of the waterjet pressure. AFESOPWs have an additional self-priming frequency that can produce a larger amplitude under a synergistic effect with the second high-amplitude frequency band. A better cavitation effect was produced after self-priming the annulus fluid, and the shedding frequency of the cavitation clouds of the three types of waterjets was linearly related to the cavitation number. The peak pressure of the waterjet and cavitation erosion effect can be improved by modulating the waterjet pressure oscillation frequency and cavitation shedding frequency.
基金supported by the ‘‘strategic priority research program’’ of the Chinese Academy of Sciences(No.XDA030205)
文摘The new 1 kW power module for ADS project needs the optimization of cooling design including water flow and tunnel layout, and the water flow of three tons per hour was chosen to be a goal for a 20 kW power source.According to analysis from the insertion and integrated loss, about 24 modules were integrated into the rated power. Thus, every module has a cooling flow of 2.1 L/min for RF heat load and power supply loss, which is very hard to achieve if no special consideration and techniques. A new thermal simulation method was introduced for thermal analysis of cooling plate through CST multi-physics suite,especially for temperature of power LDMOS transistor.Some specific measures carried out for the higher heat transfer were also presented in this paper.
