Operation technological process research in the cleaning system of the grain combine

The purpose of this study is to increase the efficiency of the technological process of a combine harvester cleaning system. It involved the simulation of the actual work process, the identification of problem areas and the uniform airflow distribution across the width of the sieve mill. The method for determining the class of ‘air-grain heap’ flow in the combine harvester cleaning system is presented in order to provide the mathematical description of its technical work process. As a result, the volumetric (Q = 8·10–6 ÷ 2.5·10–4) and mass (W = 0.01 ÷ 0.3) concentration of a grain heap in different sections of the sieve mill of the combine harvester cleaning system. The experimental measurements of the airflow speed on the sieve mill’s surface for the existing structures of the cleaning system in modern grain harvesters were 3.75 ÷ 10.2 m/s. The data obtained will be used in the future to implement a mathematical model for a complete description of the technological process of a combine harvester cleaning system using methods based on two-phase flow mechanics.

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Experimental Measurements and Numerical Simulations of Two-Phase Stratified, Wavy and Slug Flow in a Narrow Rectangular Channel

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2005-77091 ◽

2005 ◽

Author(s):

Steven P. O’Halloran ◽

B. Terry Beck ◽

Mohammad H. Hosni ◽

Steven J. Eckels

Keyword(s):

Numerical Simulations ◽

Slug Flow ◽

Two Phase Flow ◽

Rectangular Channel ◽

Measurement Techniques ◽

Narrow Channel ◽

Experimental Measurements ◽

Phase Flow ◽

Two Phase ◽

Two Fluids

Flow pattern transitions in two-phase flow are important phenomena for many different types of engineering applications, including heat exchangers. While two-phase flow is not understood as well as single-phase flow, advancements in both measurement techniques and numerical simulations are helping to increase the understanding of two-phase flow. In this paper, stratified/wavy flow is investigated, along with the transition from wavy to slug flow. For the experimental setup, a narrow channel with a length of 600 mm, height of 40 mm, and a width of 15 mm was fabricated using clear acrylic plastic, and water and air were the two fluids used for testing. The water in the channel was initially at rest, and the transition in flow patterns was created by increasing the velocity of air flowing over the water surface. Particle image velocimetry (PIV) was used to measure the velocity of the flow for stratified and wavy flow conditions, and also the velocity at the onset of slug flow. Along with the experimental measurements, computational fluid dynamics (CFD) simulations were conducted on a similar geometry using the volume of fluid (VOF) two-phase model. A commercial CFD software package was used for the simulations, and comparisons were made between the experimental measurements and numerical results. Favorable agreement was found between the experimental measurements and the numerical simulations. In particular, the transition from wavy to slug flow compared well to previously developed two-phase flow transition models, including the slug transition developed by Taitel and Dukler.

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Investigating the Characteristics of Two-Phase Flow Using Electrical Capacitance Tomography (ECT) for Three Pipe Orientations

Processes ◽

10.3390/pr8010051 ◽

2020 ◽

Vol 8 (1) ◽

pp. 51 ◽

Cited By ~ 6

Author(s):

Zeyad Almutairi ◽

Fayez M. Al-Alweet ◽

Yusif A. Alghamdi ◽

Omar A. Almisned ◽

Othman Y. Alothman

Keyword(s):

High Speed ◽

Two Phase Flow ◽

Flow Patterns ◽

Electrical Capacitance Tomography ◽

Experimental Measurements ◽

Phase Flow ◽

Electrical Capacitance ◽

Liquid Holdup ◽

Two Phase ◽

Capacitance Tomography

Experiments of gas–liquid flow in a circular pipe for horizontal and inclined positions (upward/downward) are reported. The characteristics of two-phase flow in terms of liquid holdup (ε(L)) and induced flow patterns are studied using three experimental techniques; time-averaged ε(L) from permittivity profiles using electrical capacitance tomography (ECT), instantaneous ε(L) using two fast-closing valves (TFCV), and high-speed camera images (HSCI) to capture/identify the formed flow patterns. Thus, this experimental setup enables the development of more well-defined flow patterns in gas–liquid two-phase flow and allows for multi-technique verification of the results. Taken from experimental measurements, a model is proposed to predict ε(L) for high and low situations. The correlations are a function of the hydrodynamic dimensionless quantities which provide hydrodynamic similarity. Regarding different pipe orientations, ε(L) predictions are comparable to ε(L) from experimental measurements with accepted accuracy: 88% of the predictions are within ±5–15% and 98% are below ±20%. The correlations also were validated by reported results and against correlations available in the literature and show higher prediction accuracy. It is confirmed that the kinematic similarity which is achieved by the gas–liquid velocity ratios and the inertial forces influence the flow pattern and the liquid holdup.

