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《力学学报》2013,(6)
利用等离子体激励器发展了新型的环量增升技术,并对二维NACA0012翼型绕流实施控制.由于NACA0012翼型为尖后缘构型,环量增升装置由2个非对称型介质阻挡放电等离子体激励器构成.一个等离子体激励器贴附于翼型吸力面靠近后缘处,其诱导的壁面射流沿来流方向指向下游;另一个等离子体激励器贴附于翼型压力面靠近后缘处,其诱导的壁面射流与来流方向相反指向上游.在风洞中通过时间解析二维PIV系统对翼型绕流流场进行了测量,基于翼型弦长的雷诺数Re=20000.结果表明在等离子体激励器的控制下,翼型压力面靠近后缘处可以形成一个定常回流区,从而起到虚拟气动外形的作用,因此翼型吸力面的流场得到加速,压力面的流场得到减速,使得翼型压力面的吸力以及压力面的压力都得到增加,进而增加了翼型的环量.风洞天平测力实验进一步验证了该环量增升技术的有效性.在整个攻角范围内,施加控制的翼型的升力系数相比没有控制的工况有明显的提高. 相似文献
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利用等离子体激励器发展了新型的环量增升技术,并对二维NACA0012翼型绕流实施控制。由于NACA0012翼型为尖后缘构型,环量增升装置由2个非对称型介质阻挡放电等离子体激励器构成。一个等离子体激励器贴附于翼型吸力面靠近后缘处,其诱导的壁面射流沿来流方向指向下游;另一个等离子体激励器贴附于翼型压力面靠近后缘处,其诱导的壁面射流与来流方向相反指向上游。在风洞中通过时间解析二维PIV系统对翼型绕流流场进行了测量,基于翼型弦长的雷诺数Re=20 000。结果表明在等离子体激励器的控制下,翼型压力面靠近后缘处可以形成一个定常回流区,从而起到虚拟气动外形的作用,因此翼型吸力面的流场得到加速,压力面的流场得到减速,使得翼型压力面的吸力以及压力面的压力都得到增加,进而增加了翼型的环量。风洞天平测力实验进一步验证了该环量增升技术的有效性。在整个攻角范围内,施加控制的翼型的升力系数相比没有控制的工况有明显的提高。 相似文献
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利用有限体积法实现了基于非正交同位网格的SIMPLE算法。基于熵分析方法,采用涡粘性模型求解湍流熵产方程,系统研究了湍流模型对二维翼型绕流流场熵产率的影响。通过计算NACA0012翼型在来流雷诺数为2.88×106时,0°攻角~16.5°攻角范围内的翼型表面压力系数分布和升阻力特性,验证了算法及程序的正确性。结果表明,选择不同湍流模型时,翼型流场熵产的计算结果存在差异,湍流耗散是引起流场熵产的主要原因;翼型流场的熵产主要发生在翼型前缘区、壁面边界层和翼型尾流区域,流场熵产率与翼型阻力系数线性相关;当产生分离涡时,粘性耗散引起的熵产下降。 相似文献
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翼型绕流的电磁力控制 总被引:3,自引:0,他引:3
将表面包覆电磁激活板的翼型,按一定的攻角,置于流动的弱电介质溶液中,电磁激活板可产生作用于流体的切向电磁力(Lorentz力),从而改变流体边界层的结构. 在转动水槽中,对翼型绕流及电磁力控制下的绕流形态进行了实验研究. 结果表明,未加电磁力时,前缘涡的脱落点是不确定的,与流场具体条件有关,而后缘涡仅在尖角处脱落. 前缘涡与后缘涡相互影响,并周期性的脱体,在尾部形成涡街. 施加电磁力后,当力的方向与流动方向相同时,可以在一定程度上抑制分离,消除涡街,其效果与减小攻角类似. 加反向电磁力时,则相当于加大攻角,在翼型体的背风面形成涡街. 相似文献
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利用有限体积法实现了基于非正交同位网格的SIMPLE算法。基于熵分析方法,采用涡粘性模型求解湍流熵产方程,系统研究了湍流模型对二维翼型绕流流场熵产率的影响。通过计算NACA0012翼型在来流雷诺数为2.88×106时,0°攻角~16.5°攻角范围内的翼型表面压力系数分布和升阻力特性,验证了算法及程序的正确性。结果表明,选择不同湍流模型时,翼型流场熵产的计算结果存在差异,湍流耗散是引起流场熵产的主要原因;翼型流场的熵产主要发生在翼型前缘区、壁面边界层和翼型尾流区域,流场熵产率与翼型阻力系数线性相关;当产生分离涡时,粘性耗散引起的熵产下降。 相似文献
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利用同位非结构化网格上的压力加权修正算法 ,对翼型湍流绕流进行了数值分析。详细地给出了一孤立翼型在不同攻角下的分离流结构及翼型表面压力分布 ,为了显示非结构化网格方法在求解多连通流动区域的优越性 ,对双翼型绕流进行了数值计算。在数值分析中 ,对阵面推进法进行改进来生成三角形网格 ,采用有限控制体方法直接在物理空间中的非结构化网格单元上离散 Navier- Stokes方程及 k- ε方程 ,形成的代数方程组通过预条件矩阵共轭梯度平方法求解。计算结果表明 :当流动为附着流时 ,计算结果与实验值吻合程度令人相当满意 ;而在分离区内 ,计算结果与实验值存在一定的误差 ,需对分离区内的湍流模型做进一步的改进。 相似文献
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对在低雷诺数下局部弹性翼型绕流中, 局部弹性导致的自激振动所产生的复杂非定常流动分离现象和描述方法进行了分析. 采用ALE-CBS方法数值模拟了具有可动边界的绕流流场问题, 同时采用Galerkin方法求解局部弹性结构的控制方程. 着重研究了翼型的局部弹性对流动分离和翼型性能的影响, 并分别从Eulerian和Lagrangian的角度分析了局部弹性结构导致的不同非定常分离现象, 其中Lagrangian角度可以方便地揭示出局部弹性翼型大幅度提高升力的机理和流动中的能量迁移. 结果表明翼型的局部弹性对非定常分离和分离泡的演化过程有着明显的影响, 可以使得流体质点由主流获取动量实现再附, 并且在一定的攻角下可以将固定分离转变为移动分离, 从而明显地提高了翼型的升力. 相似文献
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以S809翼型为研究对象,用CFD数值模拟计算的方法研究了在失速条件下,风力机翼型上下表面同时开缝的被动控制策略对翼型空气动力学特性的影响。采用基于速度耦合的SIMPLEC算法进行数值模拟,将四种常用的湍流模型(Spalart-Allmaras、k-e、k-w、k-w-SST)在12°和24°攻角下的计算结果和实验数据对比,得出了最优于翼型计算的湍流模型为k-w-SST。分析了缝隙位置、宽度和斜率对翼型气动性能的影响。结果表明:当开缝位置位于分离点附近时,翼型气动性能最优;当缝隙宽度为弦长的2%时,翼型气动性能最优;当缝隙和弦线的夹角为75°时,翼型气动性能最优,且在攻角超过24°时开缝对翼型的气动性能有不利影响。 相似文献
