Experimental and Numerical Investigation on the Effects of the Seeding Properties on LDA Measurements

2005 ◽  
Vol 127 (3) ◽  
pp. 514-522 ◽  
Author(s):  
Angelo Algieri ◽  
Sergio Bova ◽  
Carmine De Bartolo
Keyword(s):  
Particle Size ◽  
High Performance ◽  
Laser Doppler Anemometry ◽  
Two Phase ◽  
Large Particles ◽  
Computational Fluid Dynamics Simulations ◽  
Influence Measurement ◽  
Dynamics Simulations ◽  
Commercial Device ◽  
Good Agreement

The characteristics of the seeding particles, which are necessary to implement the laser Doppler anemometry (LDA) technique, may significantly influence measurement accuracy. LDA data were taken on a steady-flow rig, at the entrance of the trumpet of the intake system of a high-performance engine head. Five sets of measurements were carried out using different seeding particles: samples of micro-balloons sieved to give three different size ranges (25–63μm,90–200μm, and standard as received from the manufacturer 1–200μm), smoke from a “home-made” sawdust burner (particle size ⩽1μm), and fog from a commercial device (particle size around 1μm). The LDA data were compared with the results of two-phase computational fluid dynamics simulations. The comparison showed a very good agreement between the experimental and numerical results and confirmed that LDA measurements with particle dimensions in the order of 1μm or less represent the actual gas velocity. On the contrary, quite large particles, which are often used because of their cost and cleanliness advantages, introduce non-negligible errors.

scholarly journals Effects of reformed fuel on dual-fuel combustion particulate morphology

2019 ◽  
pp. 146808741987978
Author(s):  
Flavio Dal Forno Chuahy ◽  
Tyler Strickland ◽  
Nicholas Ryan Walker ◽  
Sage L Kokjohn
Keyword(s):  
Particle Size ◽  
Fuel Combustion ◽  
Dual Fuel ◽  
Scanning Mobility Particle Sizer ◽  
Reactivity Controlled Compression Ignition ◽  
Condensation Particle Counter ◽  
Computational Fluid Dynamics Simulations ◽  
Dual Fuel Combustion ◽  
Particle Sizer ◽  
Dynamics Simulations

Advancements in catalytic reforming have demonstrated the ability to generate syngas (a mixture of CO and hydrogen) from a single hydrocarbon stream. This syngas mixture can then be used to replace diesel fuel and enable dual-fuel combustion strategies. The role of port-fuel injected syngas, composed of equal parts hydrogen and carbon monoxide by volume, was investigated experimentally for soot reduction benefits under diesel pilot ignition and reactivity controlled compression ignition strategies. Particle size distribution measurements were made with a scanning mobility particle sizer and condensation particle counter for different levels of syngas substitution. To explain the experimental results, computational fluid dynamics simulations utilizing a detailed stochastic soot model were used to validate and initialize additional simulations that isolate mixing and chemistry effects. Based on these simulations, the influence of adding syngas on soot particle size and quantity is discussed.

Three-Dimensional, Two-Phase Computational Fluid Dynamics Simulations of Alkaline Diaphragm Water Electrolysis Devices

2020 ◽  
Vol MA2020-02 (38) ◽  
pp. 2495-2495
Author(s):  
Joseph Steven Lopata ◽  
Sanggyu Kang ◽  
Hyun-Seok Cho ◽  
Chang Hee Kim ◽  
Sirivatch Shimpalee
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Three Dimensional ◽  
Water Electrolysis ◽  
Two Phase ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

Simulations of an Air-Ventilated Strut Crossing Water Surface at Variable Yaw Angles

2018 ◽  
Author(s):  
Konstantin I. Matveev ◽  
Miles P. Wheeler ◽  
Tao Xing
Keyword(s):  
Water Surface ◽  
Free Water ◽  
Suction Side ◽  
Complex Flow ◽  
Air Ventilation ◽  
History Of ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Lift Control ◽  
Good Agreement

Hydrodynamic devices intended to produce lift, control actions, or propulsion can be prone to air ventilation when operating near the free water surface. The atmospheric air may propagate to the low-pressure zones around these devices located under the nominal water level. This often leads to performance degradation of hydrodynamic systems. Modeling of air-ventilated flows is challenging due to complex flow nature and many factors in play. In this study, the computational fluid dynamics simulations are carried out for a surface-piercing strut at different yaw angles. At small yaw angles, the strut underwater surfaces remain wetted, whereas at large yaw and sufficiently high Froude numbers the suction side becomes air ventilated. At the intermediate yaw angles, both wetted and ventilated flow regimes are possible, and the existence of a specific state depends on the history of the process. The present computational results demonstrate good agreement with available experimental data.

scholarly journals Boxfish swimming paradox resolved: forces by the flow of water around the body promote manoeuvrability

2015 ◽  
Vol 12 (103) ◽  
pp. 20141146 ◽  
Author(s):  
S. Van Wassenbergh ◽  
K. van Manen ◽  
T. A. Marcroft ◽  
M. E. Alfaro ◽  
E. J. Stamhuis
Keyword(s):  
Drag Reduction ◽  
High Performance ◽  
Flow Direction ◽  
Current Theory ◽  
The Body ◽  
Hydrodynamic Drag ◽  
Aerodynamic Design ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

The shape of the carapace protecting the body of boxfishes has been attributed an important hydrodynamic role in drag reduction and in providing automatic, flow-direction realignment and is therefore used in bioinspired design of cars. However, tight swimming-course stabilization is paradoxical given the frequent, high-performance manoeuvring that boxfishes display in their spatially complex, coral reef territories. Here, by performing flow-tank measurements of hydrodynamic drag and yaw moments together with computational fluid dynamics simulations, we reverse several assumptions about the hydrodynamic role of the boxfish carapace. Firstly, despite serving as a model system in aerodynamic design, drag-reduction performance was relatively low compared with more generalized fish morphologies. Secondly, the current theory of course stabilization owing to flow over the boxfish carapace was rejected, as destabilizing moments were found consistently. This solves the boxfish swimming paradox: destabilizing moments enhance manoeuvrability, which is in accordance with the ecological demands for efficient turning and tilting.

