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Acta Mechanica Sinica 2015年第4期31卷 570-580页

作者： laith k.abbas Qinbo Zhou Hossam Hendy Xiaoting Rui Institute of Launch Dynamics Nanjing University of Science and Technology

The analysis of natural vibration characteristics has become one of important steps of the manufacture and dynamic design in the aerospace industry. This paper presents a new scenario called virtual cutting in the context of the transfer matrix method of linear multibody systems closed- loop topology for computing the free vibration characteristics of elastically coupled flexible launch vehicle boosters. In this approach, the coupled system is idealized as a triple-beam system-like structure coupled by linear translational springs, where a non-uniform free-free Euler-Bemoulli beam is used. A large thrust-to-weight ratio leads to large axial accelera- tions that result in an axial inertia load distribution from nose to tail. Consequently, it causes the development of significant compressive forces along the length of the launch vehicle. Therefore, it is important to take into account this effect in the transverse vibration model. This scenario does not need the global dynamics equations of a system, and it has high computational efficiency and low memory requirements. The validity of the presented scenario is achieved through com- parison to other approaches published in the literature.

关键词： Transfer matrix method of linear multibodysystems Free vibration characteristics Coupled launchvehicle boosters

Suppression of vortex-induced vibrations of a flexible riser by adding helical strakes

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Journal of Hydrodynamics 2019年第3期31卷 622-631页

作者： Dong-yang Chen laith k. abbas Guo-ping Wang Xiao-ting Rui Wei-jie Lu School of Hydraulic Energy and Power Engineering Yangzhou University Yangzhou 225127 China Institute of La unch Dynamics Nanjing University of Science and Technology Nanjing 210094 China Nanjing Aerosun Corporation Nanjing 210000 China

3-D computational fluid dynamics/ computational structure dynamics (CFD/CSD) numerical two-way coupling simulations are conducted for a flexible rise in order to study the dynamic response performance of the riser with and without helical strakes exposed to the vortex-induced vibration (VIV). The VIV responses of a PVC riser without helical strakes are computed and compared with experimental data, to verify the accuracy of the present two-way coupling method. Subsequently, the dynamic behaviors of a short PVC riser with different kinds of helical strakes are studied. The vibration amplitudes along the riser, the trajectories of the riser's monitor point and the vortex shedding contours are obtained in a series of simulations. The helical strakes5 VIV suppression mechanisms are found involving the breaking of the vortex structures and the reduction of the vortex shedding frequency of the bare riser. Moreover, a good suppression effect can be achieved by attaching the helical strake structure with a reasonable geometrical configuration (such as the appropriate strake height, strake pitch, the number of starts and strake coverages) to the flexible riser. The effect is also diverse at different reduced velocity (Ur). The remarkable effect is found at Ur = l for the short riser, with about 97% reduction in the transverse vibration response.

关键词： Vortex-induced vibration (VIV) fluid structure interaction (FSI) Two-way coupling Helical strakes SST-SAS

Aero-thermo-elastic Numerical Calculation and Analysis of Spinning Rocket

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Transactions of Nanjing University of Aeronautics and Astronautics 2014年第6期31卷 681-687页

作者：陈东阳 laith k.abbas 芮筱亭 Marzocca Piergiovanni 王国平 Institute of Launch Dynamics Nanjing University of Science and Technology Department of Mechanical and Aerospace Engineering The Wallace H.Coulter School of EngineeringClarkson University

The application of computational fluid dynamics/computational solid method(CFD/CSM)on solving the aero-thermo-elastic problem of spinning rocket is ***,the aerodynamic coefficients of a rocket are calculated,and the results are compared with the available experimental data,which verified the accuracy of the CFD ***,analysis is carried using ANSYS Workbench multi-physics coupling platform,which includes fluid,thermal,and structural *** results show that spinning causes a significant effect on the deformations and ***,thermal stresses due to high temperature at the rocket warhead and tail edges have a dominated effect,even more than those produced by aerodynamic ***,this important outcome should be taken into consideration during the rocket design stages.

关键词： ANSYS Workbench numerical calculation thermal stress spinning

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柔性火箭弹气动力计算精度预测

哈尔滨工业大学学报 2016年第10期48卷 91-96页

作者：李敏娇 laith k.abbas 芮筱亭王国平南京理工大学发射动力学研究所南京210094

为验证小变形小攻角下基于准定常和线性理论进行柔性火箭弹气动力计算的合理性,采用计算流体力学(CFD)方法预测了某火箭弹的升力及阻力系数,并在此基础上与经验公式相结合,获得该火箭弹沿轴向的单位长度升力和阻力系数导数分布.应用多... 详细信息

为验证小变形小攻角下基于准定常和线性理论进行柔性火箭弹气动力计算的合理性,采用计算流体力学(CFD)方法预测了某火箭弹的升力及阻力系数,并在此基础上与经验公式相结合,获得该火箭弹沿轴向的单位长度升力和阻力系数导数分布.应用多体系统传递矩阵法计算了该火箭弹的固有频率和振型,在准定常及线性理论的假设条件下,结合已得到的气动力系数导数,计算了基于火箭弹一阶振型的两个弯曲模型在不同攻角下的单位长度气动力系数分布.与CFD计算结果进行对比,发现该火箭弹在实际飞行条件下,该计算方法精度较好,在远超于实际的大变形时、攻角较大的情况下在头部和弹身处仍具有一定精度,但尾部误差较大,总体精度降低.

