A mixture theory is developed for multi-component micropolar porous media with a combination of the hybrid mixture theory and the micropolar continuum theory. The system is modeled as multi-component micropolar elasti...A mixture theory is developed for multi-component micropolar porous media with a combination of the hybrid mixture theory and the micropolar continuum theory. The system is modeled as multi-component micropolar elastic solids saturated with multi- component micropolar viscous fluids. Balance equations are given through the mixture theory. Constitutive equations are developed based on the second law of thermodynamics and constitutive assumptions. Taking account of compressibility of solid phases, the volume fraction of fluid as an independent state variable is introduced in the free energy function, and the dynamic compatibility condition is obtained to restrict the change of pressure difference on the solid-fluid interface. The constructed constitutive equations are used to close the field equations. The linear field equations are obtained using a linearization procedure, and the micropolar thermo-hydro-mechanical component transport model is established. This model can be applied to practical problems, such as contaminant, drug, and pesticide transport. When the proposed model is supposed to be porous media, and both fluid and solid are single-component, it will almost agree with Eringen＇s model.展开更多
大型风力机的气动载荷、惯性力和弹性力等交变载荷会引起柔性风轮、塔架等构件的耦合振动,影响风力机性能和使用寿命。针对水平轴风力机的气弹耦合数学模型的建立及其数值积分方法进行研究。采用能反映弹性变形的超级单元(Super-element...大型风力机的气动载荷、惯性力和弹性力等交变载荷会引起柔性风轮、塔架等构件的耦合振动,影响风力机性能和使用寿命。针对水平轴风力机的气弹耦合数学模型的建立及其数值积分方法进行研究。采用能反映弹性变形的超级单元(Super-element,SE)将柔性构件离散为带有力元弹簧和阻尼器的旋转铰连接的有限个数的刚体。基于多体系统(Multi-body system,MBS)动力学理论和混合多体系统(Hybrid multi-body systems,HMBS)的建模方法,通过编制的仿真程序自动建立受约束的风力机多体系统动力学方程并进行数值求解。通过傅里叶谱分析方法,实现了系统动力学特性分析。算例分析美国可再生能源实验室(National renewable energy laboratory,NREL)公布的5 MW水平轴近海风力机的固有频率与振型,验证了程序的有效性和建模方法的正确性。基于叶素动量(Blade element momentum,BEM)理论,计算叶片变形状态下各刚体所受的气动力,在数值积分过程中实时实现流固之间的耦合。分析结果表明超级单元能用较少的自由度准确地描述风力机气动载荷、惯性力和弹性力三者之间的耦合。所开发的仿真程序能为风力机气弹耦合及稳定性分析和控制系统设计提供实用的分析平台。展开更多
基金supported by the National Natural Science Foundation of China (No.50778013)the Natural Science Foundation of Beijing (No.8082020)
文摘A mixture theory is developed for multi-component micropolar porous media with a combination of the hybrid mixture theory and the micropolar continuum theory. The system is modeled as multi-component micropolar elastic solids saturated with multi- component micropolar viscous fluids. Balance equations are given through the mixture theory. Constitutive equations are developed based on the second law of thermodynamics and constitutive assumptions. Taking account of compressibility of solid phases, the volume fraction of fluid as an independent state variable is introduced in the free energy function, and the dynamic compatibility condition is obtained to restrict the change of pressure difference on the solid-fluid interface. The constructed constitutive equations are used to close the field equations. The linear field equations are obtained using a linearization procedure, and the micropolar thermo-hydro-mechanical component transport model is established. This model can be applied to practical problems, such as contaminant, drug, and pesticide transport. When the proposed model is supposed to be porous media, and both fluid and solid are single-component, it will almost agree with Eringen＇s model.
文摘大型风力机的气动载荷、惯性力和弹性力等交变载荷会引起柔性风轮、塔架等构件的耦合振动,影响风力机性能和使用寿命。针对水平轴风力机的气弹耦合数学模型的建立及其数值积分方法进行研究。采用能反映弹性变形的超级单元(Super-element,SE)将柔性构件离散为带有力元弹簧和阻尼器的旋转铰连接的有限个数的刚体。基于多体系统(Multi-body system,MBS)动力学理论和混合多体系统(Hybrid multi-body systems,HMBS)的建模方法,通过编制的仿真程序自动建立受约束的风力机多体系统动力学方程并进行数值求解。通过傅里叶谱分析方法,实现了系统动力学特性分析。算例分析美国可再生能源实验室(National renewable energy laboratory,NREL)公布的5 MW水平轴近海风力机的固有频率与振型,验证了程序的有效性和建模方法的正确性。基于叶素动量(Blade element momentum,BEM)理论,计算叶片变形状态下各刚体所受的气动力,在数值积分过程中实时实现流固之间的耦合。分析结果表明超级单元能用较少的自由度准确地描述风力机气动载荷、惯性力和弹性力三者之间的耦合。所开发的仿真程序能为风力机气弹耦合及稳定性分析和控制系统设计提供实用的分析平台。
