A hybrid Euler/full potential/Lagrangian wake method,based on single-blade simulation,for predicting unsteady aerodynamic flow around helicopter rotors in hover and forward flight has been developed.In this method,an ...A hybrid Euler/full potential/Lagrangian wake method,based on single-blade simulation,for predicting unsteady aerodynamic flow around helicopter rotors in hover and forward flight has been developed.In this method,an Euler solver is used to model the near wake evolution and transonic flow phenomena in the vicinity of the blade,and a full potential equation（FPE） is used to model the isentropic potential flow region far away from the rotor,while the wake effects of other blades and the far wake are incorporated into the flow solution as an induced inflow distribution using a Lagrangian based wake analysis.To further reduce the execution time,the computational fluid dynamics（CFD） solution and rotor wake analysis（including induced velocity up-date） are conducted parallelly,and a load balancing strategy is employed to account for the information exchange between two solvers.By the developed method,several hover and forward-flight cases on Caradonna-Tung and Helishape 7A rotors are per-formed.Good agreements of the loadings on blade surface with available measured data demonstrate the validation of the method.Also,the CPU time required for different computation runs is compared in the paper,and the results show that the pre-sent hybrid method is superior to conventional CFD method in time cost,and will be more efficient with the number of blades increasing.展开更多
对于高超声速飞行器在临近空间形成的连续与稀薄混合流场,DSMC(direct simulation of Monte Carlo)方法需要消耗巨大的计算资源,CFD(computational fluid dynamics)方法,无法对稀薄效应进行准确模拟。在对连续/稀薄耦合数值方法深入研...对于高超声速飞行器在临近空间形成的连续与稀薄混合流场,DSMC(direct simulation of Monte Carlo)方法需要消耗巨大的计算资源,CFD(computational fluid dynamics)方法,无法对稀薄效应进行准确模拟。在对连续/稀薄耦合数值方法深入研究的基础上,提出了一套非结构网格的CFD/DSMC耦合方法。该方法具有通用强、适应性良好的特点,进行耦合计算时对不规则复杂分界面无需进行光滑处理。对超声速圆柱绕流和钝锥体流场进行了模拟,数值结果表明:该方法对不规则分界面和复杂外形具有高度适用性,通过与重叠网格结果进行比较验证了该方法的有效性和计算效率,相较于传统的DSMC方法,计算效率分别提高了2.3倍和3.16倍,具有高效性。展开更多
为研究混凝土运输车搅拌筒内的混凝土与骨料颗粒的真实运动情况,采用CFD-DEM耦合的方法,考虑混凝土的非牛顿流体特性及骨料颗粒间的相互作用,对混凝土进料、搅拌、出料过程的混凝土及颗粒运动规律进行数值模拟。通过将出料时间和出料速...为研究混凝土运输车搅拌筒内的混凝土与骨料颗粒的真实运动情况,采用CFD-DEM耦合的方法,考虑混凝土的非牛顿流体特性及骨料颗粒间的相互作用,对混凝土进料、搅拌、出料过程的混凝土及颗粒运动规律进行数值模拟。通过将出料时间和出料速率数值仿真结果与实验对比,验证了CFD-DEM耦合方法的可行性。将计算流体动力学(Computational Fluid Dynamics,CFD)和离散元(Discrete Element Method,DEM)仿真结果导入ABAQUS中对叶片结构强度进行了分析,结果表明:叶片所受应力远小于材料的许用应力,最大节点位移满足刚度设计要求。最后对叶片的磨损情况进行了分析。展开更多
基金National Natural Science Foundation of China (10872094)
文摘A hybrid Euler/full potential/Lagrangian wake method,based on single-blade simulation,for predicting unsteady aerodynamic flow around helicopter rotors in hover and forward flight has been developed.In this method,an Euler solver is used to model the near wake evolution and transonic flow phenomena in the vicinity of the blade,and a full potential equation（FPE） is used to model the isentropic potential flow region far away from the rotor,while the wake effects of other blades and the far wake are incorporated into the flow solution as an induced inflow distribution using a Lagrangian based wake analysis.To further reduce the execution time,the computational fluid dynamics（CFD） solution and rotor wake analysis（including induced velocity up-date） are conducted parallelly,and a load balancing strategy is employed to account for the information exchange between two solvers.By the developed method,several hover and forward-flight cases on Caradonna-Tung and Helishape 7A rotors are per-formed.Good agreements of the loadings on blade surface with available measured data demonstrate the validation of the method.Also,the CPU time required for different computation runs is compared in the paper,and the results show that the pre-sent hybrid method is superior to conventional CFD method in time cost,and will be more efficient with the number of blades increasing.
文摘对于高超声速飞行器在临近空间形成的连续与稀薄混合流场,DSMC(direct simulation of Monte Carlo)方法需要消耗巨大的计算资源,CFD(computational fluid dynamics)方法,无法对稀薄效应进行准确模拟。在对连续/稀薄耦合数值方法深入研究的基础上,提出了一套非结构网格的CFD/DSMC耦合方法。该方法具有通用强、适应性良好的特点,进行耦合计算时对不规则复杂分界面无需进行光滑处理。对超声速圆柱绕流和钝锥体流场进行了模拟,数值结果表明:该方法对不规则分界面和复杂外形具有高度适用性,通过与重叠网格结果进行比较验证了该方法的有效性和计算效率,相较于传统的DSMC方法,计算效率分别提高了2.3倍和3.16倍,具有高效性。
文摘为研究混凝土运输车搅拌筒内的混凝土与骨料颗粒的真实运动情况,采用CFD-DEM耦合的方法,考虑混凝土的非牛顿流体特性及骨料颗粒间的相互作用,对混凝土进料、搅拌、出料过程的混凝土及颗粒运动规律进行数值模拟。通过将出料时间和出料速率数值仿真结果与实验对比,验证了CFD-DEM耦合方法的可行性。将计算流体动力学(Computational Fluid Dynamics,CFD)和离散元(Discrete Element Method,DEM)仿真结果导入ABAQUS中对叶片结构强度进行了分析,结果表明:叶片所受应力远小于材料的许用应力,最大节点位移满足刚度设计要求。最后对叶片的磨损情况进行了分析。
