scholarly journals Numerical Simulation and Experimental Validation of an Oil Free Scroll Compressor

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5863
Author(s):  
Massimo Cardone ◽  
Bonaventura Gargiulo
Keyword(s):  
Experimental Data ◽  
Experimental Validation ◽  
Test Bench ◽  
Outlet Temperature ◽  
Analysis Software ◽  
Scroll Compressor ◽  
One Dimensional ◽  
Geometrical Features ◽  
The One ◽  
Semi Empirical

This paper presents a virtual model of a scroll compressor developed on the one-dimensional analysis software Simcenter Amesim®. The model is semi-empirical: it needs some physical details of the modelled machine (e.g., the cubic capacity), but, on the other hand, it does not require the geometrical features of the spirals, so it needs experimental data to calibrate it. The model also requires rotational speed and the outlet temperature as boundary conditions. The model predicts the power consumption and the mass flow rate and considers leakages and mechanical losses. After the model presentation, this paper describes the test bench and the obtained data used to calibrate and validate the model. At last, the calibration process is described, and the results are discussed. The calculated values fit the experimental data also in extrapolation, despite the model is simple and performs calculations within 7 s. Due to these characteristics, the model is suitable for being used in a larger model as a sub-component.

Two-Fluid CFD Model of Adiabatic Air-Water Upward Bubbly Flow Through a Vertical Pipe With a One-Group Interfacial Area Transport Equation

2009 ◽  
Author(s):  
Deoras Prabhudharwadkar ◽  
Chris Bailey ◽  
Martin Lopez de Bertodano ◽  
John R. Buchanan
Keyword(s):  
Experimental Data ◽  
Transport Equation ◽  
Bubbly Flow ◽  
Interfacial Area ◽  
Correct Prediction ◽  
Interfacial Area Transport ◽  
One Dimensional ◽  
Interfacial Area Transport Equation ◽  
The One ◽  
Two Fluid

This paper describes in detail the assessment of the CFD code CFX to predict adiabatic liquid-gas two-phase bubbly flow. This study has been divided into two parts. In the first exercise, the effect of Lift Force, Wall Force and the Turbulent Diffusion Force have been assessed using experimental data from the literature for air-water upward bubbly flows through a pipe. The data used here had a characteristic near wall void peaking which was largely influenced by the joint action of the three forces mentioned above. The simulations were performed with constant bubble diameter assuming no bubble interactions. This exercise resulted in selection of the most appropriate closure form and closure coefficients for the above mentioned forces for the range of flow conditions chosen. In the second exercise, the One-Group Interfacial Area Transport equation was introduced in the two-fluid model of CFX. The interfacial area density plays important role in the correct prediction of interfacial mass, momentum and energy transfer and is affected by bubble breakup and coalescence processes in adiabatic flows. The One-Group Interfacial Area Transport Equation (IATE) has been developed and implemented for one-dimensional models and validated using cross-sectional area averaged experimental data over the last decade by various researchers. The original one-dimensional model has been extended to multidimensional flow predictions in this study and the results are presented in this paper. The paper also discusses constraints posed by the commercial CFD code CFX and the solutions worked out to obtain the most accurate implementation of the model.

scholarly journals Assessment of CFD turbulence models for free surface flow simulation and 1-D modelling for water level calculations over a broad-crested weir floodway

Water SA ◽  
2019 ◽  
Vol 45 (3 July) ◽  
Author(s):  
Ahmed M Helmi
Keyword(s):  
Experimental Data ◽  
Free Surface ◽  
Water Level ◽  
Dimensional Analysis ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Cfd Simulations ◽  
One Dimensional ◽  
The Mean ◽  
The One

Floodways, where a road embankment is permitted to be overtopped by flood water, are usually designed as broad-crested weirs. Determination of the water level above the floodway is crucial and related to road safety. Hydraulic performance of floodways can be assessed numerically using 1-D modelling or 3-D simulation using computational fluid dynamics (CFD) packages. Turbulence modelling is one of the key elements in CFD simulations. A wide variety of turbulence models are utilized in CFD packages; in order to identify the most relevant turbulence model for the case in question, 96 3-D CFD simulations were conducted using Flow-3D package, for 24 broad-crested weir configurations selected based on experimental data from a previous study. Four turbulence models (one-equation, k-ε, RNG k-ε, and k-ω) ere examined for each configuration. The volume of fluid (VOF) algorithm was adopted for free water surface determination. In addition, 24 1-D simulations using HEC-RAS-1-D were conducted for comparison with CFD results and experimental data. Validation of the simulated water free surface profiles versus the experimental measurements was carried out by the evaluation of the mean absolute error, the mean relative error percentage, and the root mean square error. It was concluded that the minimum error in simulating the full upstream to downstream free surface profile is achieved by using one-equation turbulence model with mixing length equal to 7% of the smallest domain dimension. Nevertheless, for the broad-crested weir upstream section, no significant difference in accuracy was found between all turbulence models and the one-dimensional analysis results, due to the low turbulence intensity at this part. For engineering design purposes, in which the water level is the main concern at the location of the flood way, the one-dimensional analysis has sufficient accuracy to determine the water level.

