Experimental tests and CFD simulations of a horizontal wave flow turbine under the joint waves and currents

2021 ◽  
Vol 237 ◽  
pp. 109480
Author(s):  
Yu Cao ◽  
Andong Liu ◽  
Xiaochuan Yu ◽  
Ziyan Liu ◽  
Xiaobo Tang ◽  
...  
Keyword(s):  
Experimental Tests ◽  
Wave Flow ◽  
Cfd Simulations ◽  
Horizontal Wave ◽  
Waves And Currents

scholarly journals Investigation of the Performances of a Diesel Engine Operating on Blended and Emulsified Biofuels from Rapeseed Oil

Energies ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 6661
Author(s):  
Vladimir Anatolyevich Markov ◽  
Bowen Sa ◽  
Sergey Nikolaevich Devyanin ◽  
Anatoly Anatolyevich Zherdev ◽  
Pablo Ramon Vallejo Maldonado ◽  
...  
Keyword(s):  
Diesel Engine ◽  
Rapeseed Oil ◽  
Characteristic Curve ◽  
Motor Fuel ◽  
Experimental Tests ◽  
Operating Conditions ◽  
Test Results ◽  
Cfd Simulations ◽  
Brake Thermal Efficiency ◽  
Flow Simulations

The article discusses the possibility of using blended biofuels from rapeseed oil (RO) as fuel for a diesel engine. RO blended diesel fuel (DF) and emulsified multicomponent biofuels have been investigated. Fuel physicochemical properties have been analyzed. Experimental tests of a diesel engine D-245 in the operating conditions of the external characteristic curve and the 13-mode test cycle have been conducted to investigate the effect of these fuels on engine performances. CFD simulations of the nozzle inner flow were performed for DF and ethanol-emulsified RO. The possibility of a significant improvement in brake thermal efficiency of the engine has been noted. The efficiency of using blended biofuels from RO as a motor fuel for diesel engines has been evaluated based on the experimental test results. It was shown that in comparison with the presence of RO in emulsified multicomponent biofuel, the presence of water has a more significant effect on NOx emission reduction. The content of RO and the content of water in the investigated emulsified fuels have a comparable influence on exhaust smoke reduction. Nozzle inner flow simulations show that the emulsification of RO changes its flow behaviors and cavitation regime.

scholarly journals Numerical and experimental analyses for the improvement of surface instant decontamination technology through biocidal agent dispersion: Potential of application during pandemic

PLoS ONE ◽  
2021 ◽  
Vol 16 (5) ◽  
pp. e0251817
Author(s):  
Paulo Roberto Freitas Neves ◽  
Turan Dias Oliveira ◽  
Tarcísio Faustino Magalhães ◽  
Paulo Roberto Santana dos Reis ◽  
Luzia Aparecida Tofaneli ◽  
...  
Keyword(s):  
Experimental Tests ◽  
Cfd Simulations ◽  
New Device ◽  
Qualitative And Quantitative ◽  
Droplet Concentration ◽  
Computational Fluid Dynamics Cfd ◽  
Suspended Droplet ◽  
The Impact ◽  
Disinfection Chamber ◽  
Important Form

The transmission of SARS-CoV-2 through contact with contaminated surfaces or objects is an important form of transmissibility. Thus, in this study, we evaluated the performance of a disinfection chamber designed for instantaneous dispersion of the biocidal agent solution, in order to characterize a new device that can be used to protect individuals by reducing the transmissibility of the disease through contaminated surfaces. We proposed the necessary adjustments in the configuration to improve the dispersion on surfaces and the effectiveness of the developed equipment. Computational Fluid Dynamics (CFD) simulations of the present technology with a chamber having six nebulizer nozzles were performed and validated through qualitative and quantitative comparisons, and experimental tests were conducted using the method Water-Sensitive Paper (WSP), with an exposure to the biocidal agent for 10 and 30 s. After evaluation, a new passage procedure for the chamber with six nozzles and a new configuration of the disinfection chamber were proposed. In the chamber with six nozzles, a deficiency was identified in its central region, where the suspended droplet concentration was close to zero. However, with the new passage procedure, there was a significant increase in wettability of the surface. With the proposition of the chamber with 12 nozzles, the suspended droplet concentration in different regions increased, with an average increase of 266%. The experimental results of the new configuration proved that there was an increase in wettability at all times of exposure, and it was more significant for an exposure of 30 s. Additionally, even in different passage procedures, there were no significant differences in the results for an exposure of 10 s, thereby showing the effectiveness of the new configuration or improved spraying and wettability by the biocidal agent, as well as in minimizing the impact caused by human factor in the performance of the disinfection technology.

