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- 저자 : Guitao (검색결과 3 건)
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Guitao Zeng,Qianqian Li,Peng Wu,Bo Qian,Bin Huang,Shiyang Li,Dazhuan Wu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.7
Low specific speed centrifugal pumps are widely applied in the chemical industry and agricultural irrigation fields. The vibration characteristics are of great importance for centrifugal pumps. Apart from rotor installation, fluid-induced vibrations caused by internal flow also play an important role in the vibration performance, and special attention should be paid to low specific speed centrifugal pumps for long and narrow meridian flow channels where secondary flows are easy to generate. In this paper, splitter blades were studied for decreasing the pressure and radial force fluctuations of a low specific speed centrifugal pump at the design point, both numerically and experimentally. Numerical simulations based on the Reynolds averaged Navier–Stokes (RANS) turbulent model were performed for fluid-field analysis. The steady state and unsteady simulations were computed based on ANSYS Fluent. Here, the circumferential location, leading edge location, and the deflection angle of the splitter blades were considered to suppress the secondary flow and to reduce vibration. The experiments show the effectiveness of splitter blades for decreasing fluid-induced vibrations.
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Guitao Zeng,Weibin Chen,Juanhong Li,Peng Wu,Bin Huang,Dazhuan Wu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10
Mixed-flow pumps have been widely used in water jet propulsion field. To ensure reliability and operation efficiency, it is necessary to investigate the characteristics of hydraulic excitation force during transient operations. In this paper, the radial force of a water jet mixed-flow pump during rapid startup period was investigated numerically based on improved delayed detached eddy simulation (IDDES) and siding mesh method, the external characteristics were verified by test results. The spatial-temporal evolution of radial force was analyzed. The radial force during rapid startup presents transient and delay phenomenon, which shows disparity compared with quasi-steady state. The flow analysis and blade strip analysis show inlet recirculation significantly affects the radial force’s evolution, the radial force is quite different from blade root to tip and the blade tip contributes most to the radial force delay phenomenon. By applying boundary vorticity flux (BVF) theory and separation vortex formation diagnosis, separation regions caused by the dissipation of inlet recirculation were effectively identified and the change trend is in line with the change of radial force, which explains how inlet recirculation results the delay of radial force on blade tip strip and the whole impeller blade.
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Sun, Xiangdong,Wang, Zhixuan,Zhang, Qi,Chen, Guitao The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.2
For dual-active-bridge (DAB) DC-DC converters, a variable frequency triple-phase-shift (VF-TPS) modulation strategy based on a particle swarm optimization (PSO) algorithm was proposed to solve the problem of the low efficiency of TPS modulation in larger power conditions. To facilitate the implementation of the PSO algorithm, the mathematical expressions between the transmission power or the RMS square of the inductance current and four control variables including the switching frequency and three phase-shift duty cycles are simplified by the Fourier series decomposition method. An objective function of the particle fitness is presented to find the optimal control variables at any reference transmission power, which achieves the minimum inductance RMS current in the full power range and improves the efficiency under heavy loads. In addition, the PSO algorithm is used to design the appropriate switching frequency range and inductance. Finally, a 1.2 kW DAB converter prototype was established, and experimental results verify the correctness and feasibility of the modulation strategy.
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