At the late stage of continuous casting（CC）ladle teeming,sink vortex can suck the liquid slag into tundish,and cause negative influences on the cleanliness of molten steel.To address this issue,a twophase fluid mech...At the late stage of continuous casting（CC）ladle teeming,sink vortex can suck the liquid slag into tundish,and cause negative influences on the cleanliness of molten steel.To address this issue,a twophase fluid mechanical modeling method for ladle teeming was proposed.Firstly,a dynamic model for vortex suction process was built,and the profiles of vortex flow field were acquired.Then,based on the level set method（LSM）,a two-phase 3Dinterface coupling model for slag entrapment was built.Finally,in combination with high-order essentially non-oscillatory（ENO）and total variation diminishing（TVD）methods,a LSM-based numerical solution method was proposed to obtain the 3Dcoupling evolution regularities in vortex suction process.Numerical results show that the vortex with higher kinetic energy can form an expanded sandglass-shape region with larger slag fraction and lower rotating velocity;there is a pressure oscillation phenomenon at the vortex penetration state,which is caused by the energy shock of two-phase vortex penetration coupling.展开更多
A sink vortex is a common physical phenomenon in continuous casting,chemical extraction,water conservancy,and other industrial processes,and often causes damage and loss in production.Therefore,the real-time monitorin...A sink vortex is a common physical phenomenon in continuous casting,chemical extraction,water conservancy,and other industrial processes,and often causes damage and loss in production.Therefore,the real-time monitoring of the sink vortex state is important for improving industrial production efficiency.However,its suction-extraction phenomenon and shock vibration characteristics in the course of its formation are complex mechanical dynamic factors for flow field state monitoring.To address this issue,we set up a multi-physics model using the level set method(LSM)for a free sink vortex to study the two-phase interaction mechanism.Then,a fluid–solid coupling dynamic model was deduced to investigate the shock vibration characteristics and reveal the transition mechanism of the critical flow state.The numerical results show that the coupling energy shock induces a pressure oscillation phenomenon,which appears to be a transient enhancement of vibration at the vortex penetration state.The central part of the transient enhancement signal is a high-frequency signal.Based on the dynamic coupling model,an experimental observation platform was established to verify the accuracy of the numerical results.The water-model experiment results were accordant with the numerical results.The above results provide a reference for fluid state recognition and active vortex control for industrial monitoring systems,such as those in aerospace pipe transport,hydropower generation,and microfluidic devices.展开更多