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Analytical and Experimental Investigation of Two-Phase Flow Screw Expanders for Power Generation

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.3240182 ◽

1988 ◽

Vol 110 (4) ◽

pp. 628-635 ◽

Cited By ~ 29

Author(s):

H. Taniguchi ◽

K. Kudo ◽

W. H. Giedt ◽

I. Park ◽

S. Kumazawa

Keyword(s):

Power Generation ◽

Experimental Investigation ◽

Analytical Procedure ◽

Two Phase Flow ◽

Experimental Measurements ◽

Phase Flow ◽

Rotor Speed ◽

Two Phase ◽

Speed Range ◽

Experimental Values

An analytical procedure for calculating the performance of a two-phase flow screw-type expander is presented. Predicted results are compared with experimental measurements made with a recently developed prototype expander. This expander was designed for investigating the applicability of this type of machine as the expansion device in refrigeration or heat pump cycles with the objective of taking advantage of the power-producing capability of the expanding fluid. It has two rotors each with a diameter of 81.6 mm and a length of 135 mm, and was operated with Freon-12 entering at a pressure of 1.588 MPa (230.4 psia) and subcooling of between 2 and 12 K. Maximum power generated was 10 kW at a rotor speed of 3000 rpm. The internal (machine) efficiency is predicted to increase from about 30 to 70 percent as the rotor speed increases from 500 to 3000 rpm. Experimental results over this same speed range increase from 30 to 60 percent. The lower experimental values at the higher rotor speeds are attributed primarily to frictional losses not included in the analysis. Estimates of the performance of machines with larger diameter rotors yielded internal efficiencies reaching 80 percent and increases in power output proportional to the square of the rotor diameter.

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Numerical and Experimental Study of Polydispersed Acetone Spray Dispersion and Evaporation in Turbulent Flow

Volume 2: Combustion, Fuels and Emissions, Parts A and B ◽

10.1115/gt2011-46301 ◽

2011 ◽

Author(s):

M. Chrigui ◽

A. Sadiki ◽

J. Gounder ◽

A. Masri

Keyword(s):

Turbulent Flow ◽

Carrier Phase ◽

Two Phase Flow ◽

Stokes Equations ◽

Vapor Concentration ◽

Experimental Measurements ◽

Phase Flow ◽

Two Phase ◽

Radial Profiles ◽

Wide Range

Characteristics of acetone spray in a turbulent flow were numerically predicted and compared to experimental measurements. The focus was on the effect of polydispersity on the dispersion and evaporation of a relatively volatile fuel that featured a wide range of Stokes numbers in a turbulent two phase flow. Droplets were generated using an ultrasonic atomizer. It produced a relatively uniform velocity distribution with a moderate carrier to fuel velocities ratio. The simulations were performed in the framework of Reynolds Averaging Navier Stokes equations along with the Eulerian-Lagrangian approach where 12 different classes of the dispersed phase were tracked. Droplets differed in diameter, mean and rms velocities, and numbers density. The transport equations of the carrier phase were formulated in an Eulerian reference frame that included terms which accounted for the exchange of mass, momentum, energy and turbulence quantities with the spray, i.e. fully two way coupling. The phase transition was modeled by the Langmuir-Knudsen law that accounted for non equilibrium effects based on a consistent determination of the molar mass fraction on the droplet surfaces. Effects of turbulence modulation on the vaporization processes were resolved by a thermodynamically consistent model that determined the turbulence intensity at the droplet location, which affected the vapor concentration gradient near the droplet surfaces. For the droplet diffusion, the Markov sequence model was improved by adding a correction drift term to the fluid fluctuation velocity at the parcel position along the droplet trajectory. This correction term aimed at accounting for the non-homogeneity effects in the turbulent flow. The different sub-models for the prediction of multiphase flow characteristics were applied to a 3D configuration that consisted of a spray nozzle mounted in a 4 m/s coflowing air stream. A number of carrier phase jet velocities were used, thus denoting a variation of the fuel to air mass loading. Radial profiles of the axial and radial velocities and its corresponding rms fluctuations of the acetone spray were predicted and compared to the experimental measurements. Spray mass flux, which determined the degree of evaporation, was plotted at different axial location from the nozzle exit plane. The study aimed at assessing the combination of different models applied to a mono-component spray for the prediction of two-phase flow and at investigating what should be improved for the case of real fuel (eg. Kerosene) for industrial configurations.

