作者要感谢本杰明 Sommerkorn, 加布里埃尔杜邦, 杰克 Eggan 和 Chirawat Sanpakit 谁协助在这里提出的实验。珍妮特 Cobian Iñiguez 承认支持由美国宇航局 MUREP 机构研究机会 (米洛) 授予号码 NNX15AP99A。这项工作也由美国农业部/USDI 国家防火计划通过美国农业部森林服务, PSW 研究站和加州大学河滨分校的协议资助。

警告: 由于以下协议中的几个步骤涉及有可能导致损伤的活动, 因此应确保按照已建立的安全协议 (包括防火) 使用适当的个人防护设备 (PPE)耐磨的衣服和防护眼镜. 
 1. 皇冠燃油床负载电池检测安装程序 <ol> <li> 通过将双弹簧门扣 (参见 材料表 ) 通过钳位和 #39 的销孔来修改 4 C 钳 (参见 图 2 )。使用扣来悬挂皇冠燃料床. </li>
	<li> 使用一组不同的 C 形夹具, 将每个负载应变计单元粘贴到风洞框架的顶部 (请参见 图 2 ). </li>
	<li> 将修改后的 C 形夹具附加到应变计单元的自由端, 扣挂起。将链条连接到皇冠燃料床的平台上. </li>
	<li> 将皇冠燃料床平台从风洞框架中挂起, 将每个皇冠燃料床链连接到登山. </li>
	<li> 一旦四负载单元中的每一个都完全安装并连接到燃料床上, 将它们的导线连接到将用于数据采集的惠斯桥上。用防火绝缘材料盖住负载电池, 如用于防火避难所的那种. </li>
</ol> <img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/56591/56591fig2.jpg"/> 图 2: 风洞顶部燃料床负载电池检测. ( a ) 风洞前视图 ( b ) 修改了登山和皇冠燃料床链的 C 形钳, 它支持皇冠燃料床。( c ) 使用 c 形夹具连接到风洞框架的负载单元。<a href="//ecsource.jove.com/files/ftp_upload/56591/56591fig2large.jpg" target="_blank"> 请单击此处查看此图的较大版本. </a> 
 2. 负载单元校准 注意: 由负载单元产生的信号通过: <img alt="Equation 2" src="/files/ftp_upload/56591/56591eq2.jpg"/> 转换为等效质量
其中, V 是信号, 通常是在毫伏中, A 和 B 是通过校准确定的常量, m 表示质量为克。方程 (2) 的所有参数都是通过为该协议中的皇冠质量仪器开发的自定义仪器控制接口获得的。当第一次使用该系统时, 使用精确的权重来校准负载单元信号。校准常数 A 和 B 将根据测量这些精度权重的负载时产生的信号获得。常量 A 是从以下位置计算的: <img alt="Equation 3" src="/files/ftp_upload/56591/56591eq3.jpg"/> 其中 m t 是试验精度重量的质量, w 是生成的信号。加载到负载单元格上的权重, 而 w, o 对应于在负载单元格上不应用权重时产生的信号. 
<ol> <li> 若要获取校准常量 a , 则挂钩精度权重 (一个好的范围将是 200-500 g) 到第一个加载单元。将精度权重的质量用作公式 (3) 中的参数 m t . </li>
	<li> 使用输入 # 字段将负载单元格增益设置为 128, 如下所示 图 3b , i. 1。这对应于设备允许的最大值. </li>
	<li> 从仪表接口读取输出0的信号输出 (请参见 图 3b , i2)。这是等式 (3) 中 a w 的参数. </li>
	<li> 松开重量并读取显示在仪器界面中的新值 ( 图 3b , i2)。这是参数 a w, o . </li>
	<li> 计算 根据步骤2.1 到2.4 中获得的参数 ( m t 、 a w 、 w、o ) , 并提供了公式. </li>
	<li> 在控制器接口中, 使用上一步中获得的 值 填充每个传感器的 Ch 0-m 值. </li>
	<li> 若要查找偏移值, B , 请删除所有权重, 读取和 #39 中的值; 输出已校准 (g) 和 #39; 框 (参见 图 3c , i2 ), 将此值乘以-1。生成的数字是常量 B, 请在和 #34 中键入此数字; 加法和 #34; Ch 0-一个框 (参见 图 3c , i. 3). </li>
	<li> 对每个负载单元 (0、1、2、3) 重复步骤 2.3-2.8, 系统现在已完全校准; 继续用燃料装载燃料床. </li>
</ol> <img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/56591/56591fig3.jpg"/> 图 3: 加载单元的仪表控制接口数据输入步骤校准. ( a ) 桥接初始设置窗口, 并在第一阶段加载单元校准 ( c ) 窗口中为第二阶段的负载单元校验 ( d ) 窗口进行最后一次加载单元校准阶段, 文件保存在这里, 并开始数据记录。<a href="//ecsource.jove.com/files/ftp_upload/56591/56591fig3large.jpg" target="_blank"> 请单击此处查看此图的较大版本. </a> 
 3. 查帕拉尔和精益燃料床的制备 注意: 每个实验使用2公斤的活 chamise 和0.5 公斤的精益 (白杨丝碎). 
<ol> <li> 从为燃烧收集的燃料堆中收集几瓶1品脱的燃料 (3-4 瓶)。
	<ol> <li> 按照同胞和院长对烘乾样品和获得燃料水分含量 30 所划定的程序进行操作。