大跨桥梁多模态涡激振动控制受限于传统线性吸振器的窄频特性。非线性能量阱惯容器(nonlinear energy sink inerter,NESI)结合宽频吸振与质量放大效应,具备多模态控制潜力,但其性能易受自质量、装配误差等附加位移影响。针对桥梁风致多...大跨桥梁多模态涡激振动控制受限于传统线性吸振器的窄频特性。非线性能量阱惯容器(nonlinear energy sink inerter,NESI)结合宽频吸振与质量放大效应,具备多模态控制潜力,但其性能易受自质量、装配误差等附加位移影响。针对桥梁风致多模态涡激振动控制,提出基于NESI的控制方法。通过理论分析与数值模拟,研究了附加位移效应对NESI控制性能的影响。研究表明,附加位移导致NESI刚度与阻尼的有效参数范围偏移,引发1∶2次频率比共振,涡激振动抑制效率降低53.7%。此外,相较于阻尼比,NESI的控制性能对桥梁模态频率和初始激励幅值更为敏感。当存在附加位移时,NESI控制性能对频率比和激励幅值变化均表现出显著退化,尤其在频率比小于1区域内性能波动剧烈。进一步研究表明,适当提高质量比与惯质比虽可在一定程度上缓解附加位移带来的性能损失,但在频率比小于1的条件下仍难以实现稳定控制。展开更多
研究了大型导管架平台卧式建造时出现单边约束圆管的风致涡激振动问题。将建造过程中单边约束的导管架圆管简化成悬臂梁模型,采用van der Pol尾流振子模型模拟圆管受到的流体力,建立了圆管风致涡激振动动力学方程。使用伽辽金方法对建...研究了大型导管架平台卧式建造时出现单边约束圆管的风致涡激振动问题。将建造过程中单边约束的导管架圆管简化成悬臂梁模型,采用van der Pol尾流振子模型模拟圆管受到的流体力,建立了圆管风致涡激振动动力学方程。使用伽辽金方法对建立的运动方程进行求解,数值分析了圆管在特定约化风速下的涡激振动特性。在圆管上附加非线性能量阱(NES)作为被动减振装置对圆管进行减振,并采用粒子群优化算法对NES的非线性刚度和阻尼参数进行了优化。结果表明,在约化速度为4.8时,得到的NES优化的非线性刚度和阻尼参数组合可以有效减小悬臂梁自由端风致涡激振动位移。本研究说明采用NES和粒子群优化算法可以有效减小圆管的风致涡激振动,为导管架安全建造提供一定的参考。展开更多
为了抑制柱体结构的涡激振动(Vortex induced vibration,VIV)问题,该文基于Van der Pol尾流振子模型、结构动力学理论和优化算法,建立了非线性能量阱(Nonlinear energy sink,NES)减振装置优化设计仿真模型。采用Van der Pol尾流振子模型...为了抑制柱体结构的涡激振动(Vortex induced vibration,VIV)问题,该文基于Van der Pol尾流振子模型、结构动力学理论和优化算法,建立了非线性能量阱(Nonlinear energy sink,NES)减振装置优化设计仿真模型。采用Van der Pol尾流振子模型,将其与二维弹性支撑柱体结构动力学方程结合,建立二维弹性支撑柱体单自由度涡激振动预报模型,并与文献实验数据对比,验证了模型的准确性;在模型中嵌入NES控制模型,完成NES作用下的单自由度柱体VIV预测模型,并将其与优化算法相结合,通过优化算法改变非线性能量阱的参数,设计出对柱体涡激振动抑制效果满足设计要求的非线性能量阱;通过仿真分析优化后的NES结构参数对柱体涡激振动的抑制效果和机理。案例优化结果表明,在Ur=5.5时,NES作用下的柱体振幅减小了66.39%,减振效果明显。同时,该文采用优化方法获得的NES结构参数符合实际生产要求,确保了实物生产设计的可能性。展开更多
基金supported by NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Informatization(U1509212)National Natural Science Foundation of China(51375446)Zhejiang Provincial Natural Science Foundation for Distinguished Young Scientists(LR16E050001)
文摘At the late stage of continuous casting（CC）ladle teeming,sink vortex can suck the liquid slag into tundish,and cause negative influences on the cleanliness of molten steel.To address this issue,a twophase fluid mechanical modeling method for ladle teeming was proposed.Firstly,a dynamic model for vortex suction process was built,and the profiles of vortex flow field were acquired.Then,based on the level set method（LSM）,a two-phase 3Dinterface coupling model for slag entrapment was built.Finally,in combination with high-order essentially non-oscillatory（ENO）and total variation diminishing（TVD）methods,a LSM-based numerical solution method was proposed to obtain the 3Dcoupling evolution regularities in vortex suction process.Numerical results show that the vortex with higher kinetic energy can form an expanded sandglass-shape region with larger slag fraction and lower rotating velocity;there is a pressure oscillation phenomenon at the vortex penetration state,which is caused by the energy shock of two-phase vortex penetration coupling.
基金supported by the National Natural Science Foundation of China(Nos.52175124 and 52305139)the Zhejiang Provincial Natural Science Foundation of China(No.LZ21E050003)+1 种基金the Fundamental Research Funds for the Zhejiang Provincial Universities(No.RF-C2020004)the Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems(No.GZKF-202125),China.
