NUMERICAL INVESTIGATION OF TURBULENT MODELS IN THE DEVELOPMENT AND ESTABLISHMENT OF TURBULENT FLOWS WITH FLOW CONDITIONERS

ABSTRACT The accuracy in measuring flow of fluids such as gas and oil has a great importance for the Algerian economy. The flows of fluids in non-standard conditions, presence of disturbances, in which there are flow meters in pipes, make a very important error. International standards ISO 5167 and AGA3 stipulate that the meter is installed in a fully developed flow. This article describes a numerical investigation of development and establishment of flows in the presence of a double bend 90° in perpendicular planes as a perturbation. The software used was code Fluent where different turbulence models are tested to better simulate and view the effectiveness of models in the description of the flow of fluid compared to flow behaviour cited in the standards and the experimental results. The numerical experimentation is done with air in a pipe of 100mm diameter at a Reynolds number 10 5 . The numerical analysis is based on solving Navier-Stokes equation system with several turbulent models, k-, k-ω, RSM and its variants. INTRODUCTION The majority of the industrial flowmeters are gauged under conditions of perfectly established flow. This condition is actually very difficult to respect, being given the presence of the components of the system of control which are essential to its exploitation. So the presence of singularities such as, valve, elbow… etc, obviously constitute a source of error in the measurement of the flo

Concentrations and sources of Cd, Cr, Cu, Fe, Ni, Pb and Zn in soil of the Mitidja plain, Algeria

peer reviewedIn the last few decades, the Mitidja plain has undergone economic development which may have altered the concentrations of some trace metals in its soils. Therefore, this study was aimed at investigating the concentrations and sources of Cd, Cr, Cu, Fe, Ni, Pb and Zn in 180 composite topsoil samples using a combination of environmental quality indicators and multivariate statistical approaches with a geographic information system (GIS). Based on spatial distribution maps, various hot-spots have been identified. Enrichment factors (EFs) indicated that Cd, Cu, Pb and Zn were from anthropogenic sources, while Ni and Cr were controlled mainly by natural lithogenic source. Multivariate statistical analyses were in agreement, except for Cu which was classified as coming from both anthropogenic and lithogenic sources. © 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group

Numerical investigation of contribution of three flow conditioners in the development and establishment of turbulent flows

ABSTRACT This numerical study is a comparative study of the development and establishment of turbulent flows through three flow conditioners namely Laws perforated plate, the Etoile and the tube bundle. They are installed in a circular pipe with a disturbance generated by a 90° double bend out of plane which causes a very strong swirl of the fluid. The analysis is done with the code Fluent in which the Navier-Stokes equations describe a three-dimensional incompressible flow with the Reynolds stress model (RSM) as a closure system. This article focuses on the effectiveness of the three packers to produce the condition of fully developed velocity profile. The results are compared to references profiles cited in the literature and experimental results. The flow is simulated with air at Reynolds number of 10 5 in 100mm pipe diameter. The velocity profiles are compared with the profile obtained by the universal law of power 1/7 th

Numerical analysis of the discharge coefficient with disturbers for flowmetring accuracy

The present work concerns a numerical investigation of the effect of orifice meter diameters on the discharge coefficient for flow measurement purpose. The flow is subject to two disturbers namely a 90° double bend in perpendicular planes and a 50% closed valve. The turbulent flow is examined in conduit with an inner diameter of D=100mm. The diameter of orifice meters are respectively d=40, 50, 60, 70 and 75mm which done for β ratio d/D respectively the values of 0.4, 0.5, 0.6, 0.7 and 0.75. The orifice meters are located in conduit at different stations downstream the disturbers. The flow is examined with air at Reynolds number Re=2.5x105. The software used for this simulation is CFD code Fluent with k-ε like turbulence model. As a conclusion, the analysis of numerical results shows that when the diameter of the orifice meter increases the shifts deviation in the discharge coefficient increases this causes a great error in flow measurement. Contrary, when the diameter of the orifice meter decreases the shifts deviation in the discharge coefficient decreases and the errors in flow measurement is reduced. These results are the same with the two disturbers used separately in conduit

Evaluation de la qualité environmentale des sols de la plaine de la Mitidja, Algérie

The present study investigates the soil environmental quality from Mitidja plain using pollution index and pollution load index. A total of 180 composite topsoil samples were collected and analyzed for Cd, Cr, Cu, Fe, Ni, Pb and Zn. The results showed that soils samples were uncontaminated with Cr and Ni, and moderately contaminated with Cu, Cd, Pb and Zn. According to the spatial distribution map of pollution load index, 17% of the whole studied area was belonged to low contamination, while 70% and 13% were moderately and highly contaminated with trace metals, respectively. Overall, the studied area is classified as moderately contaminated. The highest levels of contamination have been observed near urban and industrial areas. The main sources of contamination appear to be related to traffic emissions, atmospheric deposition of particles, and wastes discharge. The results of this study can help the decision makers to implement suitable control measures.15. Life on lan

Identification of Open-Circuit Faults in T-Type Inverters Using Fuzzy Logic Approach

With the increasing adoption of solar Pho- tovoltaic (PV) systems in several applications, reliabil- ity and service continuity are important challenges that need to be addressed. Power converters are vital com- ponents in solar PV systems and inverters tend to be the most likely devices of equipment to experience faults which usually occur in the switching devices. It is there- fore critical to assess the functioning of the inverters and identify these faults in order to lower risks and the resulting financial losses. Open-circuit faults (OCF) are among the most common. This paper suggests a fuzzy-based fault detection approach for the T-Type in- verter in grid connected PV system based on the diag- nosis variables which are calculated using the average values of positive and the negative parts of the normal- ized output currents data. After that, these variables are analyzed using a fuzzy logic technique, The single, multiple power switch open circuit faults may all be de- tected and diagnosed utilizing this fuzzy-based fault di- agnostic technique. The results of the simulation in MATLAB show that the proposed method can accu- rately identify and locate OCF the inverter switches

Ambient background and quality reference values for trace metals in soils from Algeria

peer reviewedThe establishment of the reference ambient background concentrations (ABCs) and quality reference values (QRVs) for trace metal (TM) concentrations in soils are required for the environmental assessment and any implementation of a protective action. This information is lacking for soils of the eastern Mitidja plain, which is an important agricultural production area in Algeria. Data for the aqua regia extractable Cd, Cr, Cu, Fe, Ni, Pb and Zn concentrations from 180 composite topsoil samples taken across the Mitidja plain in a stratified random pattern were statistically analysed. Descriptive statistical methods and linear regression equations were applied to determine the upper limit of the ABCs for the TMs. After removal of outliers, the derived QRVs were: Cd 0.24, Cr 62.1, Cu 99.3, Fe 45 590, Ni 47.7, Pb 33 and Zn 115 mg/kg. Iron is a macro element in the soils, but is included as its concentration can be used to normalise the concentrations of the other elements. The derived QRVs are similar or less than those reported for other regions of the world, apart from Cu, where a wide range (36 to 206 mg/kg) is reported. These reference values can be used to identify areas that may require follow-up surveys or to identify priority sites for decision making