Model updating for aircraft in a high temperature environment(HTE)is proposed based on the hierarchical method.With this method,the problem can be decomposed into temperature field updating and dynamic structural upda...Model updating for aircraft in a high temperature environment(HTE)is proposed based on the hierarchical method.With this method,the problem can be decomposed into temperature field updating and dynamic structural updating.In order to improve the estimation accuracy,the model updating problem is turned into a multi-objective optimization problem by constructing the objective function which combined with residues of modal frequency and effective modal mass.Then the metamodeling,support vector regression(SVR)is introduced to improve the optimization efficiency,and the solution can be determined by adaptive weighted-sum method(AWS).Finally,the proposed method is tested on a finite element(FE)model of a reentry vehicle model.The results show that the multi-objective model updating method in HTE can identify the input parameters of the temperature field and structure with good accuracy.展开更多
针对燃料电池汽车(Fuel cell vehicle,FCV)动力控制模块(Power control unit,PCU)的液冷冷板,提出15种改进结构方案。这些方案在冷板的3个高热流密度区域A、B、C中,布置不同直径、高度以及肋柱间距的圆形或椭圆形扰流阵列,以期在尽量小...针对燃料电池汽车(Fuel cell vehicle,FCV)动力控制模块(Power control unit,PCU)的液冷冷板,提出15种改进结构方案。这些方案在冷板的3个高热流密度区域A、B、C中,布置不同直径、高度以及肋柱间距的圆形或椭圆形扰流阵列,以期在尽量小的流动损失下,增强换热性能,降低冷板温度。为研究不同强化结构对3个散热区及冷板整体流动和换热性能的影响,本文对无肋柱,光滑通道的方案0以及15种改进方案进行数值模拟。在此基础上,以方案0为参考对象,运用换热强度和压降涨幅,分别表示改进方案的换热强化、压降升高程度。引入性能评估系数PEF,用以评比各个方案的流动、换热综合性能。评价结果表明,在相同的热负荷,入口流速和入口温度下,在散热区A,方案15具有最佳的传热流动综合性能;在散热区B和C,方案12表现了最好的综合冷却效果。考虑到冷板整体的壁面温度、传热效果及流动损失,PCU冷却的最佳选择为方案12。展开更多
Three types of FeMnCrAl/Cr3C2 coatings with different AI content were deposited on 20# steel substrates by the high velocity arc spraying （HVAS） process. Surface microstructures of the coatings were analyzed by opti...Three types of FeMnCrAl/Cr3C2 coatings with different AI content were deposited on 20# steel substrates by the high velocity arc spraying （HVAS） process. Surface microstructures of the coatings were analyzed by optical microscopy （OM） and X-ray diffractometry （XRD）. High temperature erosion （HTE） tests were performed in an erosion tester at different impact angles. The surface morphologies of the eroded coatings were observed on a field emission scanning electron microscope（FE-SEM）. The laminated structure is found on all the prepared coatings with the porosity and oxide fraction in the coatings decreasing with the Al content from 0 to 15% （mass fraction）. Sample FA3 with 15% Al, possessing the lowest porosity and oxide fraction, has the best HTE resistance, which demonstrates that Al addition can improve the HTE resistance of the coatings. The erosion rate of sample FA1 exhibits a maximum value at 90° impact angle. The maximum erosion rates of both FA2 and FA3 samples appear in the range of 60°-90° impact angles. Erosion loss of the coatings occurs through brittle breaking, cutting and fatigue spalling.展开更多
基金supported by the National Natural Science Foundation of China(No.11472132)the Fundamental Research Funds for Central University (No. NJ20160050)the Fundamental Research Funds for Central University(No.NJ2016098)
文摘Model updating for aircraft in a high temperature environment(HTE)is proposed based on the hierarchical method.With this method,the problem can be decomposed into temperature field updating and dynamic structural updating.In order to improve the estimation accuracy,the model updating problem is turned into a multi-objective optimization problem by constructing the objective function which combined with residues of modal frequency and effective modal mass.Then the metamodeling,support vector regression(SVR)is introduced to improve the optimization efficiency,and the solution can be determined by adaptive weighted-sum method(AWS).Finally,the proposed method is tested on a finite element(FE)model of a reentry vehicle model.The results show that the multi-objective model updating method in HTE can identify the input parameters of the temperature field and structure with good accuracy.
文摘针对燃料电池汽车(Fuel cell vehicle,FCV)动力控制模块(Power control unit,PCU)的液冷冷板,提出15种改进结构方案。这些方案在冷板的3个高热流密度区域A、B、C中,布置不同直径、高度以及肋柱间距的圆形或椭圆形扰流阵列,以期在尽量小的流动损失下,增强换热性能,降低冷板温度。为研究不同强化结构对3个散热区及冷板整体流动和换热性能的影响,本文对无肋柱,光滑通道的方案0以及15种改进方案进行数值模拟。在此基础上,以方案0为参考对象,运用换热强度和压降涨幅,分别表示改进方案的换热强化、压降升高程度。引入性能评估系数PEF,用以评比各个方案的流动、换热综合性能。评价结果表明,在相同的热负荷,入口流速和入口温度下,在散热区A,方案15具有最佳的传热流动综合性能;在散热区B和C,方案12表现了最好的综合冷却效果。考虑到冷板整体的壁面温度、传热效果及流动损失,PCU冷却的最佳选择为方案12。
基金Project(2009C31129) supported by the Science and Technology Department of Zhejiang Province, China
文摘Three types of FeMnCrAl/Cr3C2 coatings with different AI content were deposited on 20# steel substrates by the high velocity arc spraying （HVAS） process. Surface microstructures of the coatings were analyzed by optical microscopy （OM） and X-ray diffractometry （XRD）. High temperature erosion （HTE） tests were performed in an erosion tester at different impact angles. The surface morphologies of the eroded coatings were observed on a field emission scanning electron microscope（FE-SEM）. The laminated structure is found on all the prepared coatings with the porosity and oxide fraction in the coatings decreasing with the Al content from 0 to 15% （mass fraction）. Sample FA3 with 15% Al, possessing the lowest porosity and oxide fraction, has the best HTE resistance, which demonstrates that Al addition can improve the HTE resistance of the coatings. The erosion rate of sample FA1 exhibits a maximum value at 90° impact angle. The maximum erosion rates of both FA2 and FA3 samples appear in the range of 60°-90° impact angles. Erosion loss of the coatings occurs through brittle breaking, cutting and fatigue spalling.