关键词：多体系统传递矩阵法柔性火箭弹振动特性 CFD 气动力

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流场环境对柔性立管湿模态的影响

哈尔滨工程大学学报 2017年第10期38卷 1587-1594页

作者：陈东阳 laith k.abbas 王国平芮筱亭南京理工大学发射动力学研究所江苏南京210094

为了研究静水压力和瞬态流场载荷对三维柔性立管湿模态的影响,本文基于声-固耦合模型对考虑水介质、顶张力情况下的立管进行湿模态计算,并与理论计算结果以及实验数据对比,验证了该模型的准确性;采用不考虑流-固耦合的计算流体力学(comp... 详细信息

为了研究静水压力和瞬态流场载荷对三维柔性立管湿模态的影响,本文基于声-固耦合模型对考虑水介质、顶张力情况下的立管进行湿模态计算,并与理论计算结果以及实验数据对比,验证了该模型的准确性;采用不考虑流-固耦合的计算流体力学(computational fluid dynamics,CFD)方法和考虑流固双向耦合的计算流体力学/计算结构力学(computational fluid dynamics/computational structure dynamics,CFD/CSD)方法分别计算了立管的瞬态流场载荷,并与实验数据对比;将水深产生的静水压力和瞬态流场载荷分别加载到三维柔性立管表面进行静力学分析,计算其湿模态。计算结果表明:立管湿模态频率比干模态频率小很多,且随着顶张力增大而增大;静水压力和瞬态流场载荷都使得湿模态频率略微增加;静水压力和瞬态流场载荷对湿模态低阶振型影响较大,对高阶振型几乎没有影响。

关键词：湿模态声-固耦合模型涡激振动顶张力柔性立管瞬态流场载荷湍流模型干模态

Active Aerothermoelastic Control of Hypersonic Double-wedge Lifting Surface

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Chinese Journal of Aeronautics 2008年第1期21卷 8-18页

作者： laith k abbas 陈前 Piergiovanni Marzocca Gürdal Zafer Abdalla Mostafa 南京航空航天大学克拉克生大学代夫特科技大学

Designing re-entry space vehicles and high-speed aircraft requires special attention to the nonlinear thermoelastic and aerodynamic instability of their structural components. The thermal effects are important since temperature environment brings dramatic influences on the static and dynamic behaviors of flight structures in supersonic/hypersonic regimes and is likely to cause instability, catastrophic failure and oscillations resulting in structural failure due to fatigue. In order to understand the dynamic behaviors of these ＂hot＂ structures, a double-wedge lifting surface with combining freeplay and cubic structural nonlinearities in both plunging and pitching degrees-of-freedom operating in supersonic/hypersonic flight speed regimes has been analyzed. A third order piston theory aerodynamic is used to estimate the applied nonlinear unsteady aerodynamic loads. Also considered is the loss of torsional stiffness that may be incurred by lifting surfaces subject to axial stresses induced by aerodynamic heating. The aerodynamic heating effects are estimated based on the adiabatic wall temperature due to high speed airstreams. As a recently emerging technology, the active aerothermoelastic control is aimed at providing solutions to a large number of problems involving the aeronautical/aerospace flight vehicle structures. To prevent such damaging phenomena from occurring, an application of linear and nonlinear active control methods on both flutter boundary and post-flutter behavior has been fulfilled. In this paper, modeling issues as well as numerical simulation have been presented and pertinent conclusions outlined. It is evidenced that a serious loss of torsional stiffness may induce the dynamic instability; however active control can be used to expand the flutter boundary and convert unstable limit cycle oscillations （LCO） into the stable LCO and/or to shift the transition between these two states toward higher flight Mach numbers.

关键词： active control aerothermoelastic analysis freeplay hypersonic speed

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翼型非定常来流下复合运动动态失速仿真

哈尔滨工程大学学报 2019年第5期40卷 865-871页

作者：谢凯 laith k.abbas 陈东阳杨富锋芮筱亭南京理工大学发射动力学研究所江苏南京210094

针对直升机前飞时的动态失速问题,本文采用转捩修正的SST k-ω湍流模型和嵌套网格技术对雷诺数Re为3. 92×10~6时的直升机二维翼型SC1095进行数值仿真。以非定常来流条件下的纯俯仰运动为基础,对比分析了在耦合挥舞、摆振运动时,相位差... 详细信息