	</ol> </li> <li> 从最近收获的 chamise 的捆绑中修剪单个分支, 以删除大于和 #188 的死材和分支材料; 英寸直径。将剩余的带电燃料材料放入容器中进行称量. </li>
	<li> 选择2公斤的修剪 chamise 和0.5 公斤的精益求精使用电子秤。将0.5 公斤的精益放在风洞地板上的地面燃料床平台上, 确保体积密度尽可能均匀。通过在已知区域深度上放置已知的精益量来执行此项设置. </li>
	<li> 拉紧 (绒毛) 压实的精益, 以减少其体积密度, 使其容易燃烧. #160; 加载2公斤的修剪 chamise 到平台上悬挂从负载电池创建高架燃料床。均匀地分散在整个平台上的 chamise 分支, 以产生一个统一的燃料床. </li>
</ol> 4。热电偶排列 注意: K 型热电偶用于测量两个燃料层的温度。数据是通过一个由自定义图形用户界面控制的数据采集系统收集的 (见控制器设计软件的材料表)。热电偶推荐为使用是 24 AWG 热电偶与响应时间 0.9 s. 
<ol> <li> 将十六 24 AWG 热电偶 (导体直径: 0.51054 mm) 的数组连接到数据记录器 (响应时间: 0.9 秒). </li>
	<li> 将6热电偶插入顶部燃料层。把这些热电偶 20 cm 分开并且避免热电偶的联络与分支。将10热电偶插入表面燃料层。把这些表面燃料热电偶 10 cm 分开并且避免热电偶的联络与分支 (参见 图 4 ). </li>
	<li> 通过单击 "#34"、"启动/#34"、"热电偶控制软件" 界面中的按钮来激活数据记录. </li>
</ol> <img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/56591/56591fig4.jpg"/> 图 4: 热电偶阵列表面和顶部燃料层示意图位置. 这里 6 个热电偶入了入冠燃料层数 20 cm 除彼此之外。10 热电偶入了入表面燃料层数 10 cm 分开。<a href="//ecsource.jove.com/files/ftp_upload/56591/56591fig4large.jpg" target="_blank"> 请单击此处查看此图的较大版本. </a> 
 5. 图像获取设置 <ol> <li> 将具有红色标记的可视化引用目标挂载在风洞窗口上方10厘米的间隔处。使用此目标作为参考, 以确定从实验视频的火焰高度. 
	注意: 示例火焰高度显示在 图 5 中. </li>
	<li> 设置照片数据收集。集中在风洞试验区, 调整摄像机焦距, 以捕获整个垂直参考目标以及燃料床区域. </li>
	<li> 设置摄像机数据收集。安装在墙上的万能相机壁挂摄像头, 提供了风洞测试部分的全景. </li>
</ol> <img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/56591/56591fig5.jpg"/> 图 5: 从一个典型的实验中取样火焰高度的照片。用红色标记的蓝色视觉目标作为从实验视频中确定火焰高度的参考。<a href="//ecsource.jove.com/files/ftp_upload/56591/56591fig5large.jpg" target="_blank"> 请单击此处查看此图的较大版本. </a> 
 6. 流设置 注意: 风洞中装有变速风扇。风洞中的气流被预先校准到风扇速度。为了达到预期的风速, 选择了风扇转速 (赫兹)。在目前的试验中, 没有风和1米/秒的风流的情况下进行了研究. 
<ol> <li> 将风扇速度设置为速度控制器上的1米/秒。打开风扇以确保它正常工作. </li>
	<li> 关闭风扇。它现在可以使用了. 
	注: 燃烧建筑物设计用于安全地进行防火实验, 同时从工作空间中疏散烟雾。通知当地消防部门, 正在进行试验以消除假警报的发生. </li>
	<li> 关闭大楼所有的门, 以确保屋顶通风口是唯一可能的烟雾疏散出口. </li>
	<li> 打开空气供应风扇, 从楼面外的建筑物中引入新鲜空气。打开排气扇, 通过屋顶通风口排出烟雾. 
	注: 这将建立一个低速度, 高容积的空气流量从建筑物外垂直上升, 由于轻微的压力差和屋顶开口. </li>
	<li> 在每次试验之前, 使用湿球湿度计测量环境空气的相对湿度和温度. </li>
</ol> 7。点火 (与步骤8同时实施) 注意: 点火过程应由点火机组成员按如下方式进行。为了提高安全性, 建议在点火过程中在试验区附近留有第二名船员. 
<ol> <li> 指示 #39; 点燃和 #39; 用变性乙醇浸泡在怡东表面燃料床的前缘。将酒精瓶放在远离点火区的地方, 使用丁烷炬, 将表面燃料床的一端点燃, 与燃料床的前缘平行。小心, 因为酒精浸泡燃料将容易点燃. </li>
	<li> 一旦燃料床被点燃, 踏出测试区并关闭隧道门。如果试验需要风, 打开风洞风扇. </li>
</ol> 8。启动实验运行 注意: 验证实验是否正确设置后, 应启动摄像机. 
<ol> <li> 打开要录制的摄像机. </li>
	<li> 大声朗读实验编号/代码、日期和实验配置, 以便摄像机上的麦克风记录此信息. </li>
	<li> 指示计算机组通过滴答和 #34 开始数据记录; 启用数据记录和 #34; 在仪表控制界面中选择 (请参见 图 3d , i. 1)。指示点火人点燃燃料。一旦点火机组成员退出风洞, 指示风机组成员启动风洞风扇。这将是实验的开始时间为零 (t = 0). </li>
</ol>

