In this article, the transonic inviscid flow over a deformable airfoil with plunging motion is studied numerically. A finite volume method based on the Roe scheme developed in a generalized coordinate is used along wi...In this article, the transonic inviscid flow over a deformable airfoil with plunging motion is studied numerically. A finite volume method based on the Roe scheme developed in a generalized coordinate is used along with an arbitrary Lagrangian-Eulerian method and a dynamic mesh algorithm to track the instantaneous position of the airfoil. The effects of different governing parameters such as the phase angle, the deformation amplitude, the initial angle of attack, the flapping frequency, and the Mach number on the unsteady flow field and aerodynamic coefficients are investigated in detail. The results show that maneuverability of the airfoil under various flow conditions is improved by the deformation. In addition, as the oscillation frequency of the airfoil increases, its aerodynamic performance is significantly improved.展开更多
Based on the understanding of the mechanism of energy dissipation,a new type of plunge pool is presented with the advantages of high rate of energy dissipation,low impact pressure,and small close-to-bed velocity on th...Based on the understanding of the mechanism of energy dissipation,a new type of plunge pool is presented with the advantages of high rate of energy dissipation,low impact pressure,and small close-to-bed velocity on the soleplate of the plunge pool.The first advantage owes to enlarged shearing energy dissipation areas in the plunge pool,while the other two are caused by the jet that enters in a nearly horizontal level to keep the soleplate from being scoured directly.All of the above arrangements make this new type of energy dissipator distinct from the underflow energy dissipation.Through experiments on the physical model,the authors found that the water flow maintained stable and submerged in horizontal direction when the flow was narrow in horizontal but thick in vertical direction.However,the wide flat nappe was ready to submerge or float as the downstream water level rised or dropped.The entire flow fields of multi-horizontal submerged jets into plunge pool were also numerically simulated.The numerical results of water surface curve,close-to-bed velocity and floor pressure agree well with the experimental data.The flow pattern in the plunge pool was analyzed after combining the laboratory data and numerical simulation.展开更多
研究表深孔上下差动出流,水股分层分散射流在水垫塘的流动特征和各水股射流之间的干扰碰撞特性。选用非定常不可压缩流动的N-S方程和RNGk-ε紊流模型,采用VOF(Volume of Fluid)法结合溪洛渡双曲拱坝水垫塘对不同间距的多层二元射流进入...研究表深孔上下差动出流,水股分层分散射流在水垫塘的流动特征和各水股射流之间的干扰碰撞特性。选用非定常不可压缩流动的N-S方程和RNGk-ε紊流模型,采用VOF(Volume of Fluid)法结合溪洛渡双曲拱坝水垫塘对不同间距的多层二元射流进入水垫塘后的水流结构进行了数值模拟。通过对时间的迭代,计算和分析了水股间距对水垫塘恒定流场特性的影响,按多股射流入射水垫塘后的流动特征分为四类。给出了水股间距对水垫塘底板的冲击压力的影响规律以及与流场、速度场的关系,发现射流对水垫塘底板的冲击压力特点和速度场的分布特点相对应。研究认为:对于坝身泄洪为分层出流时,在射流入水间距能保证充分发挥上游水股产生的动水垫效应的前提下,应尽量选择较小的射流入水间距,从而减小下游水股对床底的冲击压力。本研究可为水垫塘的优化设计、防护和坝身孔口的合理布局提供参考依据。展开更多
研究表孔采用上翘或下跌式、深孔采用下弯式布置所形成的表深孔上下差动出流,水股分层分散射流在水垫塘内的流动特征和各水股射流之间的干扰碰撞特性。选用非定常不可压缩流动的N-S方程和RNGk-ε紊流模型,采用VOF(Volume of Fluid)法,...研究表孔采用上翘或下跌式、深孔采用下弯式布置所形成的表深孔上下差动出流,水股分层分散射流在水垫塘内的流动特征和各水股射流之间的干扰碰撞特性。选用非定常不可压缩流动的N-S方程和RNGk-ε紊流模型,采用VOF(Volume of Fluid)法,结合溪洛渡双曲拱坝水垫塘,对不同间距的多层二元射流进入消力池后的水流结构进行了数值模拟。分析不同水股间距对水垫塘底板的冲击压力的影响以及与流场、速度场的关系。展开更多
文摘In this article, the transonic inviscid flow over a deformable airfoil with plunging motion is studied numerically. A finite volume method based on the Roe scheme developed in a generalized coordinate is used along with an arbitrary Lagrangian-Eulerian method and a dynamic mesh algorithm to track the instantaneous position of the airfoil. The effects of different governing parameters such as the phase angle, the deformation amplitude, the initial angle of attack, the flapping frequency, and the Mach number on the unsteady flow field and aerodynamic coefficients are investigated in detail. The results show that maneuverability of the airfoil under various flow conditions is improved by the deformation. In addition, as the oscillation frequency of the airfoil increases, its aerodynamic performance is significantly improved.
基金the United Research Foundation of the National Natural Science Foundation of China(Grant Nos.50539060and50709020)"973"Project of China(Grant No.2007CB714105)
文摘Based on the understanding of the mechanism of energy dissipation,a new type of plunge pool is presented with the advantages of high rate of energy dissipation,low impact pressure,and small close-to-bed velocity on the soleplate of the plunge pool.The first advantage owes to enlarged shearing energy dissipation areas in the plunge pool,while the other two are caused by the jet that enters in a nearly horizontal level to keep the soleplate from being scoured directly.All of the above arrangements make this new type of energy dissipator distinct from the underflow energy dissipation.Through experiments on the physical model,the authors found that the water flow maintained stable and submerged in horizontal direction when the flow was narrow in horizontal but thick in vertical direction.However,the wide flat nappe was ready to submerge or float as the downstream water level rised or dropped.The entire flow fields of multi-horizontal submerged jets into plunge pool were also numerically simulated.The numerical results of water surface curve,close-to-bed velocity and floor pressure agree well with the experimental data.The flow pattern in the plunge pool was analyzed after combining the laboratory data and numerical simulation.
文摘研究表深孔上下差动出流,水股分层分散射流在水垫塘的流动特征和各水股射流之间的干扰碰撞特性。选用非定常不可压缩流动的N-S方程和RNGk-ε紊流模型,采用VOF(Volume of Fluid)法结合溪洛渡双曲拱坝水垫塘对不同间距的多层二元射流进入水垫塘后的水流结构进行了数值模拟。通过对时间的迭代,计算和分析了水股间距对水垫塘恒定流场特性的影响,按多股射流入射水垫塘后的流动特征分为四类。给出了水股间距对水垫塘底板的冲击压力的影响规律以及与流场、速度场的关系,发现射流对水垫塘底板的冲击压力特点和速度场的分布特点相对应。研究认为:对于坝身泄洪为分层出流时,在射流入水间距能保证充分发挥上游水股产生的动水垫效应的前提下,应尽量选择较小的射流入水间距,从而减小下游水股对床底的冲击压力。本研究可为水垫塘的优化设计、防护和坝身孔口的合理布局提供参考依据。
文摘研究表孔采用上翘或下跌式、深孔采用下弯式布置所形成的表深孔上下差动出流,水股分层分散射流在水垫塘内的流动特征和各水股射流之间的干扰碰撞特性。选用非定常不可压缩流动的N-S方程和RNGk-ε紊流模型,采用VOF(Volume of Fluid)法,结合溪洛渡双曲拱坝水垫塘,对不同间距的多层二元射流进入消力池后的水流结构进行了数值模拟。分析不同水股间距对水垫塘底板的冲击压力的影响以及与流场、速度场的关系。
