A Parametric Computational Fluid Dynamics Analysis of the Valve Pocket Losses in Reciprocating Compressors

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Francesco Balduzzi ◽  
Giovanni Ferrara ◽  
Riccardo Maleci ◽  
Alberto Babbini ◽  
Guido Pratelli
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Response Surface ◽  
Cfd Simulation ◽  
Flow Coefficient ◽  
Reciprocating Compressor ◽  
Pressure Losses ◽  
Computational Fluid Dynamics Analysis ◽  
Efficiency Increase ◽  
Analytical Response

The reduction of pressure losses is one of the most important challenges for the efficiency increase of a reciprocating compressor. Since the absorbed power is strongly affected by the losses through pocket valves and cylinder ducts, an accurate prediction of these losses is essential. The use of computational fluid dynamics (CFD) simulation has shown great potential for the study of the entire reciprocating compressor, but is still limited by high computational costs. Recently, the authors have presented a simplified CFD approach: the actual valve geometry is replaced with an equivalent porous region, which has significantly increased the speed of calculation while ensuring accuracy as well. Based on this approach, a new methodology for the evaluation of pocket valve losses is presented. A set of CFD simulations using a parameterized geometry of the pocket valve was performed to evaluate the relationship between the losses of the pocket and its geometrical features. An analytical response surface (RS) was defined using the values of the geometrical dimensions as inputs and the pocket flow coefficient as output. Finally, the response surface was validated through a set of test cases performed on different geometries with the actual valve and the results have shown good predictability of the tool.

A Parametric CFD Analysis of the Valve Pocket Losses in Reciprocating Compressors

2013 ◽  
Author(s):  
Francesco Balduzzi ◽  
Giovanni Ferrara ◽  
Riccardo Maleci ◽  
Alberto Babbini ◽  
Guido Pratelli
Keyword(s):  
Response Surface ◽  
High Efficiency ◽  
Cfd Simulation ◽  
Accurate Estimate ◽  
Flow Coefficient ◽  
Pressure Losses ◽  
Geometrical Features ◽  
Analytical Response ◽  
Absorbed Power ◽  
Increasing Demand

The increasing demand for high efficiency in the field of energy production has also had an impact on reciprocating compressors. In this case, the need to reduce losses is one of the most important challenges. In the past, most studies were focused only on the analysis of valve pressure losses. More recently, interest has been extended to the prediction of the losses through pocket valves and cylinder ducts, these losses being a crucial aspect of a more accurate estimate of the absorbed power. The use of CFD simulation has shown great potential for the study of the entire reciprocating compressor, but is still limited by high computational costs. Recently the authors have presented a simplified CFD approach: the actual valve geometry is replaced with an equivalent porous region, which has significantly increased the speed of calculation while ensuring accuracy as well. Based on this approach, a new methodology for the evaluation of pocket valve losses is presented. Since the pocket losses have been proven to be independent of the actual valve installed, a set of CFD simulations using a parameterized geometry of the pocket valve was performed and the relationship between the losses of the pocket and its geometrical features was obtained. An analytical response surface was defined using the values of the geometrical dimensions as inputs and the pocket flow coefficient as output. Finally, the response surface was validated through a set of test cases performed on different geometries with the actual valve and the results have shown good predictability of the tool.

Computational fluid dynamics analysis of a modified Savonius rotor and optimization using response surface methodology

2017 ◽  
Vol 41 (5) ◽  
pp. 285-296 ◽  
Author(s):  
Haris Moazam Sheikh ◽  
Zeeshan Shabbir ◽  
Hassan Ahmed ◽  
Muhammad Hamza Waseem ◽  
Muhammad Zubair Sheikh
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Response Surface Methodology ◽  
Response Surface ◽  
Design Of Experiment ◽  
Coefficient Of Performance ◽  
Speed Ratio ◽  
Ansys Fluent ◽  
Computational Fluid Dynamics Analysis ◽  
Parametric Effects

This article aims to present a two-dimensional parametric analysis of a modified Savonius wind turbine using computational fluid dynamics. The effects of three independent parameters of the rotor, namely, shape factor, overlap ratio, and tip speed ratio on turbine performance were studied and then optimized for maximum coefficient of performance using response surface methodology. The rotor performance was analyzed over specific domains of the parameters under study, and three-variable Box-Behnken design was used for design of experiment. The specific parametric combinations as per design of experiment were simulated using ANSYS Fluent®, and the response variable, coefficient of performance (Cp), was calculated. The sliding mesh model was utilized, and the flow was simulated using Shear Stress Transport (SST) k − ω model. The model was validated using past experimental results and found to predict parametric effects accurately. Minitab® and ReliaSoft DOE++® were used to develop regression equation and find the optimum combination of parameters for coefficient of performance over the specified parametric domains using response surface methodology.

