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带气弹稳定性约束的复合材料浆叶减振优化设计 总被引:1,自引:0,他引:1
研究以降低直升机旋翼激振力为目标的复合材料桨叶结构动力学减振优化设计 ,分析了桨叶结构特性及桨尖后掠角等参数对N次 /转旋翼桨毂振动载荷的影响。在建立的桨叶二维结构特性有限元分析方程中 ,计入了桨叶剖面翘曲变形的影响 ,并利用哈密尔顿原理推导了旋翼桨叶的一维非线性运动微分方程。以桨毂交变载荷为目标函数 ,直接以复合材料桨叶典型剖面构造节点数据、铺层设计参数和桨尖后掠角等为设计变量 ,引入桨叶挥舞惯量、固有频率和气弹稳定性约束 ,进行旋翼的动力学优化设计 ,并结合 3片桨叶旋翼的设计进行了算例分析 ,优化结果使 3次/转的桨毂载荷降低了 2 4 .9%~ 33%。 相似文献
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多片后缘小翼对直升机旋翼桨叶动态失速及桨毂振动载荷的控制 总被引:7,自引:2,他引:5
减缓直升机后行桨叶动态失速发生、降低直升机桨毂振动载荷是提高直升机飞行速度、改进直升机飞行性能的重要途径。本文研究了直升机在高速高载情况下利用多片受控的桨叶后缘小翼对直升机的后行桨叶动态失速和桨毂振动载荷同时进行控制的有效方法。建立了弹性桨叶和后缘刚性小翼的结构动力学模型。桨叶剖面气动载荷采用Leishman-Beddoes 二维非定常动态失速模型计算,后缘小翼剖面气动载荷采用Hariharan-Leishman二维亚声速非定常气动模型计算。采用伽辽金和数值积分相结合的方法求解旋翼系统的气弹响应。建立了有效的多片后缘小翼控制策略和控制方法,分析了3片后缘小翼的运动规律及对后行桨叶动态失速和桨毂振动载荷的控制效果,结果表明利用多片小翼的运动是控制桨叶动态失速和桨毂振动载荷的有效方法。 相似文献
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颗粒阻尼对直升机旋翼桨叶减振效果的试验 总被引:6,自引:1,他引:5
为探索直升机减振技术的新方法,研究颗粒阻尼技术在直升机旋翼桨叶减振中的应用,设计了直升机旋翼桨叶模型及其相应的颗粒阻尼器形式,利用试验方法研究了颗粒阻尼对非旋转及旋转桨叶模型的阻尼减振效果。试验结果表明:颗粒阻尼可以有效提高非旋转桨叶模型的前3阶阻尼水平,尤其可使桨叶第3阶模态阻尼比提高一个数量级甚至更多;在较低的转速范围内,颗粒阻尼还可以克服离心力作用,使旋转桨叶模型的挥舞和摆振加速度响应水平均得到有效削减,充分表明了颗粒阻尼作为一种振动控制手段应用于直升机旋翼桨叶的可行性。 相似文献
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依据大速度前飞状态桨叶气动环境,通过对桨叶动力响应、翼型气动力、流场尾迹分布和桨根力等四个方面的分析,建立桨毂振动载荷预计模型。基于Leishman—Beddoes的附着流模型和动态失速模型计算翼型气动力,桨叶运动考虑刚性挥舞模态和弹性挥舞模态,诱导速度采用动力人流理论和Pite—He广义动态尾迹理论。利用状态空间法对方程进行离散化处理。以某型直升机为例。通过几种不同模型的计算,表明流场尾迹分布和桨叶运动变形对桨毂振动载荷预计有较大影响。 相似文献
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随着新构型直升机技术的发展,对直升机桨叶有限元仿真技术的要求也越来越高。参数化建模仿真方法能够降低有限元法仿真技术的使用难度,对桨叶快速化、精细化设计具有重要意义。本文基于ABAQUS二次开发方法构建了一种适用于直升机桨叶根部段的快速建模方法,在有限元建模过程中参数化建立材料属性和接触属性,完成直升机复合材料桨叶根部段的快速化仿真分析。利用该方法对某直升机桨根进行应力计算,与常规建模方法相比,快速建模方法有效提高了建模效率,保证了仿真结果的一致性。快速建模方法仿真结果与常规建模方法仿真结果相比应变误差不超过1%,快速建模方法与试验结果相比应变误差不超过10%,常规建模与试验结果应变误差不超过91%,验证了该方法的可靠性。 相似文献
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旋翼桨叶气动外形设计 总被引:1,自引:0,他引:1
旋翼桨叶气动外形设计的目的主要是使旋翼的气动特性满足直升机的设计和使用要求,本文针对直升机旋翼桨叶气动外形设计中的有关问题,介绍了桨叶气动外形设计的设计方法,设计参数主要包括桨叶的弦长、扭转角、翼型选择和配置以及桨尖形状,并以某型直升机旋翼桨叶为例,介绍了旋翼桨叶气动外形的设计。 相似文献
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为开展气流激励下叶片振动响应分析方法研究,建立了气动激振力预估方法,采用非线性谐波法对叶排进行三维非定常流动分析,获得叶片表面的脉动压力,编制流固转换程序,计算叶片所受的气动激振力。建立了叶片气动阻尼分析方法,基于能量法和弱耦合分析法,对叶片与流场进行流固弱耦合分析,将气动力对运动的叶片所做的气动负功等效为黏滞阻尼力所做的功,求得转子叶片的模态气动阻尼比。建立了叶片在气流激励下的振动响应分析方法,基于气动激振力和叶片模态气动阻尼比,采用模态叠加法分析叶片振动响应。使用该方法,针对发动机中1.5级压气机转、静子叶排模型,计算了转子叶片在真实流场中的气动激振力、前8阶模态气动阻尼比以及在气动激振力与气动阻尼共同作用下转子叶片的振动响应,振动应力达到100 MPa。 相似文献
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《中国航空学报》2020,33(6):1642-1660
