Pdf modeling twophase flow in horizontal pipe bends. Gasliquid twophase flow regimes for vertical pipes. However, the influence of the relative roughness becomes more evident at higher vapour quality and higher mass flux. The transition from horizontal to vertical pipe causes disruptions in the flowfield resulting in flow induced unsteady forces as well as additional losses in. Relief valves for twophase gas liquid flow, chemical engineering, 109, no.
Flow of the liquid may be viscous and phase is assumed to flow alone, and phase, must. Identify two phase separated flow regimes in horizontal and vertical pipe flows. Introduction critical two phase flow can occur when liquid and gas phase mixture leaks from a pipe or a vessel at a higher pressure to a pipe, a vessel or an atmosphere at a lower pressure through an opening. A comprehensive model is formulated to predict the flow behavior for upward two phase flow. Actually, the terms two component flow and twophase flow are often used rather loosely in the literature to mean liquidgas flow and liquidvapor flow respectively. Flow regimes and phase equilibrium phase equilibrium is obtainable at a constant pressure. Distribution of two phase flow in a distributor 45 journal of engineering science and technology february 2012, vol. Two phase flow horizontal pipe line sizing and pressure drop calculation for two phase fluid flowing through a horizontal pipe. A local velocity which has a constant mean value but also has a statistically random fluctuating component due to turbulence in the flow. You may not modify, copy, distribute, transmit, display, reproduce, publish, license, create derivative works from, transfer, or sell any information from the book. Search for library items search for lists search for contacts search for a library. Chemical engineers frequently encounter the flow of a mixture of two fluids in pipes. Twophase gasliquid pipe flow and relief sizing aiche. Hydraulic fluid flow two phase calculations engineering.
Processes in power systems involve various forms of two phase flow, and it is specially important when dealing with accident scenarios in nuclear power plants. In this study, adiabatic airwater two phase flow experiments in a 203. Chapter 3 flow analysis memorial university of newfoundland. Actually, the terms two component flow and two phase flow are often used rather loosely in the literature to mean liquidgas flow and liquidvapor flow respectively. Actually, the terms twocomponent flow and twophase flow are. Model based on experiments with airwater flow for various pipe inclinations. Pdf numerical analysis of two phase flow patterns in. Pdf effect of flow patterns on twophase flow rate in vertical pipes. Studies will be made on how to express losses caused by a change in the cross sectional area of a pipe, a pipe bend and a valve, in addition to the frictional loss of a pipe. A study of two phase flow in inclined pipes, jpt may 1973, 607617.
Notes on twophase flow, boiling heat transfer, and. Gasliquid flow in inclined pipes was investigated to determine the erect of pipe inclination angle on liquid holdup and pressure loss. Pdf gasliquid twophase flow in inclined pipes researchgate. Vertical two phase flow geometries can be classified as bubble, slugannular, transition, and annularmist, depending on the gasliquid ratio. Thus, slug flow constitutes the most serious implication in two phase flow. The fact that each phase in the two phase flow problem has its own properties, velocity, and temperature makes the solution of two phase flow and heat transfer problems very challenging. As in our own bodies, where the veins and arteries move blood through the pumping. The areas of the two pipes are proportional to the void fraction. Such high velocities can cause a phenomenon known as erosion corrosion in equipment and piping systems.
Slug flow occurs when the dispersed gas bubbles combine to form bigger bubbles. The design of two phase pipe flow systems is often a complex phenomenon. Nonflashing lines have two phase flow, and carry both condensate and steam from the equipment to the trap. Depending upon the flow regime, the liquid in a two phase flow system can be accelerated to velocities approaching or exceeding vapour velocities. Two phase flow literature reports a plethora of correlations for determination of flow patterns, void fraction, two phase pressure drop and nonboiling heat transfer correlations.
This map is based on a semitheoretical method, and it is computationally more difficult to use than other flow maps. However, the validity of a majority of these correlations is restricted over a narrow range of two phase flow conditions. Guidelines for line sizing for two phase flow in horizontal pipe checalc chemical engineering calculations to assist process, plant operation and maintenance engineers. Pressure variations are inevitable in most two phase. The two phases can exist as combinations of solid, gas andor liquid phases. Two phase flow models comparison and analysis yun zhe liu 3520 2. Flow of helium ii, or of electrons in a superconductor, thought of as consisting of two interpenetrating, noninteracting fluids, a superfluid component which exhibits no resistance to flow and is responsible for superconducting properties, and a normal component, which behaves as does an ordinary fluid or as conduction electrons in a nonsuperconducting metal. Study on oilwater twophase flow in horizontal pipelines. A fractional phasefield model for twophase flows with. The subject of multiphase flows encompasses a vast field, a host of different technological. A comprehensive mechanistic model for upward two phase flow in wellbores a. Twophase 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 twophase flows where one phase is present in the form of particles, droplets, or bubbles in a continuous carrier phase i. Types of gasliquid flow bakers map for gasliquid flow calculation methodology references 3. Notes on twophase flow, boiling heat transfer, and boiling.