scholarly journals Digital Twinning Process for Stirred Tank Reactors/Separation Unit Operations through Tandem Experimental/Computational Fluid Dynamics (CFD) Simulations

Processes ◽  
2020 ◽  
Vol 8 (11) ◽  
pp. 1511
Author(s):  
Blaž Oblak ◽  
Simon Babnik ◽  
Vivian Erklavec-Zajec ◽  
Blaž Likozar ◽  
Andrej Pohar
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Mixing Time ◽  
Tracer Tests ◽  
Flow Distribution ◽  
Experimental Tests ◽  
Cfd Simulations ◽  
Experimental Conditions ◽  
Separation Unit ◽  
Time Required

Computational fluid dynamics simulations (CFD) were used to evaluate mixing in baffled and unbaffled vessels. The Reynolds-averaged Navier−Stokes k–ε model was implemented in OpenFOAM for obtaining the fluid flow field. The 95% homogenization times were determined by tracer tests. Experimental tests were conducted by injecting sodium chloride into the vessel and measuring the conductivity with two conductivity probes, while the simulations replicated the experimental conditions with the calculation of the transport of species. It was found that the geometry of the system had a great effect on the mixing time, since the irregular flow distribution, which can be obtained with baffles, can lead to local stagnation zones, which will increase the time needed to achieve the homogenization of the solute. It was also found that measuring local, pointwise concentrations can lead to a high underestimation of the global mixing time required for the homogenization of the entire vessel. Dissolution of sucrose was also studied experimentally and by mathematical modeling. The dissolution of sucrose was found to be kinetically limited and a very good agreement was found between the experiments and the modeling approach. The extent of the applicability of CFD simulations was evaluated for enabling rapid process design via simulations.

Prediction of Wave-in-Deck Forces on Fixed Jacket-Type Structures Based on CFD Calculations

2008 ◽  
Author(s):  
Benedicte Brodtkorb
Keyword(s):  
Initial Phase ◽  
Central Element ◽  
Load Level ◽  
Impact Loads ◽  
Extreme Waves ◽  
Original Design ◽  
Wave Impact ◽  
Cfd Simulations ◽  
Simplified Method ◽  
Horizontal Wave

The original design requirement for positive air gap is no longer fulfilled for a number of jacket-type structures still in production. When extreme waves impact the deck, the total loads on the structure are increased significantly, so accurate prediction of wave-in-deck forces is a central element in structural reassessment. Simplified methods for evaluating maximum horizontal and vertical loads are useful in an initial phase. In this study, we compare numerical prediction using CFD with the simplified API method for horizontal wave-in-deck load. The global wave impact loads for 0° head-on and 45° oblique waves are calculated for various deck configurations, all heavily equipped (solid). The effect of current is also addressed. In the case of no current, we found that the CFD simulations generally display a reasonable load level compared with the API load method. However, the CFD calculations indicate that the simplified method should be used with care for situations with large upwelling of water and decks with multiple deck girders. A simplified method for predicting vertical wave-in-deck loads on solid decks is developed. The method, first published in DNV-RP-C205, aims to be useful in an initial phase of reassessment.

Flow mixing inside a control-rod guide tube – Experimental tests and CFD simulations

2011 ◽  
Vol 241 (12) ◽  
pp. 4803-4812 ◽  
Author(s):  
Kristian Angele ◽  
Ylva Odemark ◽  
Mathias Cehlin ◽  
Bengt Hemström ◽  
Carl-Maikel Högström ◽  
...  
Keyword(s):  
Experimental Tests ◽  
Guide Tube ◽  
Cfd Simulations ◽  
Control Rod ◽  
Flow Mixing

A Tank Experimental Research on a Horizontal Wave Flow Turbine Generating Device

2014 ◽  
Vol 953-954 ◽  
pp. 1429-1434
Author(s):  
Ka Tian ◽  
Shi Ming Wang ◽  
Chao Lv
Keyword(s):  
Simple Structure ◽  
Reference Method ◽  
Wave Flow ◽  
Ocean Energy ◽  
Steering Mechanism ◽  
Engineering Problems ◽  
Tank Experiment ◽  
Horizontal Wave ◽  
New Type ◽  
Rotational Direction

Used a new type horizontal wave flow turbine ocean energy device as a prototype for the tank experiment, theoretically analyzed the fluid dynamics and energy capacitation of its key component turbine. Through analyzing the data of the tank experimental of the key component turbine, we found the feasibility of this kind of power device. Besides, the experiment proved a particular characteristics of the turbine of maintaining the same rotational direction whatever the directions of the incoming flow of this kind of turbine. The feature of the turbine can eliminate the complicated steering mechanism, which helped the whole device with the advantage of simple structure. The tank experiment not only provided a practical foundation for optimizing the generating device, but also gave a reference method to solve the similar engineering problems.