Substantial unbalance may be caused by fan blade off during the operation period of gas turbine engines, and related dynamic problems are very critical to the safety design of rotor system in aero-engine. This article aims to understand lateral-torsional coupled vibration of the rotor system with substantial unbalance. The governing equation of a modified unbalanced rotor system is established based on Lagrangian approach. Then, a mathematical analytical method is proposed in which a linear approximation is derived and the Floquet theory and Hill’s method are incorporated, from which the modal characteristics of the unbalanced rotor are obtained. The modal characteristics of the unbalanced rotor system are revealed comprehensively for the first time. Furthermore, the relation between the modes and responses of the unbalanced rotor is discussed in detail. The results show that the lateral vibration and torsional vibration of the unbalanced rotor are coupled through the inertial terms in the governing equations. Due to the coupling, veering and lock-in phenomena occur between the frequencies of the forward whirl mode and the torsional mode. Furthermore, lock-in can lead to a kind of principal instability. With regard to the response of the unbalanced rotor, both natural vibration components and enforced vibration components appear in the lateral response, while only natural vibration components appear during torsional vibration. Moreover, natural vibration components play a crucial role in the response within the principal instability region and cause divergence of the vibration amplitudes in the lateral and torsional directions. 相似文献
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《中国航空学报》2023,36(1):178-190
This study numerically investigates the aeromechanic behavior of a transonic fan model with a flat tip-leading-edge on the NASA rotor 67 test case. Single-passage unsteady calculations at a near stall operating point of 82% design speed show that the dominant frequencies of mass flow were not the harmonics of the rotor rotational frequency. A full-annulus fluid–structure interaction analysis was subsequently carried out to examine the unsteady flows and their interactions with blade vibrations. The results show that the modal displacement of the backward traveling seventh nodal diameter of the second torsion mode grew exponentially, which reveals that the blade vibration was non-synchronous. The vibration pattern indicates that the aerodynamic mode was resonant with the structural vibration mode. Around the rotor tip, the circumferential vortical propagation induced by interactions among the main flow, tip leakage flow, and tip clearance vortex was the source of aerodynamic excitation. To clarify the mechanism of the non-synchronous vibration, the coupling between aerodynamic disturbance and structural response, i.e., aliasing, was summarized. The frequency spectra of the fluctuating pressure show that an aerodynamic Backward Traveling Wave (BTW) was co-aliased to a structural BTW due to the propagation of the circumferential vortex. The correlation between the frequency and free convective speed of the aerodynamic disturbance determined the directions of aliasing. 相似文献