Argonwater is an instance of two phase two component flow. Iost of the scientific investigation of twophase flow has been conducted in. The flow physics inside the pipe was solved using computational fluid dynamics cfd solver ansys fluent. The result demonstrated that the frictional pressure drop increases with increasing relative roughness of the pipe. Many correlations have been developed for predicting two phase flow pressure gradients which differ in the manner used to calculate the three terms of pressure. The need for two phase flow measurement in the power generation industry has been significantly increased over the last few years. The design of two phase liquidgas pipe flow systems is a complex process. The areas of the two pipes are proportional to the void fraction numerous. Department of chemical and biomolecular engineering. The multiphase flow in wellbores and pipe lines is handled by several multiphase flow equations including beggsbrill, hagedornbrown, hasankabir, and duns and ros. Understanding the challenges of two phase flow 2 phase flow is difficult for all flowmeters all flow meter technologies have limitations, and most have a tough time with two phase flow, such as air mixed in a liquid stream.
Laminar flow is characterized by little mixing of the flowing fluid and a parabolic velocity profile. A wide range of models have been developed for two phase flow systems. Two phase flow splitting in piping branches by michael steven quintana s. The engineers developed the terminology rather than the chemists. Mean volumetric void fraction is a key parameter to characterise two phase flows. Twophase fluid flow guideline to pipe sizing for two phase flow liquid gas author. A study of twophase flow in inclined pipes onepetro. Prediction of optimum length to diameter ratio for twophase fluid. Elements of two phase flows with emphasis on liquid vapour phase change phenomenon by pradeep kumar. Experimental investigation of twophase flows in large. Two phase flow article about two phase flow by the free.
There are two basic flow regimes for flow of a singlephase fluid. Liquidliquid twophase flow systems neimabrauner school of engineering, telaviv university telaviv 69978, israel 1 generaldescriptionofliquidliquidflows. In fluid mechanics, twophase flow is a flow of gas and liquid a particular example of multiphase flow. When these two states act in randomlike manner, unstable flow starts occurring in the form of oscillations and or flow reversals, inducing pressure and velocity fluctuations, resulting in undesirable mechanical vibration of components in piping system. Twophase flow studies in horizontal pipes with special reference. Pdf during twophase gasliquid flow in pipelines, the fluids may take. Correlations for liquid holdup and friction factor were developed for predicting pressure gradients for two phase flow in pipes at all angles for many flow pressure gradients for two phase flow in pipes at all angles for many flow conditions. Nazario, twophase flashing flow methods and comparisons, journal of loss prevention in the process industries, 1990, 3, 2, 253crossref. A few other empirical correlations are used to describe the multiphase flow through the choke. Toward the end of these notes, well see some examples of these regimes. Numerical simulation of twophase flow regime in horizontal. There are many applications in the chemical and process industries, ranging from the flow of mixtures of oil and gas. A gas lift option is also included with the program.
In the homogeneous model, the two phases are assumed to be travelling at the same velocity in the channel and the flow is treated as being analogous to a single phase flow see article on multiphase flow. Flowpatterns flows of two immiscible liquids are encountered in a diverse range of processes and. Two phase flow liquidgas system design may 21, 2019 martin king. Twophase flow is a difficult subject principally because of the complexity of the form in which the two fluids exist inside the pipe, known as the flow regime. Pressure drop and flow pattern definition data were obtained over a large range of mass qualities. The two phase flow patterns in vertical flow are somewhat different from those occurring in horizontal or slightly inclined flow. Two phase flow is any type of flow containing more than one phase of liquid, gas or solid. The general geometry of horizontal pipe flow for the case studies modeled is shown in figure 4. This is mainly because the reliable measurements of the two phase. May 09, 2011 two phase flow in a pipe simulated with openfoam. Water fractions in the output stream increase materially during the producing life of a well and many wells exist from which economic production can still persist with water volume fractions in the liquid phase in excess of 90%. It can be common practice for engineers to use template design calculation sheets for two phase systems.
Downward two phase flow in large diameter pipes appears in numerous industrial applications and nuclear reactor accidents. Pdf simplified transient twophase model for pipe flow. Liquidgas or liquidvapor mixtures are encountered in condensers and evaporators, gasliquid reactors, and. Pdf of void fraction that showed traditional features of slug flow one peak at lower void. Fluidflow is used by engineers to calculate pressure losses and flow distribution in two phase pipe flow. Airwater is an example of two phase multi component flow. Typical plots of velocity time histories for laminar flow, turbulent flow, and the region of transition between the two are shown below. Two phase flow analyses are critical to successful design and operations of two phase and multiphase pipe flow applications found in major industrial fields, such as petroleum, nuclear, chemical. Correlations for liquid holdup and friction factor were developed for predicting pressure gradients for two phase. Introduction some of the important features of the flow of two phase mixtures composed of a liquid together with a gas or vapour are discussed in this section.
