scholarly journals Thermo-Fluid Dynamics Analysis of Fire Smoke Dispersion and Control Strategy in Buildings

Energies ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 6000
Author(s):  
Ricardo S. Gomez ◽  
Túlio R. N. Porto ◽  
Hortência L. F. Magalhães ◽  
Antonio C. Q. Santos ◽  
Victor H. V. Viana ◽  
...  
Keyword(s):  
Fluid Dynamic ◽  
Exhaust System ◽  
Volumetric Flow Rate ◽  
Pollutant Dispersion ◽  
Vertical Displacement ◽  
Fire Dynamics ◽  
Layer Interface ◽  
Smoke Dispersion ◽  
Smoke Layer ◽  
And Control

Smoke is the main threat of death in fires. For this reason, it becomes extremely important to understand the dispersion of this pollutant and to verify the influence of different control systems on its spread through buildings, in order to avoid or minimize its effects on living beings. Thus, this work aims to perform thermo-fluid dynamic study of smoke dispersion in a closed environment. All numerical analysis was performed using the Fire Dynamics Simulator (FDS) software. Different simulations were carried out to evaluate the influence of the exhaust system (natural or mechanical), the heat release rate (HRR), ventilation and the smoke curtain in the pollutant dispersion. Results of the smoke layer interface height, temperature profile, average exhaust volumetric flow rate, pressure and velocity distribution are presented and discussed. The results indicate that an increase in the natural exhaust area increases the smoke layer interface height, only for the well-ventilated compartment (open windows); an increase in the HRR accelerates the downward vertical displacement of the smoke layer and that the 3 m smoke curtain is efficient in exhausting smoke, only in the case of poorly ventilated compartments (i.e., with closed windows).

MEASUREMENT OF SMOKE LAYER INTERFACE HEIGHT FOR HOT SMOKE TESTS IN TUNNELS

Equipment ◽  
2006 ◽  
Author(s):  
L. H. Hu ◽  
W. K. Chow ◽  
Y. Z. Li ◽  
R. Huo
Keyword(s):  
Layer Interface ◽  
Smoke Layer

scholarly journals Numerical Investigations on the Propagation of Fire in a Railway Carriage

Energies ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4999
Author(s):  
Matthew Craig ◽  
Taimoor Asim
Keyword(s):  
Fire Spread ◽  
Ignition Energy ◽  
Fire Dynamics ◽  
Fire Propagation ◽  
Average Temperature ◽  
Smoke Density ◽  
Smoke Layer ◽  
Most Significant Change ◽  
Computational Fluid Dynamics Cfd ◽  
Safety Guidelines

In this study, advanced Computational Fluid Dynamics (CFD)-based numerical simulations have been performed in order to analyse fire propagation in a standard railway compartment. A Fire Dynamics Simulator (FDS) has been employed to mimic real world scenarios associated with fire propagation within railway carriages in order to develop safety guidelines for railway passengers. Comprehensive parametric investigations on the effects of ignition location, intensity and cabin upholstery have been carried out. It has been observed that a fire occurring near the exits of the carriage results in a lower smoke layer height, due to the local carriage geometry, than an identical fire igniting at the center of the carriage. This in turn causes the smoke density along the aisleway to vary by around 30%. Reducing the ignition energy by half has been found to restrict combustion, thus reducing smoke density and carbon exhaust gases, reducing the average temperature from 170 °C to 110 °C. Changing the material lining of the seating has been found to cause the most significant change in output parameters, despite its relative insignificance in bulk mass. A polyester sample produces a peak carbon monoxide concentration of 7500 ppm, which is 27× greater compared with nylon. This difference has been found to be due to the fire spread and propagation between fuels, signifying the polyester’s unsuitability for use in railway carriages.

scholarly journals Micrometeorological Modeling of Radiative and Convective Effects with a Building-Resolving Code

