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Different modes of two-phase flows. In fluid mechanics, two-phase flow is a flow of gas and liquid — a particular example of multiphase flow.Two-phase flow can occur in various forms, such as flows transitioning from pure liquid to vapor as a result of external heating, separated flows, and dispersed two-phase flows where one phase is present in the form of particles, droplets, or bubbles in ...
In fluid dynamics, the Ledinegg instability occurs in two-phase flow, especially in a boiler tube, when the boiling boundary is within the tube.For a given mass flux J through the tube, the pressure drop per unit length (which typically varies as the square of the mass flux and inversely as the density, i.e., as /) is much less when the flow is wholly of liquid than when the flow is wholly of ...
The Lockhart–Martinelli parameter is a dimensionless number used in internal two-phase flow calculations. It expresses the liquid fraction of a flowing fluid. Its main application is in two-phase pressure drop and boiling/condensing heat transfer calculations.
The flow rate can be converted to a mean flow velocity V by dividing by the wetted area of the flow (which equals the cross-sectional area of the pipe if the pipe is full of fluid). Pressure has dimensions of energy per unit volume, therefore the pressure drop between two points must be proportional to the dynamic pressure q.
There are a number of correlations for slip ratio. For homogeneous flow, S = 1 (i.e. there is no slip). The Chisholm correlation [2] [3] is: = The Chisholm correlation is based on application of the simple annular flow model and equates the frictional pressure drops in the liquid and the gas phase.
In particular, Lockhart and Martinelli (1949) [6] presented a model for frictional pressure drop in horizontal, separated two-phase flow, introducing a parameter that is still utilised today. Between 1950 and 1960, intensive work in the aerospace and nuclear sectors triggered further studies into two-phase flow.
Dimensionless numbers (or characteristic numbers) have an important role in analyzing the behavior of fluids and their flow as well as in other transport phenomena. [1] They include the Reynolds and the Mach numbers, which describe as ratios the relative magnitude of fluid and physical system characteristics, such as density, viscosity, speed of sound, and flow speed.
Pressure drop (often abbreviated as "dP" or "ΔP") [1] is defined as the difference in total pressure between two points of a fluid carrying network. A pressure drop occurs when frictional forces, caused by the resistance to flow, act on a fluid as it flows through a conduit (such as a channel, pipe , or tube ).