One of the aspects that play a role in the acoustics in pipes is the in. Twophase flow and pressure drop in flow passages of compact. In addition, when gasliquid mixtures flow at high velocities serious erosion problems can arise and it is necessary for the designer to restrict flow velocities to avoid serious damage to equipment. Frictional pressure drop of gas liquid twophase flow in pipes. Pdf on sep 1, 2007, ahad ghaemi and others published modeling two phase flow in horizontal pipe bends find, read and cite all the research you need on researchgate. Flow type the flow type of two phase liquidgas flow can be characterized into one of seven types shown. The fluid dynamic characteristics of a liquid and air mixture are extremely complex, and to a large degree are still. Void fraction measurement of gasliquid twophase flow. The average velocity of gas phase flow ug is defined as the volumetric flow rate of gas phase q g divided by the pipe crosssectional area occupied by the gas phase flow ag. The discharge of twophase flashing flow in a horizontal duct. Many researches were carried out to correlate differential pressure and void fraction in two phase. Some engineers believe that condensate return pipes are completely filled with condensate. Twophase flow refers to the interactive flow of two distinct phases with common interfaces in a channel, with each phase representing a mass or volume of matter. The most common twophase flow regime is called slug flow, in which pipe cross section is filled alternatively with gas and liquid.
A comprehensive mechanistic model for upward twophase. The separated flow model considers the two phases to be artificially separated into two streams, each flowing in its own pipe. A new prediction model for frictional pressure drop of two phase flow in pipes. Void fraction measurement of gasliquid twophase flow from. Any flow involving two of the three phases is a twophase flow. Bubble flow, slug flow and emptyfullempty flow in fluid applications duration. Depending upon the flow regime, the liquid in a twophase flow system can be accelerated to velocities approaching or exceeding vapour velocities. Types of phase flows and gas liquid system piping guide. This webinar covers methods for identifying flow regimes and determining friction loss in two phase distributed and homogeneous gasliquid pipe flows and sizing relief valves for frozen and flashing homogeneous two phase flow.
Although the wall elasticity is negligible for very stiff steel pipes that are. Leung, twophase flow discharge in nozzles and pipes a unified approach, journal of loss prevention in the process industries, 1990, 3, 1, 27crossref. Braga 5 evaluated air and water flow in a pipe with 1250 meters length. This lecture discusses about different flow patterns possible in gasliquid flow through horizontal and vertical pipes including phase change applications. Numerical methods such as volumeoffluid 3,4 and levelset 4,5 have been successfully employed to simulate two phase flows. These processes are frequently encountered in the process industries. Their respective distribution takes on some commonly observed flow structures, which are defined as two phase flow patterns that have particular identifying characteristics. Study of twophase flow in pipe bends by jose ramon castillo submitted to the department of mechanical engineering on may 20, 1957, in partial fulfillment of the requirements for the degree of master of science.
Slug flow belongs to a class of intermittent flow that has very distinctive features and it occurs under special circumstances of two phase gasliquid flow. Flow quality flow rate flow regime low low and intermediate bubbly high dispersed bubbly intermediate low and intermediate plugslug. Talk on elements of twophase flows with emphasis on. Micro motion coriolis flow and density measurement 2,997. My goal for this lecture is to lay down basic terminology for two phase flow, and give a feeling for what various void fractions represent. Combining previous both expressions gives an equation for the upper limit. Twophase fluid flow guideline to pipe sizing for twophase flow liquid gas author. For two phase flow, the respective distributions of the liquid and vapor phases in the flow channel is the important aspect of their description. Although their operational condition was a single phase flow in turbulent condition, the presented method of analysis on pipe elbow can be applicable to two phase flow, especially for bubbly flow case since the flow field in that regime is governed by the liquid phase, which creates pressure fluctuations due to secondary flow and dean vortex. Using the homogeneous flow pressure drop method, calculate the two phase pressure drop for up flow in a vertical tube of 10 mm internal diameter that is 2 m long. A computational fluid dynamics study of two phase dispersed flow of viscous oil and water in a horizontal pipe.
Results and discussion the experimental conditions are plotted on flow pattern maps as shown in figs. Flow quality flow rate flow regime low low and intermediate bubbly high dispersed bubbly. Pdf in order to understand the behaviour of twophase flow in inclined pipes, an extensive programme of work has been undertaken using the inclinable. The simultaneous flow of oil and water in pipelines is a common occurrence in the petroleum industry. Numerical analysis of two phase flow patterns in vertical and horizontal pipes.
Two phase flow experiments were performed with airwater mixtures in a small rectangular channel measuring 9. Two phase flow in piping system significance and usage. Multiphase flow assurance the free version of the book is for your personal and noncommercial use only. Flashing lines also have two phase flow carrying both drained. In some cases these velocities are higher than desirable for a process piping system. This pressure becomes important for designing pipe sizes, determining pump requirements, and addressing safety concerns. Multiphase flow is important in many areas of chemical and process.