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H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fire+spread+in+chaparral+-+A+comparison+of+laboratory+data+and+model+predictions+in+burning+live+fuels.">Fire spread in chaparral - A comparison of laboratory data and model predictions in burning live fuels.</a> Int. J. Wildl. Fire. 25 (9), 980-994 (2016).</li><li>Omodan, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Fire Behavior Modeling - Experiment on Surface Fire Transition to the Elevated Live Fuel A. , (2015).</li><li>Mulvaney, J. J., Sullivan, A. L., Cary, G. J., Bishop, G. 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作者没有什么可透露的。

在整个实验中, 测量高燃料质量的能力是这项技术的主要优点之一。以前的研究查帕拉尔火灾的重点是只在树冠火启动或只在表面传播, 但不是两者兼而有之。这些研究已经量化了在树冠层点火的可能性, 并离开了对未来工作的研究23。我们的方法允许测量的质量损失, 温度分布和火焰几何的两个层涉及灌木树冠火点火和蔓延。它提供了一种从质量损失率间接推断能量通量的方法。...

在 2016年, 加利福尼亚州总共经历了6986场荒地大火, 消耗了564835英亩的1, 造成数百万美元的损失, 并冒着数百人的健康风险。由于区域地中海气候, 主要燃料来源为这些火是查帕拉尔植被社区2。火灾蔓延在查帕拉尔可以被认为是一个皇冠火, 因为主要的燃料, 烧伤是提升3。共同存在与主要地居住的冠层数, 是死的表面燃料层数, 包括铸造的叶子、分支和草本植物生长在和在各自的灌木之间。火将更容易启动在死表面燃料层。一旦表面火点燃, 火可能转移到冠层, 在火释放的能量急剧增加。虽然查帕拉尔火灾通常被模拟为火灾蔓延在深表面燃料4, 有有限的研究查帕拉尔火灾的树冠火灾。

