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8篇 您的检索式:作者名="Laith K.Abbas"
    题名 作者 年代 出处 被引量
1翼型非定常来流下复合运动动态失速仿真显示文摘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。谢凯 Laith K.Abbas 陈东阳 杨富锋 芮筱亭 2019哈尔滨工程大学学报2019,40,5:10
2流场环境对柔性立管湿模态的影响显示文摘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。陈东阳 Laith K.Abbas 王国平 芮筱亭 2017哈尔滨工程大学学报2017,38,10:6
3结构误差对旋转稳定弹丸气动特性影响的数值模拟显示文摘基于剪切应力传输(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。陈东阳 Laith K.Abbas 芮筱亭 王国平 2014空气动力学学报2014,32,5:6
4旋转弹箭气动导数与气动热仿真计算显示文摘研究弹箭气动特性优化问题,基于剪切应力传输(SST)k-ω湍流模型,分别对M910弹丸和旋转弹模型F4进行数值仿真。计算采用CFD和工程经验公式相结合的方法,得到了光弹M910和翼身组合体F4在不同攻角,不同旋转速度,不同马赫数下的气动导数分布。通过与实验数据比较分析,阻力系数,法向力系数,俯仰力矩系数导数,滚转阻尼系数误差均在工程误差范围内,验证了本文计算方法的准确性。同时,数值仿真得到旋转弹体绝热壁面温度分布云图和不同旋转速度、不同攻角的弹箭迎风面中心线上温度分布数据图。计算分析为旋转弹箭气动热弹性仿真提供有价值参考。陈东阳 Laith K.Abbas 芮筱亭 2014计算机仿真2014,31,5:5
5Transfer matrix method for determination of the natural vibration characteristics of elastically coupled launch vehicle boosters显示文摘The analysis of natural vibration characteristics has become one of important steps of the manufacture and dynamicdesignintheaerospaceindustry.Thispaperpresents a new scenario called virtual cutting in the context of the transfer matrix method of linear multibody systems closedlooptopologyforcomputingthefreevibrationcharacteristics of elastically coupled fl xible 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–Bernoulli beam is used.A large thrust-to-weight ratio leads to large axial accelerations that result in an axial inertia load distribution from nose to tail. Consequently, it causes the development of significan 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 efficien y and low memory requirements. The validity of the presented scenario is achieved through comparison to other approaches published in the literature.Laith K.Abbas Qinbo Zhou Hossam Hendy Xiaoting Rui 2015Acta Mechanica Sinica2015,31,4:3
6柔性火箭弹气动力计算精度预测显示文摘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.李敏娇 Laith K.Abbas 芮筱亭 王国平 2016哈尔滨工业大学学报2016,48,10:1
7Aero-thermo-elastic Numerical Calculation and Analysis of Spinning Rocket显示文摘The application of computational fluid dynamics/computational solid method(CFD/CSM)on solving the aero-thermo-elastic problem of spinning rocket is introduced.Firstly,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 output.Then,analysis is carried using ANSYS Workbench multi-physics coupling platform,which includes fluid,thermal,and structural solvers.The results show that spinning causes a significant effect on the deformations and stresses.Furthermore,thermal stresses due to high temperature at the rocket warhead and tail edges have a dominated effect,even more than those produced by aerodynamic forces.Consequently,this important outcome should be taken into consideration during the rocket design stages.陈东阳 Laith K.Abbas 芮筱亭 Marzocca Piergiovanni 王国平 2014Transactions of Nanjing University of Aeronautics and Astronautics2014,31,6:0
8Non-linear Aerothermoelastic Modeling and Behavior of a Double-wedge Lifting Surface显示文摘The design of the re-entry space vehicles and high-speed aircraft structures requires special attention to the non-linear thermoelastic and aerodynamic instabilities.The thermal effects are important since temperature environment influences significantly the static and dynamic behaviors of flight structures in supersonic/hypersonic regimes.The 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 analyzed.In addition a third order piston theory aerodynamics(PTA) is used to evaluate the non-linear unsteady aerodynamic loads applied to the wing section.Loss of torsional stiffness that may be incurred by lifting surfaces subjected to axial stresses induced by aerodynamic heating is also considered.The aerodynamic heating effect is estimated based on the adiabatic wall temperature due to high speed airstreams.It 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.Laith K.Abbas 芮筱亭 P.Marzocca 2009Journal of Shanghai Jiaotong university(Science)2009,14,5:0
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