Fluid Dynamics and Pressure Drop Prediction of Two-Phase Flow Through Sudden Contractions

2021 ◽  
Author(s):  
Saroj Kumar Patra ◽  
Manmatha K. Roul ◽  
Prashant Kumar Satpathy ◽  
Ashok Kumar Barik
Keyword(s):  
Fluid Dynamics ◽  
Pressure Drop ◽  
Mass Flow ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Area Ratio ◽  
Phase Flow ◽  
Two Phase ◽  
Vena Contracta ◽  
Flow Quality

Abstract The aim of the present study is to investigate fluid dynamics and pressure drop across sudden contractions in a two-dimensional, axisymmetric pipe carrying a two-phase mixture of air (secondary phase) and water (primary phase), using the Eulerian-Eulerian model of the multi-phase flow physics to solve the mass, momentum, volume fraction and turbulent quantities with relevant boundary conditions in a finite volume framework. The realizable per-phase k-e and Reynolds stress models have been used as the closure for turbulent quantities along with enhanced wall function for the near-wall treatment. The effects of various parameters such as mass flux, mass flow quality, area ratio (0.056-0.619), flow directions (horizontal/vertical), and system pressure on the two-phase pressure drops due to a contraction in the pipe have been quantified. For both the single and two-phase flows, it has been observed that the pressure drop decreases with area ratio, and increases with mass flux and mass flow quality of two-phase flow. The vena contracta for a single-phase flow was found. But for two-phase flow, neither the vena contracta nor the recirculation zone has been observed, as the mass quality exceeds above 50%. A higher pressure drop has been observed for vertical pipes as compared to the horizontal pipes. The present numerical results have also been validated with published experimental results, believed to be one of the alternatives to the costly experimental methods for predicting the flow dynamics and pressure drop.

Research on Two-Phase Flow Instability in Evaporator of Refrigeration System

2010 ◽  
Author(s):  
Nan Liang ◽  
Changqing Tian ◽  
Shuangquan Shao
Keyword(s):  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Density Wave ◽  
Phase Flow ◽  
Constant Mass ◽  
Refrigeration System ◽  
Two Phase

As one kind of fluid machinery related to the two-phase flow, the refrigeration system encounters more problems of instability. It is essential to ensure the stability of the refrigeration systems for the operation and efficiency. This paper presents the experimental investigation on the static and dynamic instability in an evaporator of refrigeration system. The static instability experiments showed that the oscillatory period and swing of the mixture-vapor transition point by observation with a camera through the transparent quartz glass tube at the outlet of the evaporator. The pressure drop versus mass flow rate curves of refrigerant two phase flow in the evaporator were obtained with a negative slope region in addition to two positive slope regions, thus making the flow rate a multi-valued function of the pressure drop. For dynamic instabilities in the evaporation process, three types of oscillations (density wave type, pressure drop type and thermal type) were observed at different mass flow rates and heat fluxes, which can be represented in the pressure drop versus mass flow rate curves. For the dynamic instabilities, density wave oscillations happen when the heat flux is high with the constant mass flow rate. Thermal oscillations happen when the heat flux is correspondingly low with constant mass flow rate. Though the refrigeration system do not have special tank, the accumulator and receiver provide enough compressible volume to induce the pressure drop oscillations. The representation and characteristic of each oscillation type were also analyzed in the paper.