查帕拉尔的树冠特征, 包括叶片颗粒形状, 与北方针叶林不同, 其中大部分研究都是在那里发生的。众多的实验室和野外规模研究已经调查了野火动力学的各个方面6,5,7,3,8,9,10 ,11,12。在实验室实验领域, 有几项研究分析了风和燃料性质等参数对查帕拉尔冠火行为的影响。Lozano7检测了在两个独立的树冠燃料层存在下的顶火起爆特性。在 Tachajapong et al.3, 在风洞内燃烧了离散表面和树冠层, 并进行了表面火灾的表征。只有冠火起爆被充分描述留下充分的分析传播为未来工作。Li et al.11报告了火焰的传播, 虽然单查帕拉尔灌木。在相关工作中, 克鲁兹et al.10,9开发了一个模型来预测在展开的表面火之上的针叶树叶的点火。对查帕拉尔燃料的燃烧特性进行了研究, 并对散装燃料和个体叶片的试验进行了探讨13,14,15,16。Dupuy et al.13通过在圆柱筐中燃烧燃料, 研究了松松树针和精益的燃烧特性。他们观察到, 在这些燃料中, 火焰高度通过2/5 幂定律与热释放率有关, 正如先前在文献1718中所报告的那样。Sun et al.14在类似的圆柱筐中燃烧查帕拉尔燃料, 以分析三查帕拉尔燃料的燃烧特性: chamise (Adenostoma 三)、ceanothus (ceanothus crassifolius) 和 manzanita (Arctostaphylos glandulosa)。
在上述实验室研究的结果的激励下, 我们的目的是提出一种方法来描述在表面和灌木树冠层的传播。此外, 我们的目的是澄清一些关键的特征, 决定了表面-冠层相互作用的程度。为此, 我们开发了实验实验室方法, 研究在荒地表面燃料燃烧的垂直转变为在高架灌木燃料中蔓延的火灾。在这些类型的火灾中, 将火翻译成树冠, 被称为加冠, 在适当的条件下可持续传播。一般而言, 查帕拉尔的火灾行为是由地形、天气和燃料19决定的。结果表明, 风影响能量释放率在燃料5,3,8,20。
多孔燃料中的火蔓延可以看作是一系列的过渡或阈值, 必须跨越才能成功21。精力充沛地, 燃料微粒点燃, 如果它接受的热量的数量结果在气体的混合物成功地反应与氧气。当燃烧粒子的热量点燃相邻的燃料粒子时, 产生的火焰就会扩散。如果火势能够跨越可燃燃料元件之间的空隙, 就会蔓延到地面。如果火焰的表面火能够垂直传播到树冠的灌木和树木, 火灾行为的重大变化, 包括增加的热释放率, 往往被观察到, 由于更大的可用性燃料。荒地火灾中的热能动力学包括几个尺度, 从非常大的规模, 如在大型火灾, 往往需要气候建模, 小规模需要化学尺度动力学建模。在这里, 我们处理实验风洞尺度行为建模;对于化学尺度的纤维素燃烧研究, 读者被称为工作, 如沙利文et al.22
自2001年以来, 我们进行了各种实验, 检查了一些实验室规模的能量阈值23,8,24,25,26, 27, 重点是与查帕拉尔相关的带电燃料。虽然室外测量的火可以提供更逼真的结果, 受控环境的风洞允许划定各种参数的影响。例如, 控制风对于查帕拉尔的树冠火灾尤其重要, 例如在南加州, foehn 类型的风, 称为圣安娜风, 是典型的火灾事件的驱动因素。由于本文所述方法的主要动力是研究风和其他受控参数对查帕拉尔火灾蔓延的影响, 本研究在实验室规模风洞中进行。读取器由 Silvani et al.定向到工作28用于现场测量查帕拉尔火灾中的温度, 类似于此处所示。有关风对火势蔓延影响的实地测量, 请参阅莫兰迪et al.29
通过量化概率, 对影响查帕拉尔燃料扩散的几个参数进行了实验分析火传播成功在高架燃料床8。目前的实验研究涉及的方法是开发的研究查帕拉尔树冠火灾蔓延的模拟表面燃料和皇冠燃料在测试段的低速风洞。表面燃料是建模与精益求精 (干碎木材)。表面燃料床被安置在风洞的地面水平在标准尺度 (参见图 1)。代表顶部燃料床, 一个燃料床与 chamise 被放置在表面燃料床通过悬挂燃料从一个平台上安装在风洞框架 (见图 1)。两个燃料床都被检测温度和质量损失测量;火焰几何学是从实验录像中获得的。测量的参数包括质量损失率、燃料含水量和空气相对湿度。控制的参数是风存在, 表面燃料床和树冠燃料床之间的距离, 以及表面燃料的存在。测量的质量损失率可以用来计算热释放率, 这是定义为: 
<img alt="Equation 1" src="/files/ftp_upload/56591/56591eq1.jpg"> 其中h是燃料燃烧的热量, m是燃料质量, t是时间。
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/56591/56591fig1.jpg"> 
图 1: 风洞实验装置.皇冠燃料床的位置, 地面燃料床, 和隧道风扇已被标记为方便。地面燃料床被安置在风洞的地面水平在标准标度。代表顶部燃料床, chamise 的燃料床被放置在地面燃料床上, 悬挂燃料从一个平台上安装在风洞框架。<a href="//ecsource.jove.com/files/ftp_upload/56591/56591fig1large.jpg" target="_blank">请单击此处查看此图的较大版本.</a>
实验的重点是了解查帕拉尔冠火的行为, 特别是点火, 火焰传播和传播的机制, 火焰锋速度, 和燃料消耗率。为了研究表面火和冠火之间的相互作用, 六配置的表面和顶部燃料床与没有应用风流, 已被烧毁的风洞: 冠燃料只有和没有风 (2), 树冠和表面燃料床分离两个距离与和没有风 (4)。表 1总结了6实验类的实验配置。在表中, 表面燃料层参数表示在试验过程中是否存在表面燃料, 风参数指的是风的存在, 树冠的高度是指顶部燃料床底部与表面底部之间的距离燃料床每项试验都测量了燃料湿度, 但不受控制, 平均燃料含水量为 48%, 而最小和最大值分别为18% 至68%。
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>类</td>
			<td>表面燃料床</td>
			<td>风</td>
			<td>皇冠高度</td>
		</tr>
		<tr>
			<td>一个</td>
			<td>缺席</td>
			<td>无风</td>
			<td>60或70厘米</td>
		</tr>
		<tr>
			<td>b</td>
			<td>缺席</td>
			<td>1毫秒-1</td>
			<td>60或70厘米</td>
		</tr>
		<tr>
			<td>c</td>
			<td>目前</td>
			<td>无风</td>
			<td>60厘米</td>
		</tr>
		<tr>
			<td>d</td>
			<td>目前</td>
			<td>无风</td>
			<td>70厘米</td>
		</tr>
		<tr>
			<td>e</td>
			<td>目前</td>
			<td>1毫秒-1</td>
			<td>60厘米</td>
		</tr>
		<tr>
			<td>f</td>
			<td>目前</td>
			<td>1毫秒-1</td>
			<td>70厘米</td>
		</tr>
	</tbody>
</table>
表 1: 实验配置在这里, 表面燃料床参数表示在试验过程中是否存在表面燃料, 风参数指的是风的存在, 树冠的高度是指顶部燃料床底部与表层燃料床底部之间的距离。
电子秤测量表面燃料质量, 我们开发了一个自定义质量损失系统的冠层。该系统由单独的负载单元连接到悬挂的燃料床的每个角落。消费级摄像机记录了视觉火焰;图像处理的视觉数据使用自定义脚本生成的火焰特性, 包括高度和角度。开发了一个程序, 将视频帧从 RGB (红/绿/蓝) 编码转换为黑白, 通过一个光强阈值的过程。火焰的边缘是从黑白视频帧中获得的。最大火焰高度被定义为火焰边缘的最高点, 同时也获得了火焰的瞬时高度。在图像中, 火焰的高度是从燃料床的底部测量到火焰的最大垂直点。所有的处理代码以及为该协议设计的仪表控制接口都是作者通过他们的软件访问站点提供的。在当地收割现场燃料, 并在24小时内进行实验性烧伤, 减少水分流失。热电偶阵列记录了在风流向方向的燃料床温度, 从而能够计算传播速率。图 1显示了燃料床设置的示意图以及热电偶的布置。实验协议的细节如下。