First bent form for the hydroxo-bridged cis-diammineplatinum(II) dimer [Pt2(NH3)4(μ-OH)2](ClO4)2

2004 ◽  
Vol 60 (3) ◽  
pp. 255-262 ◽  
Author(s):  
Ken Sakai ◽  
Yosuke Konno ◽  
Noboru Takayama ◽  
Satoru Takahashi
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Planar Geometry ◽  
One Dimensional ◽  
The Third ◽  
Geometrical Features ◽  
Hydrogen Bonding Network ◽  
The One ◽  
Carbonate Salts ◽  
Perchlorate Salt

The third crystal structure containing the hydroxo-bridged cis-diammineplatinum(II) dimer has been determined for a perchlorate salt of the complex, [Pt2(NH3)4(μ-OH)2](ClO4)2. However, the dinuclear cations in the nitrate and the carbonate salts, [Pt2(NH3)4(μ-OH)2](NO3)2 [Faggiani, Lippert, Lock & Rosenberg (1977). J. Am. Chem. Soc. 99, 777–781] and [Pt2(NH3)4(μ-OH)2](CO3)·H2O [Lippert, Lock, Rosenberg & Zvagulis (1978). Inorg. Chem. 17, 2971−2975], were reported to possess a nearly planar geometry. The cation in the title perchlorate salt has been found to possess an exceptional bent form in which two Pt coordination planes within the dimer are tilted at an angle of 151.7 (1)° to one another. The diplatinum entity has a syn orientation with regard to the conformation of two hydroxo bridges, in part due to the one-dimensional hydrogen-bonding network achieved in the crystal structure. DFT MO investigations have also been carried out to reveal that the planar-bent selection could be induced by the anti–syn selection at the H(hydroxo) atoms. Comparison has also been made between the geometrical features of the three salts from the viewpoint of the orientation of H(hydroxo) atoms.

scholarly journals Radial Imbibition in Paper under Temperature Differences

Fluids ◽  
2019 ◽  
Vol 4 (2) ◽  
pp. 86
Author(s):  
Abel López-Villa ◽  
Abraham Medina ◽  
F. J. Higuera ◽  
Jonatan R. Mac Intyre ◽  
Carlos Alberto Perazzo ◽  
...  
Keyword(s):  
Experimental Data ◽  
Surface Tension ◽  
Porous Material ◽  
Radial Temperature ◽  
Temperature Variations ◽  
One Dimensional ◽  
Blotting Paper ◽  
Dimensional Equation ◽  
The One ◽  
Account Temperature

Spontaneous radial imbibition into thin circular samples of porous material when they have been subjected to radial temperature differences was analyzed theoretically and experimentally. The use of the Darcy equation allowed us to take into account temperature variations in the dynamic viscosity and surface tension in order to find the one-dimensional equation for the imbibition fronts. Experiments using blotting paper showed a good fit between the experimental data and theoretical profiles through the estimation of a single parameter.

Numerical Solution for Two-Dimensional Elastic Wave Propagation in Finite Bars

1967 ◽  
Vol 34 (3) ◽  
pp. 725-734 ◽  
Author(s):  
L. D. Bertholf
Keyword(s):  
Experimental Data ◽  
Wave Propagation ◽  
Elastic Wave ◽  
Numerical Solutions ◽  
Step Change ◽  
Two Dimensional ◽  
One Dimensional ◽  
Elastic Bar ◽  
The One ◽  
The Impact

Numerical solutions of the exact equations for axisymmetric wave propagation are obtained with continuous and discontinuous loadings at the impact end of an elastic bar. The solution for a step change in stress agrees with experimental data near the end of the bar and exhibits a region that agrees with the one-dimensional strain approximation. The solution for an applied harmonic displacement closely approaches the Pochhammer-Chree solution at distances removed from the point of application. Reflections from free and rigid-lubricated ends are studied. The solutions after reflection are compared with the elementary one-dimensional stress approximation.

