Experiments and Numerical Simulations of Flow Patterns of Water Droplets From Fire-Fighting Helicopters

2000 ◽  
Author(s):  
Kohyu Satoh ◽  
Kohei Sagae ◽  
Kunio Kuwahara ◽  
K. T. Yang
Keyword(s):  
Numerical Simulations ◽  
Forest Fires ◽  
Water Drop ◽  
Real Life ◽  
Large Earthquake ◽  
Flow Patterns ◽  
Design Tool ◽  
Fire Fighting ◽  
Water Application ◽  
Water Droplets

Abstract In large forest fires over wide areas, aerial fire fighting with water drop from helicopters has been widely employed in the world. After the large earthquake fires in Japan, possibilities were raised to employ similar fire-fighting technique to city fires. However, forest and city fires were inherently different in nature and require different fire-fighting implementations. Since the city fires are concentrated in extent and isolated, thus requiring more dense water application to extinguish fires. As a result, accurate engineering data on the optimum water application relative to a given fire are critically needed to design fire-fighting strategies. This study describes the experiments carried out in open fields using real-life helicopters, in comparison with the 3-D numerical simulations. Numerical simulations can provide reasonable flow patterns of the water droplets from the helicopters, and can be used as a design tool for implementing the fire-fighting technique for real city fires.

A Numerical Study of Forest Fire Progression and Fire Suppression by Aerial Fire Fighting

2004 ◽  
Author(s):  
Kohyu Satoh ◽  
Kunio Kuwahara ◽  
K. T. Yang
Keyword(s):  
Forest Fire ◽  
Forest Fires ◽  
High Speed ◽  
Laboratory Experiments ◽  
Numerical Study ◽  
Water Drop ◽  
Fire Suppression ◽  
Critical Issue ◽  
Fire Fighting ◽  
Cfd Simulations

Forest fires are of common occurrence all over the world, which cause severe damages to valuable natural resources and human lives. In the recent California Fire, which burned 300,000 hectors of land, the disaster danger could reasonably be predicted, but early control of fires by means of aerial fire fighting might have been failed in that situation. Also in Japan, there are similar problems in the aerial fire fighting. Most forest fires occur in the daytime and the fires are freely in progress without any control during the nighttime. Therefore, it is important to attack the fires when there is daylight. The water dropped by helicopters is not always sufficient to control fires, since the quantity of water that can be carried aloft is a critical issue. Large amount of water can be dropped from aircrafts, but the high-speed flight of aircrafts may be dangerous in the mountain, where tall trees and steel towers with electric wires may exist. Therefore, those aircrafts have to fly at much higher altitudes than helicopters, while the water drop at high altitudes changes water into mist in the air. The objective of this study is to examine the methods to prevent the ignition by firebrands in the downwind area by applying water through the aerial fire fighting. However, tests by real aircrafts to obtain such information would be too costly. Therefore, the patterns of water drop from aircrafts were examined in CFD simulations, together with the investigation of needed water drop rate based on the forest fire statistics, the previous real aircraft tests and laboratory experiments. It has been found in the simulations that the water supply with the water density of 2 L/m2 is effective to control fires and the patterns of dropping water are reasonable.

Soil water repellency persistence after recurrent forest fires on Mount Carmel, Israel

2013 ◽  
Vol 22 (4) ◽  
pp. 515 ◽  
Author(s):  
Naama Tessler ◽  
Lea Wittenberg ◽  
Noam Greenbaum
Keyword(s):  
Organic Matter ◽  
Soil Water ◽  
Forest Fires ◽  
Water Drop ◽  
Chemical Properties ◽  
Water Repellency ◽  
Mediterranean Ecosystem ◽  
Long Term Effects ◽  
Soil Water Repellency ◽  
Chemical Properties Of Soils

