Simulation of Airflow in the Burning Cave of an Auxiliary Heating System in a Greenhouse

2018 ◽  
Vol 61 (4) ◽  
pp. 1405-1416
Author(s):  
Zhanyang Xu ◽  
Wenhe Liu ◽  
Tieliang Wang ◽  
Wei Yu ◽  
Yuqing Zhang
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Numerical Simulations ◽  
Heating System ◽  
Experimental Measurements ◽  
Wall Function ◽  
Auxiliary Heating ◽  
Airflow Velocity ◽  
Cave Entrance ◽  
Turbulent Airflow

Abstract. In this study, numerical simulations of airflow were carried out in the burning cave of an auxiliary heating system. Experimental measurements were also conducted to verify the performance of the numerical model, and turbulent airflow in the burning cave was considered. The numerical simulation in the burning cave was performed for three cases:(1) with a baffle at the bottom of the burning cave entrance, (2) without a baffle at the burning cave entrance, and (3) with a baffle at the top of the burning cave entrance. The turbulent airflow was modeled using the realizable k-e turbulence model as well as the non-equilibrium wall function. The airflow velocity was assessed in the burning cave, and some suggestions were given to improve the performance of the burning cave. The results showed that the airflow entering the burning cave differed due to different positions of the baffle. The smoldering combustion was more even and the burning rate could be controlled more easily when the baffle was placed at the top of the burning cave entrance, making the airflow enter the burning cave through the bottom of the baffle. The results also showed that the maximum airflow velocity in the burning cave increased with increased distance between the baffle and the bottom of the burning cave. Keywords: Airflow, Burning cave, Greenhouse, Simulation.

scholarly journals Wind shear over the Nice Côte d'Azur airport: case studies

2013 ◽  
Vol 13 (9) ◽  
pp. 2223-2238 ◽  
Author(s):  
A. Boilley ◽  
J.-F. Mahfouf
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Numerical Simulations ◽  
Wind Shear ◽  
Horizontal Wind ◽  
Wind Profiler ◽  
Measurement Campaign ◽  
Wind Lidar ◽  
Real Time Applications ◽  
Wind Shears

Abstract. The Nice Côte d'Azur international airport is subject to horizontal low-level wind shears. Detecting and predicting these hazards is a major concern for aircraft security. A measurement campaign took place over the Nice airport in 2009 including 4 anemometers, 1 wind lidar and 1 wind profiler. Two wind shear events were observed during this measurement campaign. Numerical simulations were carried out with Meso-NH in a configuration compatible with near-real time applications to determine the ability of the numerical model to predict these events and to study the meteorological situations generating an horizontal wind shear. A comparison between numerical simulation and the observation dataset is conducted in this paper.

scholarly journals Mathematical modeling and numerical simulation of heat dissipation in led bulbs

2020 ◽  
Vol 24 (3 Part A) ◽  
pp. 1877-1884 ◽  
Author(s):  
Diego Alarcón ◽  
Eduardo. Balvís ◽  
Ricardo Bendaña ◽  
Alberto Conejero ◽  
de Fernández ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Numerical Simulation ◽  
Numerical Simulations ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Thermal Contact ◽  
Heat Sinks ◽  
Experimental Measurements ◽  
Heating And Cooling ◽  
The Common

We present a detailed study of heating and cooling processes in LED luminaires with passive heat sinks. Our analysis is supported by numerical simulations as well as experimental measurements, carried on commercial systems used for outdoor lighting. We have focused our analysis on the common case of a single LED source in thermal contact with an aluminum passive heat sink, obtaining an excellent agreement with experimental measurements and the numerical simulations performed. Our results can be easily expanded, without loss of generality, to similar systems.

Multifidelity Recursive Cokriging for Dynamic Systems' Response Modification

2018 ◽  
Vol 141 (1) ◽  
Author(s):  
Luigi Bregant ◽  
Lucia Parussini ◽  
Valentino Pediroda
Keyword(s):  
Numerical Model ◽  
Numerical Simulations ◽  
Dynamic Systems ◽  
System Optimization ◽  
The Other ◽  
Experimental Measurements ◽  
Reciprocal Influence ◽  
Tests And Measurements ◽  
Invaluable Tool ◽  
Mixed Approach