CFD Evaluation of the Pressure Losses in a Reciprocating Compressor: A Flexible Approach

2012 ◽  
Author(s):  
Francesco Balduzzi ◽  
Giovanni Ferrara ◽  
Alberto Babbini ◽  
Guido Pratelli
Keyword(s):  
Cfd Simulation ◽  
Flow Behavior ◽  
Mesh Size ◽  
Critical Issue ◽  
Computational Effort ◽  
Flow Coefficient ◽  
Reciprocating Compressor ◽  
General Applicability ◽  
Suction System ◽  
Pressure Losses

Pressure losses in the suction and discharge components of a reciprocating compressor are the main irreversibilities that affect the global system efficiency; their prediction is a critical issue for the evaluation of the absorbed power. Flow coefficients for automatic valves are often derived from experimental data obtained on a dedicated test bench. Conversely, there is a lack of information concerning the flow behavior in the other components along the gas path and their losses are often taken into account by correcting the valve’s flow coefficient by means of an empirical correlation. CFD simulation of the entirety of the suction and discharge systems is a viable alternative for the prediction of the global pressure losses, although these simulations are very demanding in terms of computational resources. This paper presents an approach to reducing the computational effort required to perform the CFD analysis of a reciprocating compressor. A set of CFD simulations with different suction system geometry configurations has been performed in order to evaluate the dependence of a component pressure loss on the losses of the upstream components. The losses along the suction system can then be evaluated separately from the valve loss by neglecting the presence of the valve itself. The valve can be replaced by an equivalent porous region that straightens the outgoing flow. This approach leads to a decrease in both the mesh size and complexity, and an increase in general applicability.

scholarly journals THERMAL AND COMPUTATIONAL FLUID DYNAMICS ANALYSIS OF AN OIL FIRED CRUCIBLE FURNACE DURING SECONDARY ALUMINUM SMELTING

2020 ◽  
Vol 23 (2) ◽  
pp. 21-27
Author(s):  
Oluwasegun Biodun Owolabi ◽  
◽  
Lawrence Opeyemi Osoba ◽  
Samson Oluropo Adeosun ◽  
◽  
...  
Keyword(s):  
Fluid Dynamics ◽  
Heat Flux ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Theoretical Calculations ◽  
Secondary Aluminum ◽  
Maximum Heat ◽  
Computational Fluid Dynamics Analysis ◽  
Crucible Furnace ◽  
Solid Works

Thermal and computational fluid dynamics (CFD) analysis were explore with knowledge based software such as Solid Works and ANSYS workbench 14.0 for modeling and simulation of an Oil fired crucible furnace used for aluminum secondary smelting. Thermal analysis gives the maximum heat flux and directional heat flux as 8.7596W/mm2 and 8.0349 W/mm2 respectively. CFD simulation shows that the effect of the process parameter on the furnace components is as a result of furnace factors. In brevity theoretical calculations of thermal stress up in the furnace and heat transfer to crucible conform to the modelled results.

scholarly journals A simple method for high-precision evaluation of valve flow coefficient by computational fluid dynamics simulation

2017 ◽  
Vol 9 (7) ◽  
pp. 168781401771370 ◽  
Author(s):  
Xiao-Ming Zhou ◽  
Zhi-Kun Wang ◽  
Yi-Fang Zhang
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Pressure Drop ◽  
Adaptation Strategy ◽  
Flow Coefficient ◽  
Dynamics Simulation ◽  
Accurate Estimation ◽  
Simple Method ◽  
Pressure Losses ◽  
The Difference

Flow coefficient is an important performance index associated with the energy efficiency of a valve, and an effective method to evaluate valve flow coefficient is necessary for valve industry. However, theoretical estimation often results in poor accuracy, while experimental measurements involve significant costs in time and equipment. In this article, a computational fluid dynamics method is proposed to achieve simple and accurate evaluation of valve flow coefficient. For each valve, a computational fluid dynamics model is established containing a valve section, an upstream section, and a downstream section. A grid-adaptation strategy is then applied to improve the accuracy of simulation. To calculate flow coefficient, the most important issue is to determine the net pressure loss induced by valve (Δ Pv). Herein, the overall pressure drop (Δ Po) is obtained first, and the pipe-induced pressure drop (Δ Pp) is estimated by linear fitting. Then, Δ Pv is calculated as the difference between Δ Po and Δ Pp. To ensure accurate estimation of the pressure losses, a length of 26 times of pipe diameter is preferred for the upstream section. The experiments demonstrated that the presented method can accurately predict flow coefficient for various types of valves and thus has great potential to be widely used in the valve industry.