Variations in forest fires regime affect: (1) the natural patterns of community structure and vegetation; (2) the physico-chemical properties of soils and consequently (3) runoff, erosion and sediment yield. In recent decades the Mediterranean ecosystem of Mount Carmel, north-western Israel, is subjected to an increasing number of forest fires, thus, the objectives of the study were to evaluate the long-term effects of single and recurrent fires on soil water repellency (WR) and organic matter (OM) content. Water repellency was studied by applying water drop penetration time (WDPT) tests at sites burnt by single-fire, two fires, three fires and unburnt control sites. Water repellency in the burnt sites was significantly lower than in the unburnt control sites, and the soil maintained its wettability for more than 2 decades, whereas after recurrent fires, the rehabilitation was more complicated and protracted. The OM content was significantly lower after recurrent than after a single fire, causing a clear proportional decrease in WR. The rehabilitation of WR to natural values is highly dependent on restoration of organic matter and revegetation. Recurrent fires may cause a delay in recovery and reduced productivity of the soil for a long period.

scholarly journals La gestione degli incendi boschivi in Canton Ticino: tentativo di una sintesi storica | Forest fire management in Canton Ticino: attempting a historical overview

2004 ◽  
Vol 155 (7) ◽  
pp. 263-277 ◽  
Author(s):  
Marco Conedera ◽  
Gabriele Corti ◽  
Paolo Piccini ◽  
Daniele Ryser ◽  
Francesco Guerini ◽  
...  
Keyword(s):  
Forest Fire ◽  
Forest Fires ◽  
Fire Management ◽  
Southern Alps ◽  
Fire Fighting ◽  
Historical Overview ◽  
Forest Fire Management ◽  
Structural Measures ◽  
The Impact ◽  
Legislative Measures

The Southern Alps, in particular the Canton Ticino, is the region of Switzerland that is most affected by the phenomenon of forest fires. Therefore, the cantonal authorities are continually confronted with problems of prevention, fire fighting and mitigation of the effects of forest fires. In this article forest fire management in Canton Ticino is analyzed in historical terms, verifying in particular the impact of the methods used and the improvement of technology addressing the frequency of events and the extent of burned surfaces. In this way it has been possible to show how a few structural measures (better organization of fire fighting crews and equipment, introduction of aerial fire fighting techniques, electrification followed by construction of shelters along railway lines, etc.) have rather reduced the extent of burned surfaces, while legislative measures such as restrictions of open fires help to reduce the number of forest fires.

scholarly journals Observation and analysis of long-periodic modes in a confluence with dominant tributary inflow

2018 ◽  
Vol 40 ◽  
pp. 05043
Author(s):  
Laurent Schindfessel ◽  
Tom De Mulder ◽  
Mia Loccufier
Keyword(s):  
Numerical Simulations ◽  
Secondary Flow ◽  
Significant Influence ◽  
Laboratory Experiments ◽  
Flow Patterns ◽  
Modal Decomposition ◽  
Periodic Oscillations

Confluences with dominant tributary inflow are found to exhibit long-periodic alternations of the flow patterns. They are shown to exist both in laboratory experiments and in numerical simulations. By means of a modal decomposition, insight is given into these long-periodic oscillations. The origin of these oscillations is investigated and their significant influence on the secondary flow patterns in the downstream channel is revealed.

scholarly journals CFD simulation of flow patterns in unbaffled stirred tank with CD-6 impeller

2012 ◽  
Vol 18 (4-1) ◽  
pp. 535-546 ◽  
Author(s):  
Tamphasana Devi ◽  
Bimlesh Kumar
Keyword(s):  
Numerical Simulations ◽  
Cfd Simulation ◽  
Flow Patterns ◽  
Industrial Applications ◽  
Spatial Variations ◽  
Stirred Tank ◽  
Rushton Turbine ◽  
Stirred Vessels

Understanding the flow in stirred vessels can be useful for a wide number of industrial applications. There is a wealth of numerical simulations of stirring vessels with standard impeller such as Rushton turbine and pitch blade turbine. Here, a CFD study has been performed to observe the spatial variations (angular, axial and radial) of hydrodynamics (velocity and turbulence field) in unbaffled stirred tank with Concave-bladed Disc turbine (CD-6) impeller. Three speeds (N=296, 638 & 844.6 rpm) have been considered for this study. The angular variations of hydrodynamics of stirred tank were found very less as compared to axial and radial variations.