文摘A sink vortex is a common physical phenomenon in continuous casting,chemical extraction,water conservancy,and other industrial processes,and often causes damage and loss in production.Therefore,the real-time monitoring of the sink vortex state is important for improving industrial production efficiency.However,its suction-extraction phenomenon and shock vibration characteristics in the course of its formation are complex mechanical dynamic factors for flow field state monitoring.To address this issue,we set up a multi-physics model using the level set method(LSM)for a free sink vortex to study the two-phase interaction mechanism.Then,a fluid–solid coupling dynamic model was deduced to investigate the shock vibration characteristics and reveal the transition mechanism of the critical flow state.The numerical results show that the coupling energy shock induces a pressure oscillation phenomenon,which appears to be a transient enhancement of vibration at the vortex penetration state.The central part of the transient enhancement signal is a high-frequency signal.Based on the dynamic coupling model,an experimental observation platform was established to verify the accuracy of the numerical results.The water-model experiment results were accordant with the numerical results.The above results provide a reference for fluid state recognition and active vortex control for industrial monitoring systems,such as those in aerospace pipe transport,hydropower generation,and microfluidic devices.
文摘大跨桥梁多模态涡激振动控制受限于传统线性吸振器的窄频特性。非线性能量阱惯容器(nonlinear energy sink inerter,NESI)结合宽频吸振与质量放大效应,具备多模态控制潜力,但其性能易受自质量、装配误差等附加位移影响。针对桥梁风致多模态涡激振动控制,提出基于NESI的控制方法。通过理论分析与数值模拟,研究了附加位移效应对NESI控制性能的影响。研究表明,附加位移导致NESI刚度与阻尼的有效参数范围偏移,引发1∶2次频率比共振,涡激振动抑制效率降低53.7%。此外,相较于阻尼比,NESI的控制性能对桥梁模态频率和初始激励幅值更为敏感。当存在附加位移时,NESI控制性能对频率比和激励幅值变化均表现出显著退化,尤其在频率比小于1区域内性能波动剧烈。进一步研究表明,适当提高质量比与惯质比虽可在一定程度上缓解附加位移带来的性能损失,但在频率比小于1的条件下仍难以实现稳定控制。
文摘研究了大型导管架平台卧式建造时出现单边约束圆管的风致涡激振动问题。将建造过程中单边约束的导管架圆管简化成悬臂梁模型,采用van der Pol尾流振子模型模拟圆管受到的流体力,建立了圆管风致涡激振动动力学方程。使用伽辽金方法对建立的运动方程进行求解,数值分析了圆管在特定约化风速下的涡激振动特性。在圆管上附加非线性能量阱(NES)作为被动减振装置对圆管进行减振,并采用粒子群优化算法对NES的非线性刚度和阻尼参数进行了优化。结果表明,在约化速度为4.8时,得到的NES优化的非线性刚度和阻尼参数组合可以有效减小悬臂梁自由端风致涡激振动位移。本研究说明采用NES和粒子群优化算法可以有效减小圆管的风致涡激振动,为导管架安全建造提供一定的参考。
基金Project supported by the National Natural Science Foundation of China(No.51775501)the Zhejiang Provincial Natural Science Foundation of China(No.LR16E050001)
文摘为了抑制柱体结构的涡激振动(Vortex induced vibration,VIV)问题,该文基于Van der Pol尾流振子模型、结构动力学理论和优化算法,建立了非线性能量阱(Nonlinear energy sink,NES)减振装置优化设计仿真模型。采用Van der Pol尾流振子模型,将其与二维弹性支撑柱体结构动力学方程结合,建立二维弹性支撑柱体单自由度涡激振动预报模型,并与文献实验数据对比,验证了模型的准确性;在模型中嵌入NES控制模型,完成NES作用下的单自由度柱体VIV预测模型,并将其与优化算法相结合,通过优化算法改变非线性能量阱的参数,设计出对柱体涡激振动抑制效果满足设计要求的非线性能量阱;通过仿真分析优化后的NES结构参数对柱体涡激振动的抑制效果和机理。案例优化结果表明,在Ur=5.5时,NES作用下的柱体振幅减小了66.39%,减振效果明显。同时,该文采用优化方法获得的NES结构参数符合实际生产要求,确保了实物生产设计的可能性。