<table><tbody><tr><td>&lt;strong&gt;Wind Tunnel Instrumentation&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>cDAQ-9178 CompactDAQ Chassis</td><td>National Instruments</td><td>781156-01</td><td></td></tr><tr><td>NI-9213 C Series Temperature Input Module</td><td>National Instruments</td><td>785185-01</td><td></td></tr><tr><td>NI SignalExpress for Windows</td><td>National Instruments</td><td>779037-35&amp;nbsp;</td><td>Newest version, older version used for experiment</td></tr><tr><td>High Temperature Nextel Insulated Thermocouple Elements</td><td>Omega</td><td>XC-24-K-18</td><td></td></tr><tr><td>Thermocouple Extension Wire with Polyvinyl Coated Wire and Tinned Copper Overbraid</td><td>Omega</td><td>EXPP-K-24S-TCB-P</td><td></td></tr><tr><td>Ultra High Temperature Miniature Connectors</td><td>Omega</td><td>SHX-K-M</td><td></td></tr><tr><td>CompuTrac MAX 2000XL&amp;nbsp;</td><td>Arizona Instruments</td><td>MAX-2000XL</td><td>Discontinued, Newer Model Out</td></tr><tr><td>Kestrel 3000 Pocket Weather Meter</td><td>Nielsen-Kellerman</td><td>0830</td><td></td></tr><tr><td>Satorius CPA 34001S&amp;nbsp;</td><td>Sartorius</td><td>25850314</td><td>Discontinued Model</td></tr><tr><td>5 Kg Micro Load Cell (X4)</td><td>Robotshop.com</td><td>RB-Phi-118</td><td>Strain Gauge Load Cell</td></tr><tr><td>Phidget PhidgetBridge Wheatstone Bridge Sensor Interface</td><td>Robotshop.com</td><td>RB-Phi-107</td><td>Interfaces with 4 load cells, performs signal amplification</td></tr><tr><td>#2 Stainless S-Biner (X4)</td><td>Home Depot</td><td>SB2-03-11</td><td>Dual spring gate carabiners used to mount load cells</td></tr><tr><td>2 in. Malleable Iron C-Clamp</td><td>Home Depot</td><td># 4011</td><td>Used to mount load cells</td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;Personal Protective Equipment&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Wildland Firefighter Nomex Shirt</td><td>GSA Advantage</td><td>SH35-5648</td><td></td></tr><tr><td>Fireline 6 oz Wildland Fire Pants</td><td>GSA Advantage</td><td>139702MR SEV16</td><td></td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;Fuels&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Chamise</td><td>Collected in situ</td><td>N/A</td><td></td></tr><tr><td>Natural Shredded Wood Excelsior &amp;ndash; Natural Coarse 50 lbs bail</td><td>Paper Mart</td><td>21-711-88</td><td></td></tr><tr><td>Bernzomatic UL100 Basic Propane Torch Kit</td><td>Home Depot</td><td>UL100KC</td><td></td></tr><tr><td>Isopropyl alcohol</td><td>Convenience store</td><td>N/A</td><td></td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;Video and Photography&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>Nikon D3000 10.2-MP DSLR camera with DX-format sensor and 3x 18x55mm Zoon-NIKKOR VR Image Stabilization Lens</td><td></td><td></td><td></td></tr><tr><td>Sony Handycam Camcorder DCR-SX85</td><td>Amazon.com</td><td>DCR-SX85</td><td></td></tr><tr><td>&lt;strong&gt;Name&lt;/strong&gt;</td><td>&lt;strong&gt;Company&lt;/strong&gt;</td><td>&lt;strong&gt;Catalog Number&lt;/strong&gt;</td><td>&lt;strong&gt;Comments&lt;/strong&gt;</td></tr><tr><td>&lt;strong&gt;Software&lt;/strong&gt;</td><td></td><td></td><td></td></tr><tr><td>NI LabView</td><td>National Instruments</td><td>Student Version</td><td>Used for instrument control and interfacing</td></tr><tr><td>MATLAB Student Version (MATLAB_R2014a)</td><td>Mathworks</td><td>Student Version&amp;nbsp;</td><td>Used for data post-processing including image processing</td></tr></tbody></table>

wind tunnel experiments to study chaparral crown fires

本协议提出了一种实验室技术, 旨在研究查帕拉尔冠火点火和蔓延。在一个低速风洞中进行了实验, 其中两个不同的燃料层被建造来代表查帕拉尔中的表面和树冠燃料。Chamise, 一种常见的查帕拉尔灌木, 包括活冠层。用精益 (碎木) 建造的死燃料表面层。我们开发了一种方法来测量两个燃料层的质量损失、温度和火焰高度。热电偶放置在每层估计温度。摄像机捕捉到了可见的火焰。数字图像后处理产生火焰特性, 包括高度和火焰倾斜。自定义冠质量损失仪器开发了 in-house 测量了冠层质量的演变在烧伤期间。利用技术匹配理论和其他实证研究得出的质量损失和温度趋势。在本研究中, 我们提供了详细的实验程序和有关仪器使用的信息。并对燃料层中燃料质量损失率和温度的代表性结果进行了讨论。

