排序方式: 共有33条查询结果,搜索用时 31 毫秒
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运用CAD/CAE集成设计技术对某飞机承力密封框进行了设计:建立了CAD模型和CAE模型;根据承力密封框的使用环境和设计要求,确定了对其进行刚度和强度分析时所需的各种主要参数;应用CAE系统软件计算承力密封框的刚度和强度,并分析了计算结果。 相似文献
2.
细长体绕流tertiary涡的形成与非对称过程 总被引:3,自引:0,他引:3
为探讨现代飞行器非对称流动中主涡的形成机理,利用染色线显示和荧光诱导激光片光技术,在北京航空航天大学1.2m水洞对细长体绕流过程进行了实验研究。结果表明,亚临界Re和大迎角零侧滑绕流时,细长体流场呈现复杂的非对称多涡流动现象。随着主涡的生成和发展,在模型背风侧再分离区诱导出一些次生结构,tertiary涡就是其中一种。沿着轴向,主涡发展成熟并依次脱落形成脱体涡,从主涡脱落点也依次产生新生主涡。其中,第1个新生涡由tertiary涡发展而来,而第2个和第3个新生涡则主要由分离剪切层卷绕生成。该文提出了tertiary涡演化为新生主涡的观点。 相似文献
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The study of rotor–fuselage interactional aerodynamics is central to the design and performance analysis of helicopters. However, regardless of its significance, rotor–fuselage aerodynamics has so far been addressed by very few authors. This is mainly due to the difficulties associated with both experimental and computational techniques when such complex configurations, rich in flow physics, are considered. In view of the above, the objective of this study is to develop computational tools suitable for rotor–fuselage engineering analysis based on computational fluid dynamics (CFD). To account for the relative motion between the fuselage and the rotor blades, the concept of sliding meshes is introduced. A sliding surface forms a boundary between a CFD mesh around the fuselage and a rotor‐fixed CFD mesh which rotates to account for the movement of the rotor. The sliding surface allows communication between meshes. Meshes adjacent to the sliding surface do not necessarily have matching nodes or even the same number of cell faces. This poses a problem of interpolation, which should not introduce numerical artefacts in the solution and should have minimal effects on the overall solution quality. As an additional objective, the employed sliding mesh algorithms should have small CPU overhead. The sliding mesh methods developed for this work are demonstrated for both simple and complex cases with emphasis placed on the presentation of the inner workings of the developed algorithms. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
4.
The paper presents a nonlinear model describing vibration of the landing gear relative to the fuselage. The model is intended
to analyze the dynamic stability of nonswiveling main-gear wheels. The model is used to show that the lateral component of
the fuselage speed has a significant effect on the critical shimmy speed
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Translated from Prikladnaya Mekhanika, Vol. 42, No. 9, pp. 134–142, September 2006. 相似文献
5.
The resistance to the blood cells at the entrance to capillaries and membrane pores contributes considerably to the peripheral resistance in the blood circulation. This paper proposes, for the first time, a simplified mechanical model in an attempt to treat the axisymmetric motion of a cell sliding into a circular pore. In this model, the shape of the cell is taken as given according to the microvideograph and the cell membrane is assumed to slide over its surface. The lubrication theory is applied to the thin layers of plasma between the membrane and the pore wall, yielding the pressure and shear stress distributions over the membrane as well as the resultant drag exerted on the cell. Our computations have simulated the process of the cell entering the pore, which is in qualitative agreement with the microvideographic observations.The Project Supported by National Natural Science Foundation of China.The authors wish to express their thanks to Professor S. Weinbaum of The City University of New York for his enlightening suggestions on the mechanical model of this problem during his visit to Peking University. The authors are also grateful to Professor Li Gui-shan of Institute of blood. The Chinese Academy of Medical Sciences, for providing the relevant microvideographes. 相似文献
6.
考虑机翼机身弹性的起落架着陆性能分析 总被引:1,自引:0,他引:1
通过建立飞机着陆弹性机体等效多质量模型,导出了着陆系统的微分方程,基于ADAMS/Aircraft 软件建立了含弹性机体的全机着陆虚通拟样机,仿真出飞机着陆时的动态响应。着陆仿真分析结果与初始设计值的一致性较好,误差在5%以内,为大飞机起落架设计过程中考虑机体弹性的影响提供了有益的参考。 相似文献
7.
The paper details the stress characteristics in eccentrically loaded aircraft spliced joints. It is shown that the hoop stress (σθθ) around each rivet is characterized by two peak values located at θ = (0°, 90°). The magnitude of (σθθ) is then reduced to a minimum value between these two peaks. A sharp increase in the axial stress component (σxx) along the vertical splice lines occurs in the vicinity of the rivet centerlines followed by a rapid decrease in the areas between the rivets. It is shown that stresses along the first interior rivet row is the most critical. The axial stress (σxx) profile along horizontal rivet lines has a “sinusoidal” pattern. It is observed that the transverse stress profile (σyy), along the horizontal lines, has different peak and minimum values between the rivets. The magnitude of the peak/minimum values depends upon the line location within the splice region. It is also shown the bending stress component varies significantly and must be accounted for the analysis of the eccentric aircraft joints. Experimental comparisons are made along several lines in the splice region. The numerical model is utilized for analysis of a full frame-bay/splice of aircraft fuselage. The paper provides valuable information that can be utilized by practicing engineers for analysis and design of joints with large number of rivets. 相似文献
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Summary The aeroelastic response analysis of a coupled rotor/fuselage system is approached by iterative solution of the blade aeroelastic
response in the non-inertial reference frame fixed on the hub, and the periodic response of the fuselage in the inertial reference
frame. A model of the coupled system hinged with the flap and lag hinges, the pitching bearing which may not coincide with
the hinges, and the sweeping-blade configuration is established. The moderate-deflection beam theory and the two-dimensional
quasi-steady aerodynamic model are employed to model the aeroelastic blade, all the kinetic and inertial factors are taken
into account in a unified manner. A five-nodes, 15-DOFs pre-twisted nonuniform beam element is developed for the discretization
of the blade, three rigid-body-motion DOFs are introduced for the motion of the hinges and the bearing. The Hamilton's principle
is employed to evaluate the equation of motion of the blade. The derived nonlinear ordinary differential equations with time-dependent
periodic coefficients are solved by a modified quasi-linearization method, which is developed for the higher DOF periodic
system. The resulting periodic forces and moments exerted on the fuselage by all the blades are evaluated every time, when
the converged nonlinear periodic response of the blade is obtained under the consideration of the equilibrium of the blades.
The fuselage structure is simplified to be a beam structure, the governing equation is established in the inertial reference
frame and a two-nodes beam element is used to discretize the flexible fuselage. The periodic response of the fuselage is solved
by a simple shooting method. The iteration of the rotor/fuselage response is continued, until the aeroelastic responses of
the blade and the fuselage converge simultaneously. Both the hovering and the forward flight states can be considered. The
results of a computed numerical example by the developed program are presented to verify in practice the economy of the modeling
as well as the reliability and efficiency of the corresponding solving methods.
Received 4 May 1998; accepted 11 August 1998 相似文献