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The limit cycle oscillation (LCO) behaviors of an aeroelastic airfoil with free-play for different Mach numbers are studied. Euler equations are adopted to obtain the unsteady aerodynamic forces. Aerodynamic and structural describing functions are employed to deal with aerodynamic and structural nonlinearities, respectively. Then the flutter speed and flutter frequency are obtained by V-g method. The LCO solutions for the aeroelastic airfoil obtained by using dynamically linear aerodynamics agree well with those obtained directly by using nonlinear aerodynamics. Subsequently, the dynamically linear aerodynamics is assumed, and results show that the LCOs behave variously in different Mach number ranges. A subcritical bifurcation, consisting of both stable and unstable branches, is firstly observed in subsonic and high subsonic regime. Then in a narrow Mach number range, the unstable LCOs with small amplitudes turn to be stable ones dominated by the single degree of freedom flutter. Meanwhile, these LCOs can persist down to very low flutter speeds. When the Mach number is increased further, the stable branch turns back to be unstable. To address the reason of the stability variation for different Mach numbers at small amplitude LCOs, we find that the Mach number freeze phenomenon provides a physics-based explanation and the phase reversal of the aerodynamic forces will trigger the single degree of freedom flutter in the narrow Mach number range between the low and high Mach numbers of the chimney region. The high Mach number can be predicted by the freeze Mach number, and the low one can be estimated by the Mach number at which the aerodynamic center of the airfoil lies near its elastic axis. Influence of angle of attack and viscous effects on the LCO behavior is also discussed. 相似文献
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This paper presents a mathematical study on the subsonic aerodynamics acting on an airfoil with a cubic stiffness. One portion of aerodynamics is assumed as and replaced by an equivalent damping. Using the harmonic balance method, an equivalent system is deduced and studied by a numerical integration method. Numerical examples show the validity and feasibility of the proposed mathematical treatment of the aerodynamics. It reveals that the unsteady aerodynamics acting on the airfoil can not only affect the pitch stiffness but also result in additional damping. 相似文献
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“FLUID ROLLER BEARING” EFFECT AND FLOW CONTROL 总被引:1,自引:0,他引:1
Owing to the rapid development of smart materials, flow control by travelling waves (TW) produced on flexible skin is becoming a very promising new area of research. One of the most revolutionary concepts of using TW technique is to trap a row of controllable vortices over the body surface, which plays a role of “fluid roller bearing” (FRB) between the external flow and the solid wall. The FRB can replace the conventional boundary layer and hence remove the latter‘‘s various unfavorable effects. This paper reports our preliminary numerical study of the FRB effect on flow over several typical walls, especially an airfoil with FRB at the stall angle of attack, which has never been considered before. Significant improvement of aerodynamic performance on the FRB-airfoil is observed, which strongly suggests that the FRB effect may open a brand new avenue to the 21th-Century aerodynamics. 相似文献