The Simulation of Photocatalysis Degradation of Formaldehyde Using Nano-TiO2 Based on the Diffusion Model

2013 ◽  
Vol 327 ◽  
pp. 8-12
Author(s):  
Bin Li ◽  
Kai Xiao Zhang ◽  
Chao Yu Feng ◽  
Xing Bin Zheng ◽  
Kun Xie ◽  
...  
Keyword(s):  
Experimental Data ◽  
Photocatalytic Degradation ◽  
Diffusion Model ◽  
Degradation Rate ◽  
Nano Tio2 ◽  
Fick's Law ◽  
One Dimensional ◽  
Photocatalytic Mechanism ◽  
Dimensional Diffusion ◽  
The One

In this paper, the one-dimensional diffusion model about nano-TiO2 photocatalytic degradation of formaldehyde process was established ,through analyzing nano-TiO2 photocatalytic mechanism, and verifying the accuracy of the model by the experimental data combined with Fick's law. According to this model, it concluded that the degradation rate of the formaldehyde is related to the height of purification apparatus, and when the height is smaller, the degradation rate is greater. Within the same cleaning time (t = 200min), when the height is 0.15m, the rate of degradation of formaldehyde is 99%; when the height is 0.3m, the rate of degradation of formaldehyde is 88%; while the height is 0.7m , the rate is only 32%.

Prediction of the One-Dimensional Equilibrium Cutting Gap in Electrochemical Machining

1969 ◽  
Vol 91 (3) ◽  
pp. 755-763 ◽  
Author(s):  
J. Hopenfeld ◽  
R. R. Cole
Keyword(s):  
Experimental Data ◽  
Nonlinear Differential Equations ◽  
Electrochemical Machining ◽  
Local Variation ◽  
Two Phase ◽  
One Dimensional ◽  
Proper Design ◽  
Electrolyte Mixture ◽  
The One ◽  
State Case

In electrochemical machining the evolution of gas and heat in the electrolyte results in local variation of the gap between the electrodes. The ability to predict these variations for any given operating condition is a prerequisite of proper design of the cathode tool. This paper provides analytical predictions of the change in gap geometry for the one-dimensional steady-state case. Employing the basic conservation laws, a system of coupled nonlinear differential equations is derived for the gas-electrolyte mixture which flows between the electrodes. The assumption of homogeneity of the two-phase mixture is employed throughout the analysis. Numerical results from the solution of the equations are presented graphically and compared with experimental data. The local variation in gap and the relation between current, gap, and applied voltage compare favorably with the experimental data within the ranges of parameters investigated: current density 45–400 amps per sq in., electrolyte flow rate 0.22–0.98 gpm, entrance gap size 0.015–0.020 in., potassium chloride electrolyte normality 0.67–1.14.

scholarly journals Flow Simulation in a combined Region

2021 ◽  
Vol 264 ◽  
pp. 01016
Author(s):  
Umurdin Dalabaev
Keyword(s):  
Experimental Data ◽  
Porous Medium ◽  
Flow Simulation ◽  
Two Dimensional ◽  
Dimensional Problem ◽  
Heterogeneous Model ◽  
One Dimensional ◽  
Free Zone ◽  
Porous Framework ◽  
The One

The article deals with the flow in a complex area. The composition of this region consists of a porous medium through the pores of which the liquid moves and a zone without a porous framework (free zone). The flow is modeled using an interpenetrating heterogeneous model. In the one-dimensional case, an analytical solution is obtained. This solution is compared with the solution learned by the move node method. An analysis is made with experimental data with a Brinkman layer. A numerical solution of a two-dimensional problem is also obtained.

scholarly journals Simulations of autonomous fluid pulses between active elastic walls using the 1D-IRBFN method

2018 ◽  
Vol 13 (5) ◽  
pp. 47 ◽  
Author(s):  
Fatima Z. Ahmed ◽  
Mayada G. Mohammed ◽  
Dmitry V. Strunin ◽  
Duc Ngo-Cong
Keyword(s):  
Numerical Solutions ◽  
Initial Conditions ◽  
Radial Basis Function Network ◽  
Active Motion ◽  
One Dimensional ◽  
Pulse Trains ◽  
The One ◽  
Semi Empirical ◽  
Function Network ◽  
Elastic Walls

We present numerical solutions of the semi-empirical model of self-propagating fluid pulses (auto-pulses) through the channel simulating an artificial artery. The key mechanism behind the model is the active motion of the walls in line with the earlier model of Roberts. Our model is autonomous, nonlinear and is based on the partial differential equation describing the displacement of the wall in time and along the channel. A theoretical plane configuration is adopted for the walls at rest. For solving the equation we used the One-dimensional Integrated Radial Basis Function Network (1D-IRBFN) method. We demonstrated that different initial conditions always lead to the settling of pulse trains where an individual pulse has certain speed and amplitude controlled by the governing equation. A variety of pulse solutions is obtained using homogeneous and periodic boundary conditions. The dynamics of one, two, and three pulses per period are explored. The fluid mass flux due to the pulses is calculated.

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