scholarly journals Application of Computational Fluid Dynamics Analysis after Bimaxillary Orthognathic Surgery

2020 ◽  
Vol 10 (5) ◽  
pp. 1676
Author(s):  
Jae Min Song ◽  
Heerim Seo ◽  
Na-Rae Choi ◽  
Eunseop Yeom ◽  
Yong-Deok Kim
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Orthognathic Surgery ◽  
Soft Tissues ◽  
Cfd Simulation ◽  
Computational Fluid Dynamics Analysis ◽  
Bimaxillary Orthognathic Surgery ◽  
Wall Shear

Bimaxillary orthognathic surgery is widely used to treat skeletal class III malocclusion. Changes in jaw position affect the shape of surrounding soft tissues. We used computational fluid dynamics (CFD) simulation to observe changes in airways observed in a patient who underwent bimaxillary orthognathic surgery. For CFD simulation, we performed cone beam computed tomography (CBCT) preoperatively (T0), 3 days postoperatively (T1), and 7 months postoperatively (T2). The values of velocity, pressure drop (ΔP), and wall shear stress all increased 7 months after surgery (Vmax 7.038 m/s to 12.054 m/s, ΔP −7.723 Pa to −53.739 Pa, WSSmax 4.214 Pa to 14.323 Pa). Locations where the velocity and pressure gradients are large included the velopharynx, oropharynx, and epiglottis, with narrow cross-sectional areas. Wall shear stress was also observed at these locations. The velopharynx, oropharynx, and epiglottis are structures most vulnerable to morphological changes, that is, they can easily become obstructed.

scholarly journals 3-D CFD analysis on effect of hub-to-tip ratio on performance of impulse turbine for wave energy conversion

2007 ◽  
Vol 11 (4) ◽  
pp. 157-170 ◽  
Author(s):  
Ajit Thakker ◽  
Mohammed Elhemry
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Energy Conversion ◽  
Wave Energy ◽  
Flow Coefficient ◽  
Dynamics Analysis ◽  
Wave Energy Conversion ◽  
Impulse Turbine ◽  
Guide Vanes ◽  
Computational Fluid Dynamics Analysis

This paper deals with the computational fluid dynamics analysis on effect of hub-to-tip ratio on performance of 0.6 m impulse turbine for wave energy conversion. Experiments have been conducted on the 0.6 m impulse turbine with 0.6 hub-to-tip ratio to validate the present computational fluid dynamics method and to analyze the aerodynamics in rotor and guide vanes, which demonstrates the necessity to improve the blade and guide vanes shape. Computational fluid dynamics analysis has been made on impulse turbine with different hub-to-tip ratio for various flow coefficients. The present computational fluid dynamics model can predict the experimental values with reasonable degree of accuracy. It also showed that the downstream guide vanes make considerable total pressure drop thus reducing the performance of the turbine. The computational fluid dynamics results showed that at the designed flow coefficient of 1.0 the turbine with 0.5 hub-to-tip ratio has better performance compared to 0.55 and 0.6 hub-to-tip ratio turbine.

Computational Fluid Dynamics Analysis of Gas and Particle Flow in Flame Spraying

2000 ◽  
Author(s):  
P.E. Nylén ◽  
R. Bandyopadhyay
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Complex Geometry ◽  
Critical Role ◽  
Reaction Rates ◽  
Flame Spraying ◽  
Powder Size ◽  
Actual Process ◽  
Computational Fluid Dynamics Analysis

Abstract The industrial flame spraying process has been analyzed by three-dimensional Computational Fluid Dynamics (CFD) simulation. The actual process is employed at the Volvo Aero Corporation for coating of fan and compressor housings. It involves the Metco 6P gun where the fuel, a mixture of acetylene and oxygen, flows through a ring of 16 orifices, while the coating material, a powder of nickel-covered bentonite, is sprayed through the flame with a stream of argon as a carrier gas by a central orifice. The gas flow was simulated as a multi-component chemically reacting incompressible flow. The standard, two equations, k-e turbulence model was employed for the turbulent flow field. The reaction rates appeared as source terms in the species transport equations. They were computed from the contributions of the Arrhenius rate expressions and the Magnussen and Hjertager eddy dissipation model. The particles were modeled using a Lagrangian particle spray model. In spite of the complexity of the system, the complex geometry and the numerous chemical reactions, the simulations produced fairly good agreement with experimental measurements. The powder size distribution was found to play a critical role in the amount of unmelted fraction of particles. The modeling approach seems to give a realistic description of the physical phenomena involved in flame spraying, albeit some model refinement is needed.

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