基于故障树的某型船主冷凝器真空偏低原因分析

主冷凝器是船舶蒸汽动力装置的重要组成部分,其可靠性的好坏直接影响了整个蒸汽动力装置系统的运行状况。在分析了引起主冷凝器真空偏低的原因的基础上,利用故障树理论绘制出主冷凝器真空偏低故障树,并对其进行了定性分析。所得结果有助于装备使用人员和工厂技术人员更快更准地查找故障原因。     

Constructal design of tree-shaped microchannel disc heat sink with wavy walls北大核心CSCD

［Objective］To meet the efficient thermal management needs of electronic devices such as ships and underwater vehicles, this study focuses on the constructal design of a tree-shaped microchannel disc heat sink with wavy walls. ［Method］A design prototype of the heat sink with wavy walls is first proposed. Based on constructal theory, the amplitude and wavelength of the wavy walls are designed under the constraints of fixed heat sink volume and fixed microchannel volume by maximizing the comprehensive performance evaluation criteria (PEC) while considering both heat transfer and flow pressure drop. ［Results］The results show that the wavy walls increase the heat transfer surface areas and generate vortices in their cavities, effectively reducing the maximum temperature. When the inlet Reynolds number is fixed at 700, 900 or 1100 respectively, the maximum temperature is reduced by 13.5 K by increasing the amplitude of the wavy walls, while the pressure drop increases significantly; and the maximum temperature is reduced by 4.7 K by reducing the wavelength of the wavy walls, while the pressure drop increases slightly. There are optimal amplitudes that raise the comprehensive performance evaluation criteria to extreme values for given larger wavelengths, while the comprehensive performance evaluation criteria increase monotonously as the amplitude increases for given smaller wavelengths. ［Conclusion］Wavy walls can significantly improve the thermal performance of tree-shaped microchannel disc heat sinks, and the use of constructal design can realize optimal geometric constructs with optimal comprehensive performance evaluation criteria. © 2023 Authors. All rights reserved.