Basin Tests and Numerical Simulations of Wake-Induced Oscillations of In-Line Risers in Subcritical/Critical Regime

2018 ◽  
Author(s):  
Vincent Levasseur ◽  
Charles Leca ◽  
Benjamin Rousse ◽  
Francois Pétrié
Keyword(s):  
Numerical Simulations ◽  
Industrial Design ◽  
Design Tool ◽  
Critical Regime ◽  
Incoming Flow ◽  
Numerical Approaches

This paper adresses Wake Induced Oscillations in the transition between subcritical and critical regime. Both experimental and numerical approaches are proposed and compared here to model tandem risers motion. The main purpose is to enlarge our insights of the behavior of different arrangements of risers in this very tricky range of incoming flow (Re ∈ [134,000; 300,000]) and to assess the CFD ability as an industrial design tool.

scholarly journals Soil Functional Responses to Natural Ecosystem Restoration of a Pine Forest Peucedano-Pinetum after a Fire

Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 286 ◽  
Author(s):  
Edyta Hewelke ◽  
Ewa Beata Górska ◽  
Dariusz Gozdowski ◽  
Marian Korc ◽  
Izabella Olejniczak ◽  
...  
Keyword(s):  
Forest Fires ◽  
Soil Depth ◽  
Water Drop ◽  
Soil Microbial Communities ◽  
Internal Transcribed Spacers ◽  
Water Infiltration ◽  
Species Structure ◽  
Natural Ecosystem ◽  
Functional Responses ◽  
Soil System

Progressing climate change increases the frequency of droughts and the risk of the occurrence of forest fires with an increasing range and a dramatic course. The availability of water and its movement within an ecosystem is a fundamental control of biological activity and physical properties, influencing many climatic processes, whereas soil water repellency (SWR) is a key phenomenon affecting water infiltration into the soil system. Focusing on wide-spectrum effects of fire on the soil system, the research was conducted on a pine stand (Peucedano-Pinetum W. Mat. (1962) 1973) in Kampinos National Park located in central Poland, affected by severe and weak fires, as well as control plots. The main aim of the study was to examine the regeneration of the ecosystem 28 months after the occurrence of a fire. The effect of SWR and soil moisture content, total organic carbon, nitrogen and pH, and gain an understanding of the environmental conditions and processes that shaped the evolution of the species structure of soil microorganism communities (fungal vs. bacterial) have been examined. The Water Drop Penetration Time (WDPT) test was used to assess spatial variability of SWR in 28 plots. Soil bacterial and fungal communities were analysed by Illumina’MISeq using 16S rRNA and Internal Transcribed Spacers 1 (ITS1) regions in six selected plots. After a relatively wet summer, elevated hydrophobicity occurred in areas affected by a weak fire as much as 20 cm into the soil depth. The severe fire and subsequent increase in the richness of the succession of non-forest species contributed to the elimination of hydrophobicity. SWR was more closely linked to the structure and diversity of soil microbial communities than soil physicochemical properties that took place in response to the fire. A statistically significant relationship between the relative occurrence of microorganisms (≥ 1.0% in at least one of the samples) and SWR was established for the following fungi and bacteria species: Archaeorhizomyces sp., Leotiomycetes sp., Byssonectria fusispora, Russula vesca, Geminibasidium sp., family Isosphaeraceae and Cyanobacteria (class 4C0d-2, order MLE1-12). Insight into the functional roles of the individual identified microbial taxa that may be responsible for the occurrence of hydrophobicity was also presented.

Study on Countercurrent Flow in a PWR Hot Leg Under Reflux Cooling

2010 ◽  
Author(s):  
Noritoshi Minami ◽  
Michio Murase ◽  
Akio Tomiyama
Keyword(s):  
Numerical Simulations ◽  
Flow Pattern ◽  
Flow Rate ◽  
Current Flow ◽  
Air Flow ◽  
Flow Patterns ◽  
Interfacial Friction ◽  
Air Flow Rate ◽  
Counter Current Flow ◽  
Counter Current

In this paper, results of experiments and numerical simulations for counter-current flow in a pressurized water reactor hot leg under reflux cooling are summarized. In the experiments, we used two types of small scale PWR hot legs. One was a 1/5th scale rectangular duct, and the other was a 1/15th scale circular pipe. Air and water were used for gas and liquid phases. The air flow rate and the supplied water flow rate were varied to observe flow pattern and measure the counter-current flow limitation (CCFL) characteristics. Flow patterns in the elbow and the inclined section were strongly affected by those in the horizontal section. In the 1/15th scale circular pipe experiments, CCFL characteristics obtained by increasing the air flow rate differed from those obtained by decreasing it. CCFL characteristics corresponded to the flow pattern transition. In the numerical simulations, we used a three-dimensional two-fluid model to evaluate the capability of predicting counter-current flow in the hot leg. Good agreements between measured and predicted flow patterns and CCFL characteristics were obtained by using an appropriate set of correlations for interfacial friction coefficient. We also carried out simulations of actual hot leg conditions to examine the effects of fluid properties and size. Predicted flow patterns and CCFL characteristics were close to those of scale model calculations. We concluded the combination of calculation model and interfacial friction coefficients used in this study can predict the counter-current flow in a hot leg.