从视频数据中获得了树冠和表面火焰高度数据。实验的典型火焰高度趋势在图 6中介绍。火焰高度行为跟随在太阳中发现et al.14
<img alt="Figure 6" class="xfigimg" src="/files/ftp_upload/56591/56591fig6.jpg"> 
图 6: 估计的顶部火焰高度.这里U = 1 米/秒, 表面-冠分离d = 70 厘...

Watch this Scientific Journal Video about Wind Tunnel Experiments to Study Chaparral Crown Fires at JoVE.com

Wind Tunnel Experiments to Study Chaparral Crown Fires

本议定书描述风洞实验, 旨在研究从地面到查帕拉尔灌木树冠的火灾过渡。

查帕拉尔树冠火灾风洞实验研究

The present protocol presents a laboratory technique designed to study chaparral crown fire ignition and spread. Experiments were conducted in a low ...

wind-tunnel-experiments-to-study-chaparral-crown-fires

Universidad de Cartagena UDEC

Research

JoVE Journal

Engineering

9.6K 次观看.  University of California, Riverside. 本议定书描述风洞实验, 旨在研究从地面到查帕拉尔灌木树冠的火灾过渡。

视频: Wind Tunnel Experiments to Study Chaparral Crown Fires

Exploring the Effects of Atmospheric Forcings on Evaporation: Experimental Integration of the Atmospheric Boundary Layer and Shallow Subsurface

Evaporation is directly influenced by the interactions between the atmosphere, land surface and soil subsurface. This work aims to experimentally study evaporation under various surface boundary conditions to improve our current understanding and characterization of this multiphase phenomenon as well as to validate numerical heat and mass transfer theories that couple Navier-Stokes flow in the atmosphere and Darcian flow in the porous media. Experimental data were collected using a unique soil tank apparatus interfaced with a small climate controlled wind tunnel. The experimental apparatus was instrumented with a suite of state of the art sensor technologies for the continuous and autonomous collection of soil moisture, soil thermal properties, soil and air temperature, relative humidity, and wind speed. This experimental apparatus can be used to generate data under well controlled boundary conditions, allowing for better control and gathering of accurate data at scales of interest not feasible in the field. Induced airflow at several distinct wind speeds over the soil surface resulted in unique behavior of heat and mass transfer during the different evaporative stages.

A protocol for the design and construction of a soil tank interfaced to a small climate controlled wind tunnel to study the effects of atmospheric forcings on evaporation is presented. Both the soil tank and wind tunnel are instrumented with sensor technologies for the continuous in situ measurement of environmental conditions.

在探索大气蒸发强迫的影响:大气边界层和浅地层的实验整合

Evaporation is directly influenced by the interactions between the atmosphere, land surface and soil subsurface. This work aims to experimentally study ...

科研

环境科学

Experimental Methodology for Estimation of Local Heat Fluxes and Burning Rates in Steady Laminar Boundary Layer Diffusion Flames

Modeling the realistic burning behavior of condensed-phase fuels has remained out of reach, in part because of an inability to resolve the complex interactions occurring at the interface between gas-phase flames and condensed-phase fuels. The current research provides a technique to explore the dynamic relationship between a combustible condensed fuel surface and gas-phase flames in laminar boundary layers. Experiments have previously been conducted in both forced and free convective environments over both solid and liquid fuels. A unique methodology, based on the Reynolds Analogy, was used to estimate local mass burning rates and flame heat fluxes for these laminar boundary layer diffusion flames utilizing local temperature gradients at the fuel surface. Local mass burning rates and convective and radiative heat feedback from the flames were measured in both the pyrolysis and plume regions by using temperature gradients mapped near the wall by a two-axis traverse system. These experiments are time-consuming and can be challenging to design as the condensed fuel surface burns steadily for only a limited period of time following ignition. The temperature profiles near the fuel surface need to be mapped during steady burning of a condensed fuel surface at a very high spatial resolution in order to capture reasonable estimates of local temperature gradients. Careful corrections for radiative heat losses from the thermocouples are also essential for accurate measurements. For these reasons, the whole experimental setup needs to be automated with a computer-controlled traverse mechanism, eliminating most errors due to positioning of a micro-thermocouple. An outline of steps to reproducibly capture near-wall temperature gradients and use them to assess local burning rates and heat fluxes is provided.

We describe the use of micro-thermocouples to estimate local temperature gradients in steady laminar boundary layer diffusion flames. By extension of the Reynolds Analogy, local temperature gradients can be further used to estimate the local mass burning rates and heat fluxes in such flames with high accuracy.

在稳定层流边界层扩散火焰本地热通量和燃烧率的估计实验方法

Modeling the realistic burning behavior of condensed-phase fuels has remained out of reach, in part because of an inability to resolve the complex ...