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Optimization of FPD Cleaning System and Processing by Using a Two-Phase Flow Nozzle

Korean Journal of Materials Research ◽

10.3740/mrsk.2014.24.8.429 ◽

2014 ◽

Vol 24 (8) ◽

pp. 429-433

Author(s):

Min-Su Kim ◽

Hyang-Ran Kim ◽

Hyun-Tae Kim ◽

Jin-Goo Park

Keyword(s):

Two Phase Flow ◽

Phase Flow ◽

Two Phase ◽

Cleaning System

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Water exit dynamics of jumping archer fish: Integrating two-phase flow large-eddy simulation with experimental measurements

Physics of Fluids ◽

10.1063/1.5130886 ◽

2020 ◽

Vol 32 (1) ◽

pp. 011904 ◽

Cited By ~ 6

Author(s):

Ali Khosronejad ◽

Leah Mendelson ◽

Alexandra H. Techet ◽

Dionysios Angelidis ◽

Fotis Sotiropoulos

Keyword(s):

Large Eddy Simulation ◽

Two Phase Flow ◽

Experimental Measurements ◽

Phase Flow ◽

Two Phase ◽

Eddy Simulation ◽

Large Eddy ◽

Water Exit

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A Comparison of VOF and Euler-Euler Approaches in CFD Modelling of Two-Phase Flows With a Sharp Interface

Volume 2C: Turbomachinery ◽

10.1115/gt2020-14681 ◽

2020 ◽

Author(s):

Luc Bertolotti ◽

Richard Jefferson-Loveday ◽

Stephen Ambrose ◽

Evgenia Korsukova

Keyword(s):

Shear Flows ◽

Two Phase Flow ◽

Thickness Distribution ◽

Volume Of Fluid ◽

Sharp Interface ◽

Experimental Measurements ◽

Phase Flow ◽

Two Phase Flows ◽

Two Phase ◽

Two Phases

Abstract In aero-engines, it is important to predict the behavior of shear flows in the different parts such as bearing chambers or gearboxes. In bearing chambers, the thickness distribution of wavy films is well studied as two-phase flows are still very hard to predict depending on the case. Experimental studies remain very expensive to carry out and Computational Fluid Dynamics (CFD) still struggles with two-phase flow prediction especially when a sharp interface between the two phases must be modelled. CFD is used to predict the oil film thickness distribution and interface velocity at different engine operating conditions. Currently Reynold-Averaged Navier-Stokes (RANS) CFD uses a semi-empirical method of turbulence damping, which is inaccurate for wavy films and so impacts the modelling of bearing chambers and gearboxes. With the objective of improving RANS models from Large Eddy Simulation (LES) methods, the Volume of Fluid (VOF) and Euler-Euler methods for two-phase flow modelling are investigated in this study. The Volume of Fluid (VOF) approach assumes a single set of momentum equations for the two phases and volume fractions are 1 or 0 everywhere except in the interface region. An alternative to VOF, is the Euler-Euler method with interface sharpening for shear flows. This approach assumes one set of momentum equations per phase but a shared field of pressure. The VOF and Euler-Euler approaches are compared in this study using LES with the CFD code OpenFOAM v6. The case study is based on experimental work investigating stratified flow in a horizontal channel that will be further detailed in the paper. In this study, a simplified 3D periodic channel filled with two distinct phases: air and water is used. A flow regime is studied in which flows are fully developed and the water phase has a much smaller velocity than the air phase in order to obtain a shear flow. Numerical results are compared with experimental measurements from the literature. With OpenFOAM, the VOF solver used for the study is interFoam and the Euler-Euler solver used is reacting-MultiphaseEulerFoam. Velocity profiles, shear-stress profiles and kinetic energy profiles are compared with experimental measurements for the assessment of the two flow solvers. Maps of vorticity magnitude are also provided to support the comparisons between the Euler-Euler and the VOF approaches as well as an appropriate vortex identification method.

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