共查询到20条相似文献,搜索用时 179 毫秒
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海洋油气资源钻探中隔水管的弯曲对钻柱振动以及钻进特性有特别的影响。为得到隔水管弯曲对钻柱振动的影响规律,对南海已钻深水井使用非线性有限元软件建立全井钻井数值计算模型,研究获得了不同垂深时隔水管弯曲对钻柱振动特性的影响规律。研究表明:隔水管弯曲会加剧钻柱的振动,钻柱振动加剧会导致钻井能耗上升、钻头切削能力下降并且会加快钻柱疲劳;当隔水管的弯曲达到某临界值,钻柱与隔水管间的接触力会陡增;井口的钩载越大,隔水管弯曲带来的井口钩载波动量越大;井越深,隔水管弯曲对全井钻柱最大弯矩和钻头切削能力的影响越小。 相似文献
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Jiří Mls 《Transport in Porous Media》1987,2(6):615-621
A general theorem on the derivative of the volume average is formulated and proved. Conditions for the existence of the derivative are presented and discussed. This is done in order to give a better base to the theory of spatial averaging.Latin Letters
E
3
three-dimensional vector space over the field of real numbers
-
K, K(x)
averaging domain
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G, G
w, Gs
open sets in E
3; components of the two-phase system
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C
1(G)
the set of functions 1-times continuously differentiable in G
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W1/2(G)
Sobolev space
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V
volume of the domain K
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f
function defined in G, G
w
- K
infi
sup*
(x), K
infi
sup–
(x)
special parts of K(x)
Greek Letters
boundary of G, G
w, Gs; w-s interface
-
ij
Kronecker delta
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v
unit outward normal of G, G
w
-
j
j-dimensional Lebesgue measure
Other
M
closure of a set M in the metric space E
3
- f
phase average of f for the w-phase
- (u, v)
scalar product of u, v in E
3
-
one-sided derivatives 相似文献
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The question of whether the nonlinear Timoshenko-type theory of shells can be applied to the study of the initial postcritical behavior of a rod under compression is considered. The Koiter asymptotic theory in the Budyanskii form is used. The exact solution of the problem is obtained and a formula for the coefficient of postcritical behavior allowing for the effect of lateral-shear strains is derived. It is shown that the expressions (specified to within cubic terms) for lateral-shear strains and curvature permit us to use the nonlinear theory of shells to analyze the initial supercritical behavior of rods 相似文献
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岳珠峰 《应用数学和力学(英文版)》2004,25(8):887-893
Crystallographic plasticity was applied to study the initiation of micro cracks on the smooth surface of polycrystalline under uniform applied stress. Even under the uniform external stress, due to the different crystallographic orientations of the grains in the polycrystalline, there is un-uniform stress distribution and the deformation is also not uniform. Under the fatigue loading, the roughness increases with the number of fatigue, and deformation will localize in some places, where micro cracks form. 相似文献
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G. A. Lyubimov 《Fluid Dynamics》1990,25(5):696-704
In connection with the construction of Leningrad's flood defenses the flow in the mouth of River Neva has been investigated on hydraulic models of different scales both unpressurized (see, for example, [1, 2]) and pressurized (see, for example, [3]). Since the results of these investigations are being intensively debated in connection with the discussion of the effect of defensive structures on the ecology of the Leningrad region, it is important to analyze the scientific basis for the hydraulic modeling of such flows.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 5, pp. 57–65, September–October, 1990. 相似文献
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Experimental investigation of the influence of the flow structure on the aerodynamic coefficients of the IXV vehicle 总被引:1,自引:0,他引:1
T. Gawehn D. Neeb F. Tarfeld A. G��lhan M. Dormieux P. Binetti T. Walloschek 《Shock Waves》2011,21(3):253-266
In the framework of the ESA Future Launchers Preparatory Program (FLPP) an experimental study on the aerodynamic behavior
during the re-entry phase of the Intermediate eXperimental Vehicle (IXV) configuration was conducted in the DLR hypersonic
wind tunnel H2K in Cologne. Tests were carried out at Mach 6.0 and 8.7 with different flap deflection angles and the angle
of attack varied continuously between 20° and 55° to investigate the flow topology as well as the aerodynamic forces and moments
and the surface pressure distribution. The experimental data show that depending on the combination of the flap deflection
angle (δ
L/R) and angle of attack (α) the complex flow structure in the vicinity of the flaps significantly influences the vehicle’s aerodynamic
coefficients. An analysis of this shock/shock and shock/boundary layer interaction causing flow separation with reattachment
is performed. 相似文献