共查询到20条相似文献,搜索用时 109 毫秒
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对于水平面上的池内饱和沸腾传热机理,本文提出了一种新的微液层理论模型。与以前的理论模型不同的是,微液层模型给出了传热面上气-液-固接触的动态构造。饱和沸腾换热的主要机理在于动态微液膜的蒸发并与单个气泡的动力学过程密切相关。该模型能很好地预测充分发展的核沸腾换热曲线。由沸腾曲线上的极大值而很自然地导出临界热负荷。理论计算结果和已有的实验的结果相当吻合。 相似文献
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A Thellung 《Annals of Physics》1980,127(2):289-301
In the customary microscopic derivation of the two-fluid equations of liquid He II explicit use is made of the assumption that an elementary excitation of wave vector k carries a momentum ?k. In this paper it is shown that phonons in a liquid can be defined as carrying momentum ?k (Eulerian phonons) or zero momentum (Lagrangian phonons). A careful analysis—in particular of the concept “velocity of the bearer fluid”—shows that the two-fluid equations turn out to be the same in either case. 相似文献
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A new formulation of Kapila’s five-equation model for inviscid, non-heat-conducting, compressible two-fluid flow is derived, together with an appropriate numerical method. The new formulation uses flow equations based on conservation laws and exchange laws only. The two fluids exchange momentum and energy, for which exchange terms are derived from physical laws. All equations are written as a single system of equations in integral form. No equation is used to describe the topology of the two-fluid flow. Relations for the Riemann invariants of the governing equations are derived, and used in the construction of an Osher-type approximate Riemann solver. A consistent finite-volume discretization of the exchange terms is proposed. The exchange terms have distinct contributions in the cell interior and at the cell faces. For the exchange-term evaluation at the cell faces, the same Riemann solver as used for the flux evaluation is exploited. Numerical results are presented for two-fluid shock-tube and shock-bubble-interaction problems, the former also for a two-fluid mixture case. All results show good resemblance with reference results. 相似文献
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I. F. Barna A. R. Imre L. Rosta F. Mezei 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,66(4):419-426
Two-phase flow calculations are presented to investigate the thermo-hydraulical effects
of the interaction between 2 ms long 1.3 GeV proton pulses with a closed mercury loop which
can be considered as a model system of the target of the planned European Spallation
Source (ESS) facility. The two-fluid model consists of six first-order partial
differential equations that present one dimensional mass, momentum and
energy balances for mercury vapor and liquid phases are capable
to describe quick transients like cavitation effects or shock waves. The absorption of the proton beam is represented as instantaneous
heat source in the energy balance equations.
Densities and internal energies of the mercury liquid-vapor system is calculated from the van der Waals equation, but general
method how to obtain such properties using arbitrary equation of state is also presented.
A second order accurate high-resolution shock-capturing numerical scheme
is applied with different kind of limiters in the numerical calculations.
Our analysis show that even 75 degree temperature heat shocks cannot cause considerable cavitation effects in mercury. 相似文献
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介绍了过冷沸腾换热的数值模拟方法以及在EAST第一壁组件冷却系统中的应用.采用双流体模型,系统分析了过冷沸腾壁面换热过程中存在的各种换热模式,给出了Fluent软件封闭关系式中所需的质量、动量以及能量的交换项的形式.采用用户自定义函数(UDF)模拟壁面沸腾气化过程,对提出的模拟方法与已发表的实验数据对比进行了校核,得出合理的结论.最后分析了过冷沸腾两相流在EAST第一壁中的工程应用,模拟了热沉冷却结构的沸腾换热现象.为EAST PFCs的冷却结构优化提供了依据. 相似文献
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《Physics letters. A》2001,289(6):333-336
We evaluate the kinetic energy and the momentum distribution of a Bose-condensed cloud of hydrogen gas inside a Ioffe–Pritchard trap, using a semiclassical two-fluid approach. The relationship between temperature and mean kinetic energy of the gas depends sensitively on the shape of the confining potential. 相似文献
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José Jesus Rodríguez-Núñez Ricardo Tello-Llanos 《International Journal of Theoretical Physics》1991,30(6):857-863
We present a theoretical treatment of the Landau two-fluid model of superfluidity in liquid helium by means of the Dirac formalism. We introduce hydrodynamic considerations in a natural way by means of Lagrange multipliers. All constraints in phase space, in Dirac's sense, are second class and, as a consequence, the Dirac bracket differs strongly from the Poisson bracket. We calculate the Dirac bracket of the canonical variables, putting special interest on the density and the momentum density of the system. Our results generalize the results given by Dzyaloshinskii and Volovik and correct other published results. 相似文献
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Kikuchi Y de Bock MF Finken KH Jakubowski M Jaspers R Koslowski HR Kraemer-Flecken A Lehnen M Liang Y Matsunaga G Reiser D Wolf RC Zimmermann O;TEXTOR-team 《Physical review letters》2006,97(8):085003
The magnetic field penetration process into a magnetized plasma is of basic interest both for plasma physics and astrophysics. In this context special measurements on the field penetration and field amplification are performed by a Hall probe on the dynamic ergodic divertor (DED) on the TEXTOR tokamak and the data are interpreted by a two-fluid plasma model. It is observed that the growth of the forced magnetic reconnection by the rotating DED field is accompanied by a change of the plasma fluid rotation. The differential rotation frequency between the DED field and the plasma plays an important role in the process of the excitation of tearing modes. The momentum input from the rotating DED field to the plasma is interpreted by both a ponderomotive force at the rational surface and a radial electric field modified by an edge ergodization. 相似文献
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