Pressure Drop in a Capillary Tube in Boiling Two-Phase Flow

2003 ◽  
Author(s):  
Fumito Kaminaga ◽  
Baduge Sumith ◽  
Kunihito Matsumura
Keyword(s):  
Pressure Drop ◽  
Vapor Phase ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Capillary Tube ◽  
Flow Boiling ◽  
Phase Flow ◽  
Two Phase ◽  
System Pressure ◽  
Phase Pressure

Two-phase pressure drop is experimentally examined in a flow boiling condition in a tube of diameter 1.45 mm using water in ranges of pressure from 10 to 100 kPa, mass flux from 18 to 152 kg/m2s, heat flux from 13 to 646 kW/m2, and exit quality from 0.02 to 0.77. Also, pressure drop in an adiabatic air-water two-phase flow is measured at atmospheric pressure using the same test section and mass flux ranges of liquid and gas as those in the flow boiling. Decreasing system pressure the pressure drop significantly increases at a given mass flux. Influence of vapor phase on the pressure drop is found to be large both in the adiabatic and the diabatic conditions. The frictional pressure drop correlation for the adiabatic two-phase flow is developed and applied to predict pressure drop in the flow boiling. But it cannot give satisfactory predictions. The Chisholm correlation calculating a two-phase pressure drop multiplier is modified to account the influence of vapor phase in a capillary tube and the modified correlation can predict the pressure drop in the flow boiling within an error of 20%.

Experimental Research on Pulsating Two-Phase Flow Pressure Drop Characteristics in Horizontal Rectangular Channel

2014 ◽  
Author(s):  
Siqi Zhang ◽  
Puzhen Gao
Keyword(s):  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Rectangular Channel ◽  
Phase Flow ◽  
Two Phase ◽  
Mean Values ◽  
Water Mass Flow Rate

In spite of most previous studies since 1970, the theory of pulsating pipe flows supported by experimental investigations has not yet completed in comparison with the well-defined theory of steady pipe flows. Therefore, it seems that there is much to be done about experimental research in this field. In order to determine the resistance characteristics of two-phase flow under pulsatile conditions, an experimental investigation on two-phase flow with periodically fluctuating flow rates in a narrow rectangular channel is carried out. A frequency inverter is used to obtain experimental conditions with different fluctuating frequencies, amplitudes and mean values of water mass flow rate. After obtaining experimental results, comparisons between experimental frictional pressure drop values and theoretical calculations have been done. Two-phase flow on pulsating conditions is far more complicated than that on steady conditions because pulsating flow is composed of two parts: a steady component and a superimposed periodical time varying component called oscillation. In this paper, the influence of different fluctuating frequencies, amplitudes and mean values of liquid and gas mass flow rate on two-phase flow pressure drop characteristics is also discussed. The results show that the total pressure drop and water mass flow rate change with the same fluctuating period except for a phase difference. The phase lag also changes with the fluctuating frequencies and amplitude. The accelerating pressure drop changes dramatically in a fluctuating period, especially at the end of acceleration. Also, the time when the acceleration pressure drop has its maximum value lags the time when the acceleration reaches its peak, mainly because of the inertial of the fluid.

Characteristics of Two-Phase Flow Pressure Drop of Propane in Horizontal Circular Small Tube

2016 ◽  
Vol 819 ◽  
pp. 371-375
Author(s):  
Agus Sunjarianto Pamitran ◽  
Sentot Novianto ◽  
T.A. Simanjuntak ◽  
Nasruddin ◽  
Muhammad Idrus Alhamid
Keyword(s):  
Heat Flux ◽  
Pressure Drop ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Saturation Temperature ◽  
Experimental Result ◽  
Phase Flow ◽  
Two Phase ◽  
Small Tube ◽  
Flow Pressure

This study experimentally investigated two-phase flow pressure drop of propane as refrigerant in horizontal small tube. Inner diameter and length of the tube were 7.6 mm and 1.07 m, respectively. In order to get pressure drop data, the experiment was conducted in various conditions of 10 to 25 kW m-2 heat flux, 200 to 628 kg m-2 s-1 mass flux, and 4.0 to 11.7°C saturation temperature. This study clearly showed the effect of heat flux, mass flux, and saturation temperature on the pressure drop of propane. This study also investigated which fluid properties gave higher effect on the frictional pressure drop due to its change over the process based on the recent experiment data. The existing pressure drop correlations were evaluated against the experimental result.