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等速上仰翼型动态失速现象研究 总被引:9,自引:0,他引:9
翼型大迎角绕流的静态失速将造成升力突降和气动性能急剧恶化,但利用非定常运动所产生
的动态失速效应,可以大大地延缓气流分离和失速现象的发生. 采用Rogers发
展的双时间步Roe格式,求解拟压缩性修正不可压N-S方程. 数值模拟了低雷诺数
($Re=4.8 \times 10^{4}$)条件下NACA0015翼型作等速上仰($\alpha
=0^{\circ} \sim 60^{\circ}$)的动态失速过程,同Walker的试验结果比
较,验证了计算结果的正确性. 研究了该过程中主涡、二次涡和三次涡的发展,升
力系数随攻角变化,以及不同上仰速度对动态失速效应所造成的影响. 相似文献
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S. M. Aulchenko V. P. Zamuraev A. P. Kalinina 《Journal of Applied Mechanics and Technical Physics》2008,49(6):957-961
The possibility of controlling the aerodynamic characteristics of airfoils in transonic flight regimes by means of one-sided
pulsed-periodic energy supply is studied. Based on the numerical solution of two-dimensional unsteady gas-dynamic equations,
the change in the flow structure in the vicinity of a symmetric airfoil at different angles of attack and the aerodynamic
characteristics of the airfoil as functions of the amount of energy supplied asymmetrically (with respect to the airfoil)
are determined. The results obtained are compared with the data calculated for the flow past the airfoil at different angles
of attack without energy supply. It is found that a given lift force can be obtained with the use of energy supply at a much
better lift-to-drag ratio of the airfoil, as compared to the case of the flow past the airfoil at an angle of attack. The
moment characteristics of the airfoil are found.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 49, No. 6, pp. 82–87, November–December, 2008. 相似文献
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S. M. Aulchenko V. P. Zamuraev A. P. Kalinina 《Journal of Applied Mechanics and Technical Physics》2007,48(6):834-839
The possibility of controlling the aerodynamic characteristics of airfoils in transonic flight regimes by means of local pulsed
periodic energy supply is considered. The numerical solution of two-dimensional unsteady equations of gas dynamics allowed
determining the changes in the flow structure near a symmetric airfoil and its aerodynamic characteristics depending on the
magnitude of energy in the case of its asymmetric (with respect to the airfoil) supply. The results obtained are compared
with the calculated data for the flow around the airfoil at different angles of attack without energy supply. With the use
of energy supply, a prescribed lift force can be obtained with a substantially lower wave drag of the airfoil, as compared
with the flow around the airfoil at an angle of attack.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 48, No. 6, pp. 70–76, November–December, 2007. 相似文献
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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. 相似文献
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Research on the hysteresis properties of unsteady aerodynamics about the oscillating wings 总被引:1,自引:0,他引:1
高正红 《应用数学和力学(英文版)》1999,20(8):895-907
IntroductionAstherequirementofhighperformanceandmaneuverability,thenextgenerationofthefighteraircraftisbeingdesignedtoflyandb... 相似文献