2011 ◽  
Vol 50 (8) ◽  
pp. 1713-1724 ◽  
Author(s):  
Yongfeng Qu ◽  
Maya Milliez ◽  
Luc Musson-Genon ◽  
Bertrand Carissimo
Keyword(s):  
Urban Areas ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Pollutant Dispersion ◽  
Urban Setting ◽  
Dynamical Model ◽  
Neutral Atmosphere ◽  
Atmospheric Flow ◽  
Ongoing Work ◽  
The One

AbstractIn many micrometeorological studies with computational fluid dynamics, building-resolving models usually assume a neutral atmosphere. Nevertheless, urban radiative transfers play an important role because of their influence on the energy budget. To take into account atmospheric radiation and the thermal effects of the buildings in simulations of atmospheric flow and pollutant dispersion in urban areas, a three-dimensional (3D) atmospheric radiative scheme has been developed in the atmospheric module of the Code_Saturne 3D computational fluid dynamic model. On the basis of the discrete ordinate method, the radiative model solves the radiative transfer equation in a semitransparent medium for complex geometries. The spatial mesh discretization is the same as the one used for the dynamics. This paper describes ongoing work with the development of this model. The radiative scheme was previously validated with idealized cases. Here, results of the full coupling of the radiative and thermal schemes with the 3D dynamical model are presented and are compared with measurements from the Mock Urban Setting Test (MUST) and with simpler modeling approaches found in the literature. The model is able to globally reproduce the differences in diurnal evolution of the surface temperatures of the different walls and roof. The inhomogeneous wall temperature is only seen when using the 3D dynamical model for the convective scheme.

scholarly journals A Numerical Analysis of the Fire Characteristics after Sprinkler Activation in the Compartment Fire

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3099 ◽  
Author(s):  
Ho Trong Khoat ◽  
Ji Tea Kim ◽  
Tran Dang Quoc ◽  
Ji Hyun Kwark ◽  
Hong Sun Ryou
Keyword(s):  
Experimental Data ◽  
Numerical Analysis ◽  
Fire Suppression ◽  
Compartment Fire ◽  
Fire Dynamics ◽  
Fire Dynamics Simulator ◽  
Safety Design ◽  
Smoke Layer ◽  
Fire Characteristics ◽  
Sprinkler Spray

Understanding fire characteristics under sprinkler spray is valuable for performance-based safety design. However, fire characteristics during fire suppression by sprinkler spray has seldom been studied in detail. In order to present a fire suppression model by sprinkler spray and determine the fire characteristics after sprinkler activation in a compartment, a numerical analysis was conducted using a fire dynamics simulator (FDS). A simple fire suppression model by sprinkler spray was calibrated by comparing ceiling temperatures from experimental data. An extinguishing coefficient of 3.0 was shown to be suitable for the fire suppression model. The effect of sprinkler spray on the smoke layer during fire suppression was explained, revealing a smoke logging phenomenon. In addition, the smoke, which spread under the influence of the sprinkler spray, was also investigated. The temperature, velocity, and mass flow rate of the smoke layer through the doorway was significantly reduced during fire suppression compared to a free burn case.

The influence of nozzle deflection on fluid dynamic and infrared characteristics of a two-dimensional convergent–divergent vectoring exhaust system

2019 ◽  
Vol 233 (12) ◽  
pp. 4646-4662
Author(s):  
Hao Wang ◽  
Honghu Ji ◽  
Haohao Lu
Keyword(s):  
Mass Flow ◽  
Infrared Radiation ◽  
Deflection Angle ◽  
Thrust Force ◽  
Fluid Dynamic ◽  
Dynamic Performance ◽  
Exhaust System ◽  
Two Dimensional ◽  
Radiation Characteristics ◽  
Significant Information

