Influence of Local Vegetation on Fire Spread Mechanisms in Surface Fires
(2024) VBRM05 20241Division of Fire Safety Engineering
- Abstract
- The climate change in northern Europe is not only leading to more extreme weather events but also causing long dry summers. This affects the moisture content of the ground and the vegetation. Causing an increased number of wildfires within Germany posing a risk to the environment, society, and firefighters. Surface fire spread in wildfires can be influenced by several environmental conditions and parameters. As the extensive knowledge gained for the US, Australia, Canada, and southern Europe might be not fully applicable to northern Europe a parametric study is carried out based on a field experiment in Saxony-Anhalt Germany. The present work utilizes the particle model of the wildland-urban interface part implemented in the Fire Dynamics... (More)
- The climate change in northern Europe is not only leading to more extreme weather events but also causing long dry summers. This affects the moisture content of the ground and the vegetation. Causing an increased number of wildfires within Germany posing a risk to the environment, society, and firefighters. Surface fire spread in wildfires can be influenced by several environmental conditions and parameters. As the extensive knowledge gained for the US, Australia, Canada, and southern Europe might be not fully applicable to northern Europe a parametric study is carried out based on a field experiment in Saxony-Anhalt Germany. The present work utilizes the particle model of the wildland-urban interface part implemented in the Fire Dynamics Simulator to analyse numerically the influence of the local vegetation on the surface fire spread. Therefore, a 9 m2 area of grassland is modelled and the influence of parameters such as packing ratio, moisture fraction, gras height, ambient temperature, and others are analysed. The vegetation is represented using particles. The combustion is based on a three-step pyrolysis model. The results show the importance of the energy released in ratio to the energy required for pyrolysis. This is observed in models with lower grass blades, a low packing ratio or high moisture contents as these are not leading to a sustained spread. Furthermore, vegetation-specific pyrolysis kinetic parameters are used. However, the significance of these cannot be identified for the chosen case. The chosen parameters in this work are only based on single measurements or assumptions. Therefore, future research should improve the parameters by analysing a larger number of samples. In addition, it should be investigated for other case studies whether individual pyrolysis kinetic parameters are required or if the default ones are sufficient as the deviations are neglectable compared to the uncertainty of the model. (Less)
- Popular Abstract
- Wildfires are posing an increased risk to communities, environment, and firefighters. Due to recent climate change this has become an emerging problem also in northern Europe. Within this work the influence of local vegetation on wildfire spread is analysed.
Understanding the wildfire behaviour and the influences of different parameters on the fire spread allows to predict the expected fire behaviour during incidents and inform the public in a timely manner.
As an increase in wildfires was identified in northern Europe in the past years it is important to analyse whether findings from other geographic regions are applicable or not. Thus, fire simulations based on a field experiment in Saxony-Anhalt, Germany, are utilized to analyse the... (More) - Wildfires are posing an increased risk to communities, environment, and firefighters. Due to recent climate change this has become an emerging problem also in northern Europe. Within this work the influence of local vegetation on wildfire spread is analysed.
Understanding the wildfire behaviour and the influences of different parameters on the fire spread allows to predict the expected fire behaviour during incidents and inform the public in a timely manner.
As an increase in wildfires was identified in northern Europe in the past years it is important to analyse whether findings from other geographic regions are applicable or not. Thus, fire simulations based on a field experiment in Saxony-Anhalt, Germany, are utilized to analyse the importance of different parameters.
The vegetation in the simulation models is described by grassland in a pine forest. To not only account for the grass blades itself but also for the organic materials underneath the grass blades the combustible materials are modelled in different layers. The difference between the two layers is mainly the bulk density (i.e. ratio between fuel and air) as well as the moisture content.
The wildfires modelled within this work are surface fires. Thus, no tree crowns are involved in the fire. The main spread is caused by the grass blades. Furthermore, some burning after the main flame front passed is identified in the layer underneath the grass blades.
It was found that the amount of combustible material available and its moisture content are crucial for the rate at which wildfires are spreading.
These parameters are dependent on the local vegetation species as well as the typical climate. Thus, the simplified models from other regions might not be fully applicable to predict the spread rate of wildfires within this region. Further work in this field is needed, to be prepared for the coming years. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9157555
- author
- Buhk, Frederik LU
- supervisor
- organization
- course
- VBRM05 20241
- year
- 2024
- type
- H2 - Master's Degree (Two Years)
- subject
- keywords
- Surface fire spread, wildfires, particle model
- report number
- 5721
- other publication id
- LUTVDG/TVBB—5721--SE
- language
- English
- id
- 9157555
- date added to LUP
- 2024-06-05 15:48:00
- date last changed
- 2024-06-05 15:48:00
@misc{9157555,
abstract = {{The climate change in northern Europe is not only leading to more extreme weather events but also causing long dry summers. This affects the moisture content of the ground and the vegetation. Causing an increased number of wildfires within Germany posing a risk to the environment, society, and firefighters. Surface fire spread in wildfires can be influenced by several environmental conditions and parameters. As the extensive knowledge gained for the US, Australia, Canada, and southern Europe might be not fully applicable to northern Europe a parametric study is carried out based on a field experiment in Saxony-Anhalt Germany. The present work utilizes the particle model of the wildland-urban interface part implemented in the Fire Dynamics Simulator to analyse numerically the influence of the local vegetation on the surface fire spread. Therefore, a 9 m2 area of grassland is modelled and the influence of parameters such as packing ratio, moisture fraction, gras height, ambient temperature, and others are analysed. The vegetation is represented using particles. The combustion is based on a three-step pyrolysis model. The results show the importance of the energy released in ratio to the energy required for pyrolysis. This is observed in models with lower grass blades, a low packing ratio or high moisture contents as these are not leading to a sustained spread. Furthermore, vegetation-specific pyrolysis kinetic parameters are used. However, the significance of these cannot be identified for the chosen case. The chosen parameters in this work are only based on single measurements or assumptions. Therefore, future research should improve the parameters by analysing a larger number of samples. In addition, it should be investigated for other case studies whether individual pyrolysis kinetic parameters are required or if the default ones are sufficient as the deviations are neglectable compared to the uncertainty of the model.}},
author = {{Buhk, Frederik}},
language = {{eng}},
note = {{Student Paper}},
title = {{Influence of Local Vegetation on Fire Spread Mechanisms in Surface Fires}},
year = {{2024}},
}