CFD and Experimental Analysis of Centrifugal Fans With Forward Curved Blades Used in Electric Motors

2019 ◽  
Author(s):  
S. S. Borges
Keyword(s):  
Cfd Simulation ◽  
Experimental Tests ◽  
Performance Comparison ◽  
Centrifugal Fan ◽  
Electric Motors ◽  
Cfd Simulations ◽  
Interface Models ◽  
Ansys Cfx ◽  
Centrifugal Fans ◽  
Computational Fluid Dynamics Cfd

Abstract This work presents an analysis of the aerodynamic performance of a centrifugal fan with forward curved blades (Sirocco) applied to electric motors. In this analysis were carried out computational fluid dynamics (CFD) simulations and experimental tests for comparison of results. The focus of this analysis is the performance comparison among three different models of general connection interface that are required for the connection between the grids of the rotating and stationary domains of CFD simulation, considering the method adopted by the Ansys CFX, software used as computational tool. Thereby, Frozen Rotor, Stage, and Transient Rotor-Stator were the interface models evaluated. For comparison reference, the experimental data were used to evaluate the performance of each interface models for overall operating range of the fan.

CFD Modelling of a Choke Valve Under Critical Working Conditions

2014 ◽  
Author(s):  
Stefano Malavasi ◽  
Gianandrea Vittorio Messa
Keyword(s):  
Experimental Tests ◽  
Flow Coefficient ◽  
Unexpected Result ◽  
Cfd Model ◽  
Cfd Modelling ◽  
Cfd Simulations ◽  
Gas Industry ◽  
Valve Opening ◽  
Coefficient Versus ◽  
Convective Fluxes

Choke valves are widely used in the oil&gas industry to control the fluid flowing in the system. Some of these valves rely on a “cage and sleeve” functioning, in which an outer, sliding sleeve controls the flow rate by overlapping the holes of an inner, fixed cage. The regulation characteristic of choke valves is typically quantified by the opening curve, which is the plot of the flow coefficient versus the valve opening. Experimental tests performed on a “cage and sleeve” choke valve revealed that the orientation of the holes of the cage affects significantly the flow coefficient. This work focuses on the worst situation encountered, in which an anomalous decreasing trend in the opening curve for large valve openings is accompanied by strong vibrations of the device. CFD simulations were run to provide a physical interpretation of this unexpected result. Due to the complexity of the flow field structure at the origin of this behavior particular attention was paid in properly defining the CFD model; the turbulence model and the differencing scheme for the convective fluxes were found to be the most significant parameters. The CFD runs allowed attributing the anomalous trend of the opening curve to the peculiar interactions of the jets within the cage. At last, a modification of the trim design is suggested for avoiding the malfunctioning of the valve and the abnormal vibrations.

Uncertainty Analysis of Numerical Wave Modelling With Relevance to the Dynamics of Oil Booms

2015 ◽  
Author(s):  
Monica C. Silva ◽  
Marcelo de A. Vitola ◽  
Paulo de Tarso T. Esperança ◽  
Sergio H. Sphaier
Keyword(s):  
Wave Propagation ◽  
Wave Structure ◽  
Navier Stokes ◽  
Stokes Wave ◽  
Wave Flow ◽  
Computational Domain ◽  
Navier Stokes Equation ◽  
Oil Boom ◽  
Waves And Currents ◽  
The Mean

This paper presents the first attempt to estimate the numerical uncertainty in wave propagation studies. This work was motivated by a current project at LabOceano (COPPE/UFRJ) related to studying the dynamic behaviour of oil containment booms on waves and currents. To study the dynamics of an oil boom, the influence of the viscous effect needs to be taken into consideration due to the geometry of the boom. Numerically, this can be achieved using software that solves the Navier-Stokes equation. However, prior to evaluating the wave-structure interaction using a viscous model, it is important to evaluate how the numerical model represents the wave flow only, which is the focus of the present paper. Thus, a model based on the continuity and momentum equations available in the software package StarCCM+ is used to simulate the wave propagation. The computational domain is discretized using a trimmer mesh. The results obtained for a regular wave with a wave steepness (H/L) equal to 0.025 are presented. The numerical uncertainties in the mean wave height and in the mean wave period are estimated along the domain using the methodology proposed by [8]. The wave elevation is also compared with the second-order Stokes wave solution.

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