工程学

Combustion Characterization and Model Fuel Development for Micro-tubular Flame-assisted Fuel Cells

Combustion based power generation has been accomplished for many years through a number of heat engine systems. Recently, a move towards small scale power generation and micro combustion as well as development in fuel cell research has created new means of power generation that combine solid oxide fuel cells with open flames and combustion exhaust. Instead of relying upon the heat of combustion, these solid oxide fuel cell systems rely on reforming of the fuel via combustion to generate syngas for electrochemical power generation. Procedures were developed to assess the combustion by-products under a wide range of conditions. While theoretical and computational procedures have been developed for assessing fuel-rich combustion exhaust in these applications, experimental techniques have also emerged. The experimental procedures often rely upon a gas chromatograph or mass spectrometer analysis of the flame and exhaust to assess the combustion process as a fuel reformer and means of heat generation. The experimental techniques developed in these areas have been applied anew for the development of the micro-tubular flame-assisted fuel cell. The protocol discussed in this work builds on past techniques to specify a procedure for characterizing fuel-rich combustion exhaust and developing a model fuel-rich combustion exhaust for use in flame-assisted fuel cell testing. The development of the procedure and its applications and limitations are discussed.

A protocol for creating a model fuel-rich combustion exhaust is developed through combustion characterization and is applied for micro-tubular flame-assisted fuel cell testing and research.

燃烧特性参数和模型燃料开发的微型管状火焰辅助燃料电池

Combustion based power generation has been accomplished for many years through a number of heat engine systems. Recently, a move towards small scale power ...

Using Tree-Rings to Reconstruct Fire History Information from Forested Areas

Annual tree-ring patterns are a source of ecological and environmental information including the history of fires in forested areas. Tree-ring based fire histories include three fundamental phases: field collection, laboratory methods (preparation and dating), and data analysis. Here we provide step-by-step instructions and issues to consider, including the process for selecting the study area, sampling sites, plus how and which fire-scarred trees to sample. In addition, we describe fire-scar sample preparation and dating which are done in the laboratory. Finally, we describe basic analysis and relevant results, including examples from studies that have reconstructed fire history patterns. These studies allow us to understand the historical fire frequency, changes in those frequencies related to anthropogenic factors, and analyzes of how climate influences fire occurrence over time. The description of these methods and techniques should provide a greater understanding of fire history studies that will benefit researchers, educators, technicians, and students interested in this field. These detailed methods will allow new researchers to this field, a resource to start their own work and achieve greater success. This resource will provide a greater integration of tree-ring aspects within other studies and lead to a better understanding of natural processes with forested ecosystems.

This work explains the most appropriate techniques and methods for conducting a fire history study from beginning site selection to final analysis of fire-climate relationship.

Annual tree-ring patterns are a source of ecological and environmental information including the history of fires in forested areas. Tree-ring based fire ...

Experimental Investigation of the Flow Structure over a Delta Wing Via Flow Visualization Methods

It is well known that the flow field over a delta wing is dominated by a pair of counter rotating leading edge vortices (LEV). However, their mechanism is not well understood. The flow visualization technique is a promising non-intrusive method to illustrate the complex flow field spatially and temporally. A basic flow visualization setup consists of a high-powered laser and optic lenses to generate the laser sheet, a camera, a tracer particle generator, and a data processor. The wind tunnel setup, the specifications of devices involved, and the corresponding parameter settings are dependent on the flow features to be obtained.
Normal smoke wire flow visualization uses a smoke wire to demonstrate the flow streaklines. However, the performance of this method is limited by poor spatial resolution when it is conducted in a complex flow field. Therefore, an improved smoke flow visualization technique has been developed. This technique illustrates the large-scale global LEV flow field and the small-scale shear layer flow structure at the same time, providing a valuable reference for later detailed particle image velocimetry (PIV) measurement.
In this paper, the application of the improved smoke flow visualization and PIV measurement to study the unsteady flow phenomena over a delta wing is demonstrated. The procedure and cautions for conducting the experiment are listed, including wind tunnel setup, data acquisition, and data processing. The representative results show that these two flow visualization methods are effective techniques for investigating the three-dimensional flow field qualitatively and quantitatively.

Here, we present a protocol to observe unsteady vortical flows over a delta wing using a modified smoke flow visualization technique and investigate the mechanism responsible for the oscillations of the leading-edge vortex breakdown locations.

基于流动可视化方法的三角洲机翼流动结构实验研究

It is well known that the flow field over a delta wing is dominated by a pair of counter rotating leading edge vortices (LEV). However, their mechanism is ...