Superior maneuverability and good infrared stealthy properties are two key points of the future aircraft. A two-dimensional convergent–divergent (2D-CD) vectoring exhaust system can improve the maneuverability of aircrafts and has been widely applied to the latest generation aircrafts. Understanding fluid dynamic and infrared radiation characteristics of the 2D-CD vectoring exhaust systems under different conditions of the nozzle deflection is very crucial, which can provide significant information for the suppression of the infrared radiation property of the 2D-CD vectoring exhaust system. In this paper, by means of computational fluid dynamics, the fluid dynamic and infrared radiation characteristics of the 2D-CD vectoring exhaust system are studied at subsonic cruise status with nozzle deflection angles from 0 to 20°, and the results are compared with those of the baseline axisymmetric exhaust system. The results indicate that the fluid dynamic performance of a properly designed 2D-CD vectoring exhaust system is equivalent to the fluid dynamic performance of the baseline axisymmetric exhaust system. When the nozzle deflection angle is less than 5°, the mass flow and thrust force of the 2D-CD vectoring exhaust system are almost unchanged, and with the increase of the nozzle deflection angles, the mass flow and thrust force decrease rapidly. The thrust force deflection angles lag behind the nozzle deflection angles all the time, and as the nozzle deflection angle increases, the difference between them decreases. The direction of the maximum infrared radiation of the 2D-CD vectoring exhaust system deflects with the deflection of the nozzle, and the mean integrated infrared radiation intensity of the exhaust system decreases with the increase of nozzle deflection angles.

Testing of Throttle Valve Prototype Controlled by Piezoelectric Stack

2011 ◽  
Vol 177 ◽  
pp. 47-64 ◽  
Author(s):  
Janusz Pluta ◽  
Marek Sibielak
Keyword(s):  
Volumetric Flow Rate ◽  
Flow Section ◽  
Test Results ◽  
Labview Software ◽  
Functional Correlation ◽  
Throttle Valve ◽  
Section Area ◽  
Electrically Actuated ◽  
Flow Intensity ◽  
And Control

This paper aims to present the results of the testing a single-stage electrically actuated throttle valve, in which a piezoelectric stack was used for adjustment of the flow section area of the throttle aperture. The valve prototype was built based on a proprietary design, using the components of a standard manufactured overflow valve. The complete valve was designed on the basis of the results of simulation tests performed on a mathematical model. The constitutive equations presented herein, describing all critical phenomena and influences present in the component, were applied for the modelling of the piezoelectric stack. Laboratory tests were carried out to establish the valve’s characteristics, describing its usefulness for control of flow intensity. LabView software was used for measuring the data gathered. The test results, after conversion, were developed using the Matlab/Simuling software package. This paper presents the most notable results of the tests of a normally open valve equipped with a high-voltage piezoelectric stack. Based on the results obtained, the functional correlation between the volumetric flow rate, pressure drop in the throttling aperture and control signal input to the piezoelectric stack were determined. Due to the comprehensive approach involved, the material presented herein may be prove useful to designers of valves and hydraulic units using piezoelectric stacks for controlling their operating units.

Deterministic–stochastic approach to compartment fire modelling

2008 ◽  
Vol 465 (2104) ◽  
pp. 1029-1041 ◽  
Author(s):  
V Bertola ◽  
E Cafaro
Keyword(s):  
Deterministic Model ◽  
Random Noise ◽  
Stochastic Approach ◽  
Fire Dynamics ◽  
Arbitrary Degree ◽  
Compartment Fires ◽  
External Perturbations ◽  
Fire Modelling ◽  
Smoke Layer ◽  
Suitable Potential

A generalized Semenov model is proposed to describe the dynamics of compartment fires. It is shown that the transitions to flashover or to extinction can be described in the context of the catastrophe theory (or the theory of dynamical systems) by introducing a suitable potential function of the smoke layer temperature. The effect on the fire dynamics of random perturbations is then studied by introducing a random noise term accounting for internal and external perturbations with an arbitrary degree of correlation. While purely Gaussian perturbations (white noise) do not change the behaviour of the fire with respect to the deterministic model, perturbations depending on the model variable (‘coloured’ noise) may drive the system to different states. This suggests that the compartment fires can be controlled or driven to extinction by introducing appropriate external perturbations.