Pressure Drop Through Orifices for Single- and Two-Phase Vertically Upward Flow—Implication for Metering

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Ammar Zeghloul ◽  
Abdelwahid Azzi ◽  
Faiza Saidj ◽  
Abdelkader Messilem ◽  
Barry James Azzopardi
Keyword(s):  
Pressure Drop ◽  
Euler Number ◽  
Two Phase Flow ◽  
Acrylic Resin ◽  
Area Ratio ◽  
Superficial Velocity ◽  
Phase Flow ◽  
Open Area ◽  
Two Phase ◽  
Flow Pressure

Pressure drop has been measured for upward single- and two-phase gas–liquid flow across an orifice in a vertical pipe. A conductance probe provided average void fraction upstream of the orifice. Six orifices with different apertures/thickness were mounted in turn in a 34 mm diameter transparent acrylic resin pipe. Gas and liquid superficial velocities of 0–4 m/s and 0.3–0.91 m/s, respectively, were studied. For single-phase flow, pressure drop, expressed as an Euler number, was seen to be independent of Reynolds number in turbulent region. The Euler number increased with decreasing the open area ratio/orifice thickness and increasing velocity. The pressure drop was well predicted by the correlation of Idel'chik et al. (1994, Handbook of Hydraulic Resistances, 3rd ed., CRC Press, Boca, Raton, FL.), which uses a form of Euler number. The corresponding two-phase flow pressure drop depends on the flow pattern. Decreasing open area ratio/orifice thickness increased the pressure drop. For a given liquid superficial velocity, the pressure drop increases with gas superficial velocity except for low open area ratio where this increase is followed by a decrease beyond a critical superficial gas velocity for the high liquid superficial velocities. Relevant correlations were assessed using the present data via a systematic statistical approach. The two-phase multiplier equations of Morris (1985, “Two-Phase Pressure Drop Across Valves and Orifice Plates,” European Two Phase Flow Group Meeting, Marchwood Engineering Laboratories, Southampton, UK.) and Simpson et al. (1983, “Two-Phase Flow Through Gate Valves and Orifice Plates,” International Conference on Physical Modelling of Multiphase Flow, Coventry, UK.) are the most reliable ones.

Pressure Drop of Two-Phase Flow Boiling with R-22 and R-290 in 7.6 mm Diameter Tube

2016 ◽  
Vol 818 ◽  
pp. 23-27
Author(s):  
Agus Sunjarianto Pamitran ◽  
Nasruddin ◽  
Helmi Dadang Ardiansyah ◽  
Muhammad Idrus Alhamid
Keyword(s):  
Heat Flux ◽  
Pressure Drop ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Saturation Temperature ◽  
Phase Flow ◽  
Lower Mass ◽  
Two Phase ◽  
Experimental Pressure

The characteristics of two-phase flow boiling of R-290 are required for replacing R-22 that has been phased-out. The present study focuses on experimental pressure drop for R-22 and R-290. The experiment was run with heat flux of 5.09 kW/m2 to 19.03 kW/m2, mass flux of 114.91 kg/m2s to 751.74 kg/m2s and saturation temperature of 4.77°C to 18.12°C. The present result showed that pressure drop was affected by heat flux, mass flux and saturation temperature. Lower mass flux, heat flux and saturation temperature results in lower pressure drop. The pressure drop of R-290 is lower than that of R-22. Among the existing pressure drop prediction methods, Lokhart-Martinelli (1949) gives the best prediction for the present pressure drop data.

scholarly journals Two-Phase Flow Pressure Drop of High Quality Steam

2002 ◽  
Author(s):  
J. M. Curtis ◽  
R. D. Coffield
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Weight Fraction ◽  
Phase Flow ◽  
Sources Of Information ◽  
Two Phase ◽  
Comprehensive Survey ◽  
Flow Quality ◽  
Flow Pressure ◽  
High Reynolds