针对直升机前飞时的动态失速问题,本文采用转捩修正的SST k-ω湍流模型和嵌套网格技术对雷诺数Re为3. 92×10~6时的直升机二维翼型SC1095进行数值仿真。以非定常来流条件下的纯俯仰运动为基础,对比分析了在耦合挥舞、摆振运动时,相位差、振幅对动态失速的影响;比较挥舞、摆振二者运动对于动态失速角的作用大小。结果表明:固定振幅条件下,挥舞和摆振运动相位差的增加会使动态失速角提前,升力系数峰值提高;固定相位角条件下,挥舞和摆振运动振幅的增加会使动态失速角延迟,升力系数峰值减小。挥舞运动对于非定常来流下俯仰运动翼型动态失速角的影响要大于摆振运动。本文计算方法和研究结果为翼型多自由度耦合运动下的动态失速行为预测提供参考。

关键词：直升机旋翼翼型动态失速计算流体力学嵌套网格俯仰运动挥舞运动摆振运动

Non-linear Aerothermoelastic Modeling and Behavior of a Double-wedge Lifting Surface

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Journal of Shanghai Jiaotong university(Science) 2009年第5期14卷 620-625页

作者： laith k.abbas 芮筱亭 P.Marzocca Institute of Launch Dynamics School of Power EngineeringNanjing University of Sciences and Technology Clarkson University

The design of the re-entry space vehicles and high-speed aircraft structures requires special attention to the non-linear thermoelastic and aerodynamic *** thermal effects are important since temperature environment influences significantly the static and dynamic behaviors of flight structures in supersonic/hypersonic *** dynamic behavior of a double-wedge lifting surface with combined freeplay and cubic stiffening structural nonlinearities in both plunging and pitching degrees-of-freedom(DOF) operating in supersonic/hypersonic flight speed regimes has been *** addition a third order piston theory aerodynamics(PTA) is used to evaluate the non-linear unsteady aerodynamic loads applied to the wing *** of torsional stiffness that may be incurred by lifting surfaces subjected to axial stresses induced by aerodynamic heating is also *** aerodynamic heating effect is estimated based on the adiabatic wall temperature due to high speed *** is demonstrated that serious losses of torsional stiffness may occur in such lifting surfaces;the influence of various parameters such as flight condition,thickness ratio,freeplays and pitching stiffness nonlinearity are discussed.

关键词： non-linear aerothermoelastic analysis thermal loading freeplay hypersonic speed

结构误差对旋转稳定弹丸气动特性影响的数值模拟

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空气动力学学报 2014年第5期32卷 705-711页

作者：陈东阳 laith k.abbas 芮筱亭王国平南京理工大学发射动力学研究所江苏南京210094

基于剪切应力传输(SST)k-ω湍流模型,对考虑结构误差情况下的弹箭模型进行数值模拟计算。首先采用CFD和工程经验公式相结合的方法,得到了不同马赫数、不同转速情况下无结构误差模型的多种气动特性参数。通过与实验数据对比,阻力、法向... 详细信息

基于剪切应力传输(SST)k-ω湍流模型,对考虑结构误差情况下的弹箭模型进行数值模拟计算。首先采用CFD和工程经验公式相结合的方法,得到了不同马赫数、不同转速情况下无结构误差模型的多种气动特性参数。通过与实验数据对比,阻力、法向力、俯仰力矩、压心位置误差在10%以内,验证了该方法的可行性和准确性。然后,建立了考虑结构误差即质量分布不对称、弹体不同轴和无结构误差模型,并分别进行了气动特性模拟计算。结果表明,质量偏心对滚转阻尼力矩系数、马格努斯力矩系数影响很大;弹体不同轴对法向力系数导数、俯仰力矩系数导数、马格努斯力矩系数导数和压心位置都产生很大影响。结构误差使模型的多种气动特性参数产生很大变化,将影响其飞行弹道和稳定性。

关键词：结构误差湍流模型计算流体力学旋转

基于多体系统传递矩阵法和遗传算法的一种物理参数识别方法

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振动工程学报 2011年第6期24卷 607-612页

作者：马蕾芮筱亭杨富锋 laith k abbas 文兵南京理工大学发射动力学研究所江苏南京210094

将多体系统传递矩阵法与遗传优化算法相结合,形成了一种新的基于多体系统传递矩阵法和遗传算法的物理参数识别方法(MS-TMM&GA)。应用多体系统传递矩阵法进行动力学建模以及固有振动特性分析。将参数识别问题转化为优化问题,结合遗传算法... 详细信息

将多体系统传递矩阵法与遗传优化算法相结合,形成了一种新的基于多体系统传递矩阵法和遗传算法的物理参数识别方法(MS-TMM&GA)。应用多体系统传递矩阵法进行动力学建模以及固有振动特性分析。将参数识别问题转化为优化问题,结合遗传算法,对由系统固有频率和增广特征矢量构造的目标函数全局最小值优化求解。给出了通过系统模态参数识别物理参数的计算步骤以及流程图。通过两个数值算例,表明了该方法的可行性及有效性。该方法对多体系统传递矩阵法和遗传算法进行了结合与拓展,无需建立复杂多体系统的总体动力学方程,涉及矩阵阶次低,即可快速获得高精度的优化计算结果。

关键词：多体系统传递矩阵法(MS-TMM) 物理参数识别遗传算法(GA) 固有振动特性