Journal ArticleDOI
Physical aspects of the relaxation model in two-phase flow
Z. Bilicki,J. Kestin +1 more
TLDR
In this paper, the authors explore the potential of the homogeneous relaxation model (HRM) as a basis for the description of adiabatic, one-dimensional, two-phase flows.Abstract:
The paper explores the potential of the homogeneous relaxation model (HRM) as a basis for the description of adiabatic, one-dimensional, two-phase flows. To this end, a rigorous mathematical analysis highlights the similarities and differences between this and the homogeneous equilibrium model (HEM) emphasizing the physical and qualitative aspects of the problem. Special attention is placed on a study of dispersion, characteristics, choking and shock waves. The most essential features are discovered with reference to the appropriate and convenient phase space Ω for HRM, which consists of pressure P , enthalpy h , dryness fraction x , velocity w , and length coordinate z . The geometric properties of the phase space Ω enable us to sketch the topological pattern of all solutions of the model. The study of choking is intimately connected with the occurrence of singular points of the set of simultaneous first-order differential equations of the model. The very powerful centre manifold theorem allows us to reduce the study of singular points to a two-dimensional plane Π , which is tangent to the solutions at a singular point, and so to demonstrate that only three singular-point patterns can appear (excepting degenerate cases), namely saddle points, nodal points and spiral points. The analysis reveals the existence of two limiting velocities of wave propagation, the frozen velocity a f and the equilibrium velocity a e . The critical velocity of choking is the frozen speed of sound. The analysis proves unequivocally that transition from ω a f to w > a f can take place only via a singular point. Such a condition can also be attained at the end of a channel. The paper concludes with a short discussion of normal, fully dispersed and partly dispersed shock waves.read more
Citations
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Journal ArticleDOI
The non-equilibrium relaxation model for one-dimensional flashing liquid flow
TL;DR: In this paper, the authors presented a correlation for the relaxation time which is a closure law for the homogeneous relaxation model (HRM), which takes into account the non-equilibrium evaporation leading to the metastable liquid conditions.
Journal ArticleDOI
Multi-dimensional simulation of thermal non-equilibrium channel flow
TL;DR: In this article, the Homogenous Relaxation Model (HRM) is used to study thermal non-equilibrium, two-phase flows with flash-boiling and condensation.
Journal ArticleDOI
Computational modelling of flash boiling flows: A literature survey
Yixiang Liao,Dirk Lucas +1 more
TL;DR: A review of published work on the physics and modelling of flashing flows is presented in this paper, where the authors provide a brief but comprehensive overview of available theoretical models for these sub-phenomena as well as general modelling frameworks.
Journal ArticleDOI
A Model for Choked Flow-through Cracks With Inlet Subcooling
TL;DR: In this article, a model to predict the mass flow rate has been developed and has been successfully validated, taking into account the persistence of some metastable liquid in the crack and the special flow pattern which appears in such particular geometry.
References
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Journal ArticleDOI
Elements of gasdynamics
TL;DR: Elements of gasdynamics, Elements of gas dynamics, this paper, elements of gas dynamics, elements of gases, gas dynamism, and elements of dynamism.
Journal ArticleDOI
Thermophysical properties of fluid D2O
TL;DR: In this paper, the authors present a compendium of thermophysical properties of deuterium oxide (heavy water) and show that the properties are represented by equations which can be readily programed on a computer and incorporated in data banks.