In order to perform the accurate tuning of a machine and improve its performance to the requested tasks, the knowledge of the reciprocal influence among the system's parameters is of paramount importance to achieve the sought result with minimum effort and time. Numerical simulations are an invaluable tool to carry out the system optimization, but modeling limitations restrict the capabilities of this approach. On the other side, real tests and measurements are lengthy, expensive, and not always feasible. This is the reason why a mixed approach is presented in this work. The combination, through recursive cokriging, of low-fidelity, yet extensive, numerical model results, together with a limited number of highly accurate experimental measurements, allows to understand the dynamics of the machine in an extended and accurate way. The results of a controllable experiment are presented and the advantages and drawbacks of the proposed approach are also discussed.

scholarly journals Construction of a numerical model of suspension in a numerical simulation of sedimentation

2018 ◽  
Vol 46 ◽  
pp. 00011
Author(s):  
Krzysztof Kołodziejczyk
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Numerical Simulations ◽  
Particle Composition ◽  
Polydisperse Particle ◽  
Multiphase Systems ◽  
The Moment ◽  
Definition Of ◽  
Selection Of ◽  
The Way

Modeling of multiphase systems, which includes suspensions, is an issue that is continually developed. There are no procedures at the moment that would clearly determine the way in which suspension is defined in numerical simulations. The article presents an analysis of the selection of a numerical model and the definition of the suspension with a polydisperse particle composition.

Determination of Interlaminar Fracture Toughness of CFRP Composite in Mode I Using Numerical Simulation with Cohesive Elements

2020 ◽  
Vol 847 ◽  
pp. 15-21
Author(s):  
Frantisek Sedlacek ◽  
Tomas Kalina ◽  
Karel Raz
Keyword(s):  
Numerical Simulation ◽  
Fracture Toughness ◽  
Numerical Simulations ◽  
Analytical Calculation ◽  
Mode I ◽  
Experimental Measurements ◽  
Cohesive Elements ◽  
Cohesive Failure ◽  
Cfrp Composite

This paper deals with the determination of parameters of the interlaminar failure of the CFRP composite laminate in mode I using numerical simulation with cohesive elements. Knowledge of these parameters is crucial to enable prediction of interlaminar strength of laminates using numerical simulations based on the finite element method with cohesive elements. There are several standardized experimental measurements for determining mode I parameters but not all that are needed for numerical simulations. However, the determination of these parameters and their evolution during cohesive failure is very problematic even if the experimental data is available. This paper deals with the design of a methodology for how to determine these parameters using the fitting process of experimental measurement and numerical simulation. The experimental measurements were done on double cantilever beam specimens according to ASTM standards. The numerical simulations were performed in the Siemens Simcenter software with NX Nastran solver. The numerical model with the obtained parameters shows very good agreement with the experimental measurements. compared to the average experimental values and the analytical calculation, the difference of fracture toughness is up to 1.6 %

A Computational Study of Turbulent Airflow and Tracer Gas Diffusion in a Generic Aircraft Cabin Model

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Khosrow Ebrahimi ◽  
Zhongquan C. Zheng ◽  
Mohammad H. Hosni
Keyword(s):  
Transport Model ◽  
Computational Study ◽  
Flow Behavior ◽  
Gas Diffusion ◽  
Wall Function ◽  
Tracer Gas ◽  
Airflow Velocity ◽  
Aircraft Cabin ◽  
Cfd Models ◽  
Turbulent Airflow

In order to study the capability of computational methods in investigating the mechanisms associated with disease and contaminants transmission in aircraft cabins, the computational fluid dynamics (CFD) models are used for the simulation of turbulent airflow and tracer gas diffusion in a generic aircraft cabin mockup. The CFD models are validated through the comparisons of the CFD predictions with corresponding experimental measurements. It is found that using large eddy simulation (LES) with the Werner-Wengle wall function, one can predict unsteady airflow velocity field with relatively high accuracy. However in the middle region of the cabin mockup, where the recirculation of airflow takes place, the accuracy is not as good as that in other locations. By examining different k-ε models, the current study recommends the use of the RNG k-ε model with the nonequilibrium wall function as an Reynolds averaged Navier-Stokes model for predicting the steady-state airflow velocity. It is also found that changing the nozzle height has a significant effect on the flow behavior in the middle and upper part of the cabin, while the flow pattern in the lower part is not affected as much. Through the use of LES and species transport model in simulating tracer gas diffusion, a very good agreement between predicted and measured tracer gas concentration is achieved for some monitoring locations, but the agreement level is not uniform for all the locations. The reasons for the deviations between prediction and measurement for those locations are discussed.