scholarly journals Fighting forest fires in the Kuibyshev Region in 1931-1940: a little-known aspect of the ecological history of the Middle Volga region

2021 ◽  
Vol 10 (2) ◽  
pp. 184-188
Author(s):  
Evgeny Vladimirovich Voeykov
Keyword(s):  
Forest Fires ◽  
Large Scale ◽  
Fire Fighting ◽  
Volga Region ◽  
Annual Number ◽  
Environmental Damage ◽  
State Archive ◽  
Forest Protection ◽  
Middle Volga Region ◽  
Middle Volga

The paper deals with the spread of forest fires and measures to combat them in the course of implementing the policy of preserving the forests of the Volga region in the years of the pre-war five-year plans. The paper is written mainly on the basis of archival materials of the Russian State Archive of Economics, the Central State Archive of the Samara Region, and the State Archive of the Ulyanovsk Region, which were first introduced into historical circulation. In the 1930s, large-scale logging was carried out in the Kuibyshev Region in violation of the rules of forestry. One of the problems of forest exploitation was the growth of forest fires, which caused significant economic and environmental damage. The forest industry trust Sredles and the Srednevolzhsky Forestry Trust could not significantly change the situation with the fire protection of forests for the better. The most unfavorable years for the forests of the Middle Volga region and the Kuibyshev Region were 1933 and 1938. After the creation of the Srednevolzhsky (Kuibyshev) Forest Protection Department, the effectiveness of fire-fighting measures increased. Fire fighting was carried out by the most modern means at that time. As a result, the annual number of fires decreased. But it was not possible to completely solve the problem of fires in the forests of the Middle Volga during the third five-year plan.

scholarly journals Numerical Analysis of a DMA Epoxy-Carbon Composite Study

2018 ◽  
Vol 9 (4) ◽  
pp. 101-112
Author(s):  
Paweł KOWALECZKO ◽  
Andrzej PANAS ◽  
Mirosław NOWAKOWSKI
Keyword(s):  
Carbon Fibre ◽  
Numerical Simulations ◽  
Composite Structures ◽  
Fibre Composite ◽  
Real Life ◽  
Elastic Response ◽  
Resin Matrix ◽  
Fibre Reinforcement ◽  
Carbon Fibre Composite ◽  
Model Composite

The results of numerical simulations performed for Dynamic Mechanical Analysis (DMA) measurements of thermal and mechanical (or thermomechanical) properties performed on a model composite structure are presented herein. The simulated elastic response of an epoxy-carbon fibre composite specimen was analysed for a case by which the model specimen was subjected to three-point bending with a free support. The epoxy-carbon fibre composite studied as explained herein exhibited extreme differences between the resilient properties of the epoxy resin matrix and the carbon fibre reinforcement. In addition, the carbon fibre reinforcement was both internally and structurally anisotropic. The numerical simulations were performed to demonstrate a qualitative dependence of the DMA measurement results on a certain structure of the investigated specimen and to determine if the DMA results could be qualified as effective or apparent. A macro-mechanical model of the specimen was developed and had the numerical calculations run with COMSOL/M, a FEM modelling software suite. The carbon fibre reinforcement was modelled with an orthotropic structure of laminar or circular inclusions with different characteristic dimensions. Representative material properties were assumed from the results of proprietary experimental investigations and certain reference literature data. The effect of the composite layers’ configuration and their characteristic dimensions on the evaluated model’s elastic modulus value was also studied. The results presented herein suggested a qualitative agreement with the results of the DMA investigations performed on real-life composite structures. They also proved the effectiveness of the developed numerical simulation methodology, shown herein, in the DMA of micro- and macromechanical phenomena

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