气幕燃烧器和生物炭 – 促进森林健康和碳捕获

Continuous In-woods Production of Biochar Using a Trailer-Mounted Air Curtain Burner

Fuel treatments and other forest restoration thinning practices aim to reduce wildfire risk while building forest resilience to drought, insects, and diseases and increasing aboveground carbon (C) sequestration. However, fuel treatments generate large amounts of unmerchantable woody biomass residues that are often burned in open piles, releasing significant quantities of greenhouse gases and particulates, and potentially damaging the soil beneath the pile. Air curtain burners offer a solution to mitigate these issues, helping to reduce smoke and particulates from burning operations, more fully burn biomass residues compared to pile burning, and eliminate the direct and intense fire contact that can harm soil beneath the slash pile. In an air curtain burner, burning takes place in a controlled environment. Smoke is contained and recirculated by the air curtain, and therefore burning can be conducted under a variety of climatic conditions (e.g.,&#160;wind, rain, snow), lengthening the burning season for disposal of slash material. The mobile pyrolysis unit that continuously creates biochar was specifically designed to dispose of residual woody biomass at log landings, green wood at landfills, or salvaged logged materials and create biochar in the process. This high-carbon biochar output can be used to enhance soil resilience by improving its chemical, physical, and biological properties and has potential applications in remediating contaminated soils, including those at abandoned mine sites. Here, we describe the general use of this equipment, appropriate siting, loading methods, quenching requirements, and lessons learned about operating this new technology.

作者聚焦：推进基于地方的生物炭生产，促进生态系统恢复和土壤健康

We describe the use of a place-based mobile pyrolysis unit equipped with an air curtain to continuously create biochar. The technology reduces the need for open slash pile burning, which results in lower emissions and fewer soil impacts. The protocol includes guidelines for site selection, loading, and quenching.

使用拖车式气幕燃烧器连续在林内生产生物炭

Fuel treatments and other forest restoration thinning practices aim to reduce wildfire risk while building forest resilience to drought, insects, and ...

Turbulence Sphere Method: Evaluating Wind Tunnel Flow Quality

Source: Jose Roberto Moreto and Xiaofeng Liu, Department of Aerospace Engineering, San Diego State University, San Diego, CA
Wind tunnel tests are useful in the design of vehicles and structures that are subjected to airflow during their use. Wind tunnel data are generated by applying a controlled air flow to a model of the object being studied. The test model usually has a similar geometry but is a smaller scale compared to the full-sized object. To ensure accurate and useful data is collected during low speed wind tunnel tests, there must be a dynamic similarity of the Reynolds number between the tunnel flow field over the testing model and the actual flow field over the full-sized object.
In this demonstration, wind tunnel flow over a smooth sphere with well-defined flow characteristics will be analyzed. Because the sphere has well-defined flow characteristics, the turbulence factor for the wind tunnel, which correlates the effective Reynolds number to the test Reynolds number, can be determined, as well as the free-stream turbulence intensity of the wind tunnel.

Turbulence Measurements at Varying Air Speeds

湍流球法:评估风洞流量质量

Source: Jose Roberto Moreto and Xiaofeng Liu, Department of Aerospace Engineering, San Diego State University, San Diego, CA
Wind tunnel tests are useful ...

教育

JoVE Science Education

航空工程

Flow Visualization in a Water Tunnel: Observing the Leading-edge Vortex Over a Delta Wing

Source: Jose Roberto Moreto, Gustaaf Jacobs and Xiaofeng Liu, Department of Aerospace Engineering, San Diego State University, San Diego, California
The delta wing, shown in Figure 1D, is a popular design in high-speed airplanes due to its superb performance in transonic and supersonic flight regimes. This type of wing has a small aspect ratio and high sweep angle, which reduces drag at high subsonic, transonic and supersonic flight regimes. The aspect ratio is defined as the wing span divided by the average chord <img align="middle" src="/files/ftp_upload/10459/10459eq1a.jpg" />.
An important advantage of the delta wing is its high stall angle. The stall of a delta wing is delayed compared to the stall of a high aspect ratio wing. This is because the lift of a delta wing is enhanced by the leading-edge vortex over the wing.
An effective way to observe this vortex flow phenomenon and study the vortex breakdown in a delta wing is by visualizing the flow in a water tunnel. By injecting dye in the flow surrounding a model from dye ports on the leading-edge, the vortex development and breakdown can be observed and its position measured. The data can also be used to estimate the stall angle.
<img src="/files/ftp_upload/10459/10459fig1.jpg" />
Figure 1. Typical wing planform shapes: A) Rectangular, with constant chord along span, B) elliptical, C) tapered, with variable chord along the span, and D) delta wing, an aft-swept wing with zero taper ratio.

Flow in a Water Tunnel: Leading-edge Vortex over a Delta Wing

水隧道中的流量可视化:在三角洲翼上观察前沿涡流

Source: Jose Roberto Moreto, Gustaaf Jacobs and Xiaofeng Liu, Department of Aerospace Engineering, San Diego State University, San Diego, California
The ...

查帕拉尔树冠火灾风洞实验研究

摘要

探索更多视频

此视频中的章节

在探索大气蒸发强迫的影响:大气边界层和浅地层的实验整合

在稳定层流边界层扩散火焰本地热通量和燃烧率的估计实验方法

燃烧特性参数和模型燃料开发的微型管状火焰辅助燃料电池

Using Tree-Rings to Reconstruct Fire History Information from Forested Areas

基于流动可视化方法的三角洲机翼流动结构实验研究

使用拖车式气幕燃烧器连续在林内生产生物炭

使用拖车式气幕燃烧器连续在林内生产生物炭

使用拖车式气幕燃烧器连续在林内生产生物炭

湍流球法:评估风洞流量质量

水隧道中的流量可视化:在三角洲翼上观察前沿涡流