scholarly journals Effects of scale and Froude number on the hydraulics of waste stabilization ponds

2017 ◽  
Vol 77 (1) ◽  
pp. 239-247
Author(s):  
Isabela De Luna Vieira ◽  
Jhonatan Barbosa Da Silva ◽  
Carlos Nobuyoshi Ide ◽  
Johannes Gérson Janzen
Keyword(s):  
Froude Number ◽  
Reynolds Numbers ◽  
Transport Processes ◽  
Tracer Transport ◽  
Waste Stabilization Ponds ◽  
Stabilization Ponds ◽  
Waste Stabilization ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations ◽  
Good Agreement

Abstract This paper presents the findings from a series of computational fluid dynamics simulations to estimate the effect of scale and Froude number on hydraulic performance and effluent pollutant fraction of scaled waste stabilization ponds designed using Froude similarity. Prior to its application, the model was verified by comparing the computational and experimental results of a model scaled pond, showing good agreement and confirming that the model accurately reproduces the hydrodynamics and tracer transport processes. Our results showed that the scale and the interaction between scale and Froude number has an effect on the hydraulics of ponds. At 1:5 scale, the increase of scale increased short-circuiting and decreased mixing. Furthermore, at 1:10 scale, the increase of scale decreased the effluent pollutant fraction. Since the Reynolds effect cannot be ignored, a ratio of Reynolds and Froude numbers was suggested to predict the effluent pollutant fraction for flows with different Reynolds numbers.

scholarly journals Considerations for the design of bottom intake systems

2017 ◽  
Vol 20 (1) ◽  
pp. 232-245 ◽  
Author(s):  
José M. Carrillo ◽  
Luis G. Castillo ◽  
Juan T. García ◽  
Álvaro Sordo-Ward
Keyword(s):  
Numerical Models ◽  
Turbulence Models ◽  
Discharge Coefficients ◽  
Ansys Cfx ◽  
Laboratory Results ◽  
Computational Fluid Dynamics Simulations ◽  
The Many ◽  
Dynamics Simulations ◽  
Laboratory Experiences ◽  
Good Agreement

Abstract Knowing the scarcity of water in the southeast of Spain and how the rain occurs, we considered the design of intake systems in ephemeral riverbeds in order to try to capture part of the runoff flow. The intake systems generally consist of a rack located in the bottom of a river channel, so that the water collected passes down the rack and leads to the side channel. This behaviour has been studied in the laboratory by several researchers. However, due to the many effects that occur on the bars, it is not possible to analyse the whole problem of characterization with traditional methodologies. For instance, the wetted rack length necessary to collect a required flow presents important differences depending on what each author has considered relevant. Computational fluid dynamics simulations have been done to improve the knowledge of the hydraulic phenomenon observed in different laboratory experiences, for which we have previously calibrated the numerical models using laboratory results. The ANSYS CFX code was selected. Several two-equation turbulence models have been considered. The results show differences smaller than 1% in the wetted rack length, and discharge coefficients also present good agreement.

Calculation of Melting Curve of Aluminum under Pressure through Molecular Dynamics Simulations

2011 ◽  
Vol 421 ◽  
pp. 151-155
Author(s):  
Jin Xi Li ◽  
Zhi Qiang Han
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Melting Curve ◽  
Melting Process ◽  
Phase Method ◽  
Experiment Data ◽  
Two Phase ◽  
Dynamics Simulations ◽  
Solid Liquid ◽  
Good Agreement

The melting curve is an important thermodynamic property in studies of solid-liquid phase transitions. It can be calculated via molecular dynamics simulations. We simulated the melting process of pure Al with three methods, the heat-until-it-melts (HUM) method, the two-phase method and the hysteresis method. The results calculated via HUM method is approximately 20% higher than experiment data while the results calculated via two-phase method and hysteresis method are in good agreement with experiment data.

scholarly journals Numerical Simulations as Tool to Predict Chemical and Radiological Hazardous Diffusion in Case of Nonconventional Events

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
J.-F. Ciparisse ◽  
A. Malizia ◽  
L. A. Poggi ◽  
O. Cenciarelli ◽  
M. Gelfusa ◽  
...  
Keyword(s):  
Industrial Applications ◽  
Gas Release ◽  
Open Environment ◽  
Nuclear Explosive ◽  
Dust Mobilization ◽  
Computational Fluid Dynamics Simulations ◽  
Dangerous Substances ◽  
Dynamics Simulations ◽  
Pure Research ◽  
Good Agreement

CFD (Computational Fluid Dynamics) simulations are widely used nowadays to predict the behaviour of fluids in pure research and in industrial applications. This approach makes it possible to get quantitatively meaningful results, often in good agreement with the experimental ones. The aim of this paper is to show how CFD calculations can help to understand the time evolution of two possible CBRNe (Chemical-Biological-Radiological-Nuclear-explosive) events: (1) hazardous dust mobilization due to the interaction between a jet of air and a metallic powder in case of a LOVA (Loss Of Vacuum Accidents) that is one of the possible accidents that can occur in experimental nuclear fusion plants; (2) toxic gas release in atmosphere. The scenario analysed in the paper has consequences similar to those expected in case of a release of dangerous substances (chemical or radioactive) in enclosed or open environment during nonconventional events (like accidents or man-made or natural disasters).

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