Two-phase pressure drop across a straight test pipe was experimentally determined for high Reynolds (Re) number steam having an average flow quality range of 0.995 to 1.0, where flow quality is defined as the weight fraction of the vapor in a two-phase mixture. This flow regime is representative of most steam plant piping hydraulic conditions during full power operation. The testing described has been performed in order to reduce uncertainties associated with the effects of two-phase flow on pressure drop. In addition to moisture carryover from the steam generator, two-phase flow develops in steam piping because a small fraction of the steam flow condenses due to heat loss to the surroundings. A recent comprehensive survey of the literature published by Tong and Tang (1997) identified no applicable sources of information of two-phase flow pressure drop data near the design range of interest. The two-phase flow pressure drop data obtained in this test has enabled the development of a design correlation between friction factor, Reynolds number, and flow quality.

scholarly journals Numerical Simulation of Flow Behavior within a Venturi Scrubber

2014 ◽  
Vol 2014 ◽  
pp. 1-7
Author(s):  
M. M. Toledo-Melchor ◽  
C. del C. Gutiérrez-Torres ◽  
J. A. Jiménez-Bernal ◽  
J. G. Barbosa-Saldaña ◽  
S. A. Martínez-Delgadillo ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Venturi Scrubber

The present work details the three-dimensional numerical simulation of single-phase and two-phase flow (air-water) in a venturi scrubber with an inlet and throat diameters of 250 and 122.5 mm, respectively. The dimensions and operating parameters correspond to industrial applications. The mass flow rate conditions were 0.483 kg/s, 0.736 kg/s, 0.861 kg/s, and 0.987 kg/s for the gas only simulation; the mass flow rate for the liquid was 0.013 kg/s and 0.038 kg/s. The gas flow was simulated in five geometries with different converging and diverging angles while the two-phase flow was only simulated for one geometry. The results obtained were validated with experimental data obtained by other researchers. The results show that the pressure drop depends significantly on the gas flow rate and that water flow rate does not have significant effects neither on the pressure drop nor on the fluid maximum velocity within the scrubber.

Adiabatic Horizontal and Vertical Pressure Drop of Carbon Dioxide Inside Smooth and Microfin Tubes at Low Temperatures

2008 ◽  
Vol 130 (11) ◽  
Author(s):  
Yoon Jo Kim ◽  
Jeremy Jang ◽  
Predrag S. Hrnjak ◽  
Min Soo Kim
Keyword(s):  
Pressure Drop ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Interfacial Shear Stress ◽  
Smooth Tube ◽  
Phase Flow ◽  
Two Phase ◽  
Vertical Pressure ◽  
Frictional Pressure Drop ◽  
Microfin Tubes

This paper presents the pressure drop data and the analysis of adiabatic CO2 flow in horizontal and vertical smooth and microfin tubes at saturation temperatures around −20°C. The test tubes had 3.48mm inner diameter smooth tube and a 3.51mm melt-down diameter microfin tube. The test was performed over a mass flux range of 200–800kg∕m2s and at saturation temperatures of −25°C and −15°C. The effects of various parameters—mass flux, saturated temperature, and tube diameter—on pressure drop were qualitatively analyzed. The analyses showed that the frictional pressure drop characteristics of vertical two-phase flow were much different from that of the horizontal two-phase flow. The microfin tube can be considered as “very rough tube” having the roughness of “fin height.” The data were compared with several correlations. The existing frictional pressure drop correlation is sufficient to predict the horizontal pressure drop in smooth tube. For the vertical pressure drop, the simple combination of the frictional pressure drop and void fraction model was in comparatively good agreement. However, the qualitative results showed that there were some limits to cover the different mechanisms related to the interfacial shear stress. The average enhancement factors and penalty factors evidenced that it was not always true that the internally finned geometry guaranteed the superior in-tube condensation performance of microfin tube in refrigeration system and air-conditioning systems.

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