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101.
E. V. Ermanyuk N. V. Gavrilov 《Journal of Applied Mechanics and Technical Physics》2005,46(6):800-806
The hydrodynamic loads due to the interaction of a small-amplitude internal solitary wave with a submerged circular cylinder
in a two-layer system of miscible fluids were studied experimentally. The dependence of the internal-wave transmission coefficient
on the position of the center of the cylinder relative to the pycnocline and on the ratio of the cylinder diameter to the
fluid-layer thickness was obtained. The effects of the pycnocline thickness and the depth of the center of the cylinder on
the value of the hydrodynamic loads were studied. Visualization of the flow structure was performed.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 6, pp. 36–44, November–December, 2005. 相似文献
102.
The physical mechanisms of development of hydrodynamic instability during high-velocity impact are analyzed analytically and using numerical simulation. A new mechanism of development of instability based on the assumption of the existence of initial perturbations on the surfaces of the colliding plates is proposed. The progressive displacement of the maximum of the specific surface mixed mass from the shortwave to the longwave spectrum range and the self-similarity of the variation of the interface are established. 相似文献
103.
S. Madruga C. Pérez–García G. Lebon 《Theoretical and Computational Fluid Dynamics》2004,18(2-4):277-284
We study theoretically the stability of two superposed fluid layers heated laterally. The fluids are supposed to be immiscible, the interface undeformable and of infinite horizontal extension. Combined thermocapillary and buoyancy forces give rise to a basic flow when a temperature difference is applied. The calculations are performed for a melt of GaAs under a layer of molten B2O3, a configuration of considerable technological importance. Four different flow patterns and five temperature configurations are found for the basic state in this system. A linear stability analysis shows that the basic state may be destabilized by oscillatory motions leading to the so-called hydrothermal waves. Depending on the relative height of the two layers these hydrothermal waves propagate parallel or perpendicular to the temperature gradient. This analysis reveals that these perturbations can alter significantly the liquid flow in the liquid-encapsulated crystal growth techniques. PACS 47.20.Dz, 47.20.Bp, 47.54.+r, 47.27.Te, 44.25.+f, 47.20.Ma 相似文献
104.
In order to describe the basic phenomenon of miscible grout propagation during the injection in a saturated and deformable porous medium, a general mathematical model was proposed, which accounts for the existing coupling between the fluid flow analysis, the miscible grout transport, and the solid skeleton deformation, leading to a realistic prediction of the injected zone. The development of the model was made concurrently with laboratory experiments to determine the model parameters. This paper describes the determination of the longitudinal dispersivity during the transport of a micro-cement grout injected in a one-dimensional soil column, by relying on image processing analysis. The application concerned here is the injection of soils for improving their properties, that is, to reduce permeability, increase mechanical strength or reduce the deformability. The longitudinal dispersion coefficient is an essential parameter governing the mixing process and the evolution of the transition zone, and thus the injection efficiency. Finally, the comparison between simulated results from the developed model and experimental data, essential to validate the model from a phenomenological standpoint, is made. 相似文献
105.
This paper focuses on an experimental investigation of different types of insulated hollow-brick cavity walls, i.e., walls
with a door opening, with a window opening and without any opening, characterized with different tie bar arrangements, subjected
to slowly applied cyclic loads. The cracking and damage patterns, strength and stiffness degradation and deterioration, energy
dissipation capacity and hysteretic feature are analyzed. Based on the experimental results, the formulae of calculation for
the cracking load and the ultimate load of cavity wall are mathematically established. The evaluation equation of strength
and stiffness degradation of walls is presented and its parameters are numerically given from regression results. The original
characteristic curves of recovery force-displacement of actual specimens under cyclic loads are discussed, and then a standard
recovery force-displacement model is suggested with convenient forms for implementation. 相似文献
106.
107.
讨论了温升时所研制的大型精密离心机液体静压轴承工作模式、光栅测量系统、失准角的影响,并对离心机热源进行了计算。在理论分析和实验研究的基础上,给出了温升问题的解决方法,并提出了今后精密离心机的改进建议。 相似文献
108.
角接触球轴承是航天器的许多重要功能的实施部件,因而对其润滑性能的要求极为严格,迫切需要弄清其润滑失效机理。因此,对MoS2溅射膜润滑的C6205球轴承进行了寿命试验,进而对经过丙酮超声清洗的各元件工作面的形貌和组成作了系统分析。 相似文献
109.
控制力矩陀螺用磁轴承磁力参数的辨识 总被引:1,自引:0,他引:1
提出一种实用的闭环辨识方法—磁中心变位移法,可以对控制力矩陀螺用磁轴承的磁力参数进行辨识。这种方法通过在磁中心处改变转子位移,得出不同位移时的电流值,再用这些值进行最小二乘辨识,得出所求的磁力参数。辨识出的电磁力模型中代入实际数据所得输出值与磁轴承实际输出数据非常吻合,证明了辨识所得磁力参数的准确性,并且用所得到的磁力参数指导磁轴承系统控制器参数的选择,使之更好地对磁轴承进行控制。实验证明,调整后的参数使转子在 30 060 r/mim 时仍能稳定地悬浮在给定位置,验证了所得磁力参数的准确性。 相似文献
110.
A. G. Petrov 《Journal of Applied Mechanics and Technical Physics》2003,44(1):1-16
Investigation of the plane–parallel motion of particles of an incompressible medium reduces to investigation of a Hamiltonian system. The Hamiltonian function is a stream function. The timeperiodic mixing of an incompressible medium is described by a timeperiodic Hamiltonian function. The mixing of the medium is associated with dynamic chaos. Transition to dynamic chaos is studied by analysis of the positions of Lagrangian particles at times divisible by the period — Poincaré recurrence points. The set of Poincaré recurrence points is studied with the use of Poincaré mapping on the phase flow. A method for constructing Poincaré maps in parametric form is proposed. A map is constructed as a series in a small parameter. It is shown that the parametric method has a number of advantages over the generating function method is shown. The proposed method is used to examine the motion of particles of an incompressible viscous fluid layer between two circular cylinders. The outer cylinder is immovable, and the inner cylinder rotates about a point that does not coincide with the centers of both cylinders. An optimal mode for the motion is established, in which the area of the chaotic region is maximal. 相似文献