Numerical Simulation of Vertical Forced Plume in a Crossflow of Stably Stratified Fluid

1995 ◽  
Vol 117 (4) ◽  
pp. 696-705 ◽  
Author(s):  
Robert R. Hwang ◽  
T. P. Chiang
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Cross Section ◽  
Three Dimensional ◽  
Experimental Measurements ◽  
Secondary Vortex ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Vortex Pairs ◽  
Plume Flows

In this study, an investigation using a three-dimensional numerical model, which treats conservation of mass, momentum, and salinity simultaneously, was carried out to study the character of a vertical forced plume in a uniform cross-stream of stably linear stratified environment. A k-ε turbulence model was used to simulate the turbulent phenomena and close the solving problem. The performance of the three-dimensional model is evaluated by comparison of the numerical results with some available experimental measurements. Results indicate that the numerical computation simulates satisfactorily the plume behavior in a stratified crossflow. The secondary vortex pairs in the cross section induced by the primary one change as the plume flows downstream. This denotes the transformation of entrainment mechanism in stratified crossflow.

scholarly journals Wind shear over the Nice Côte d'Azur airport: case studies

2013 ◽  
Vol 1 (2) ◽  
pp. 855-894
Author(s):  
A. Boilley ◽  
J.-F. Mahfouf
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Numerical Simulations ◽  
Wind Shear ◽  
Horizontal Wind ◽  
Wind Profiler ◽  
Measurement Campaign ◽  
Wind Lidar ◽  
Real Time Applications ◽  
Wind Shears

Abstract. The Nice Côte d'Azur international airport is subject to horizontal low-level wind shears. Detecting and predicting these hazards is a major concern for aircraft security. A measurement campaign took place over the Nice airport in 2009 including 4 anemometers, 1 wind lidar and 1 wind profiler. Two wind shear events were observed during this measurement campaign. Numerical simulations were carried out with Meso-NH in a configuration compatible with near-real time applications to determine the ability of the numerical model to predict these events and to study the meteorological situations generating a horizontal wind shear. A comparison between numerical simulation and the observation dataset is conducted in this paper.

scholarly journals THE CALCULATION AND MEASUREMENT OF THE NATURAL FREQUENCIES OF THE BUCKET WHEEL EXCAVATOR SCHRS 1320/4X30

Transport ◽  
2010 ◽  
Vol 25 (3) ◽  
pp. 269-277 ◽  
Author(s):  
Jakub Gottvald
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Dynamic Load ◽  
Natural Frequencies ◽  
Numerical Models ◽  
Dynamic Properties ◽  
Experimental Measurements ◽  
The Real ◽  
Comparison Of Results

Natural frequencies and shapes are the basic dynamic properties of each structure. On the basis of their knowledge, the sensitivity of the structure to a dynamic load could be estimated. While designing, natural frequencies are based on calculations and numerical simulations. However, computational numerical models do not exactly correspond with real structures and there are many details which have to be simplified. It means that the real natural frequencies of structures may differ from the calculated ones. It is advantageous to verify the calculated results by suitable experimental measurements in case of structures where a dynamic load dominates. The paper deals with the experimental measuring of the natural frequencies of the bucket wheel excavator SchRs 1320/4x30 and a comparison of results obtained from experimental measurements and detailed numerical simulation applying ANSYS.

Simulation for Startup Transients in a Natural Circulation Boiling Loop

2008 ◽  
Author(s):  
S. P. Lakshmanan ◽  
P. Pradeep Kumar ◽  
Manmohan Pandey ◽  
Kannan N. Iyer
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Numerical Simulations ◽  
Natural Circulation ◽  
Boiling Water ◽  
Boiling Water Reactors ◽  
Test Facility ◽  
Current Interest ◽  
Water Reactors ◽  
Experimental Findings

Startup of natural circulation boiling water reactors is of current interest due to the transients that occur at low pressure and low power conditions. Numerical simulation can be a useful tool for studying startup transients and for devising appropriate startup procedure. In the present work, a numerical model of an experimental test facility has been developed with RELAP5/MOD3.4. This model has been used to devise a startup procedure, which has been successfully implemented in the test facility. Numerical simulations for the startup transients have been done with the RELAP5 model and results have been compared with experimental findings. The nature of oscillations predicted by numerical simulations is similar to that observed in the experiment. This study demonstrated one possible method for developing startup procedures for natural circulation boiling water reactors.

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