An Investigation Into Performance Characteristics of an Axial Flow Fan Using CFD for Electronic Devices

2015 ◽  
Author(s):  
Hafiz M. Hashim ◽  
Baris Dogruoz ◽  
Mehmet Arik ◽  
Murat Parlak
Keyword(s):  
Three Dimensional ◽  
Axial Flow ◽  
Volumetric Flow Rate ◽  
Critical Issue ◽  
Data Sets ◽  
Axial Fan ◽  
Flow Rates ◽  
Cad Models ◽  
And Control ◽  
Control Association

Rotating fans are widely utilized in thermal management applications and their accurate characterization has recently become even a more critical issue for thermofluids engineers. The present study investigates the characterization of an axial fan computationally and experimentally. Using the three-dimensional CAD models of the fan, a series of computational fluid dynamics (CFD) simulations were performed to determine the flow and pressure fields produced by the axial mover over a range of flow rates. In order to validate the computational model findings, experiments were conducted to obtain the pressure drop values at different flow rates in an AMCA (Air Movement and Control Association) standard 210-99, 1999 wind tunnel. These data sets were also compared with the fan vendor’s published testing data. A reasonably good agreement was obtained among the data from these three separate sources. Furthermore, an attempt was made to understand the overall fan efficiency as a function of the volumetric flow rate. It was determined that the maximum overall fan efficiency was less than 27% correlating well with the computational results.

CFD Application for Performance Based Safety Verification of Reinforced Concrete Beam in Computer Simulation Building Fire

2012 ◽  
Vol 601 ◽  
pp. 190-195
Author(s):  
Chia Chun Yu ◽  
Shih Cheng Wang ◽  
Cherng Shing Lin ◽  
Te Chi Chen
Keyword(s):  
Reinforced Concrete ◽  
Fire Protection ◽  
Fluid Dynamic ◽  
Bending Moment ◽  
Fire Intensity ◽  
Fire Damage ◽  
Rc Beams ◽  
Fire Dynamics ◽  
Rc Structures ◽  
Building Fire

More than 90% of the buildings in Taiwan use reinforced concrete (RC) structures. Before or after fire damage, whether the RC structure accord Performance Based Design (PBD) fire code or safe evaluation are important in building fire protection verification. However, obtaining fire thermal parameters detailed quantitative data from building fire tests or actual building fires are difficult. Therefore, computational fluid dynamic (CFD) integration to simulate fire scenarios has been widely utilized in fire protection engineering. This study utilizes Fire Dynamics Simulator (FDS) fire model and PHOENICS field model software to simulate fire development and beams inner temperature variation. The structural strength estimated using beam cross-sections temperature to investigate dynamic ultimate bending moment (Mu) of RC beams. This integration method can investigate the influence of different beam positions, fire intensity, fire duration and fire damage sustained (two or three faces heated) for RC beams fire protection safe verification.

Thermo-Fluid Dynamic of Gaseous Pollutant Dispersion: Fundamentals and Applications in Thermal Power Plants

2018 ◽  
Vol 20 ◽  
pp. 34-54
Author(s):  
A.J. Ferreira Gadelha ◽  
T.R. Nascimento Porto ◽  
T.H. Freire de Andrade ◽  
Severino Rodrigues de Farias Neto ◽  
A.G. Barbosa de Lima
Keyword(s):  
Wind Velocity ◽  
Power Plants ◽  
Fluid Dynamic ◽  
Thermal Power ◽  
Pollutant Dispersion ◽  
Thermal Power Plants ◽  
Cfd Simulations ◽  
Gaseous Pollutant ◽  
Ansys Cfx ◽  
Dispersion Problem

This work focuses on the pollutant dispersion problem with particular reference to thermal power plants. A powerful mathematical modeling to predict gaseous pollutant concentration at atmosphere and different CFD simulations results by Ansys CFX®software are presented. The gaseous pollutant dispersion was evaluated by analyzing of different process parameters as wind velocity, gas emission rate and temperature. The study confirms wind velocity as main variable that strongly affecting dispersion phenomena.

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