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Copy file name to clipboardExpand all lines: Manuals/Bibliography/FDS_general.bib
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volume = {41},
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}
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@TECHREPORT{Leventon:NIST_TN_2282,
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author = {I. Leventon and M. Heck and K. McGrattan and M. Bundy and R. Davis},
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title = {{The Impact of Material Composition on Ignitability and Fire Growth. Volume 1: Full-Scale Burning Behavior of Combustible Solids Commonly Found in Nuclear Power Plants}},
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institution = {National Institute of Standards and Technology},
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year = {2024},
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type = {NIST Technical Note},
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number = {6196-1},
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address = {Gaithersburg, Maryland}
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}
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@BOOK{Leveque:1,
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author = {Leveque, R. J.},
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title = {Finite Volume Methods for Hyperbolic Problems},
Copy file name to clipboardExpand all lines: Manuals/FDS_User_Guide/FDS_User_Guide.tex
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In the second approach, one or more ducts have flows that are not specified, in this case FDS must solve for the pressures at either end of the duct to determine the flow through the duct. As one example, if a tee has three ducts and only one of the ducts has a specified flow, then FDS will use the relative pressure drops along the two other ducts to determine the flow. If no \ct{LOSS} inputs are given, then FDS may not correctly solve for the flow. As another example, losses in the HVAC network limit how quickly flow in the ducts can change over time. If there is a single duct connecting two rooms with no \ct{LOSS} inputs given, then small pressure changes can lead to large changes in duct velocity and increase the risk of a numerical instability. If you specify an HVAC network where flow is being solved for by FDS, then you must provided \ct{LOSS} inputs for each possible flow path. FDS will perform a check at startup and return an error message if it finds insufficient losses have been specified; however, this check may not discover all cases.
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\subsection{HVAC and Unstructured Geometry}
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\label{info:hvac_geom}
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Assigning either a normal HVAC node or a localized leakage HVAC to a GEOM is done using \ct{SURF}. Using the simple example from Section~\ref{info:GEOM_Basics}, an HVAC node named \ct{'MY NODE'} is assigned to the first face by defining a \ct{SURF} with \ct{NODE_ID='MY NODE'}. No other boundary conditions should be set on the \ct{SURF} other than a color or texture. On the node \ct{HVAC} input set \ct{GEOM=T} to indicate FDS needs to look for a \ct{GEOM} and not a \ct{VENT} for the node:
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\begin{lstlisting}
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&SURF ID='NODE SURF',NODE_ID='MY NODE'/
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&GEOM ID='My Solid'
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SURF_ID='NODE SURF','INERT'
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VERTS= -1.0, -1.0, 0.0,
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1.0, -1.0, 0.0,
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0.0, 1.0, 0.0,
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0.0, 0.0, 1.0,
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FACES= 1,3,2, 2,
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1,4,3, 1,
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3,4,2, 1,
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2,4,1, 0 /
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&HVAC ID='MY NODE',TYPE_ID='NODE',GEOM=T,..../
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\end{lstlisting}
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The \ct{SURF} input \ct{NODE_ID} can only be applied to complex geometry. It cannot be used for \ct{OBST} or \ct{VENT}. While more than one \ct{GEOM} and more than one face of a \ct{GEOM} can use the same node, the same node cannot be shared by both a \ct{VENT} and a \ct{GEOM}.
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To apply localized leakage to \ct{GEOM}, the process is similar. \ct{NODE_ID} on \ct{SURF} is still used to link faces of \ct{GEOM} to the localized leakage. The input for the localized leakage changes slightly. The inputs \ct{VENT_ID} and \ct{VENT2_ID} use \ct{GEOM} and \ct{GEOM2} to determine if the respective \ct{ID} is attached to a \ct{VENT} or a \ct{GEOM}. For example, to attach the second vent for a localized leakage path:
$M$ is the vegetation {\em moisture content} or {\em moisture fraction} determined on a dry weight basis, specified with \ct{MOISTURE_FRACTION} on the \ct{SURF} line. $\nu_{\rm char}$ is the mass fraction of Dry Vegetation that is converted to char during pyrolysis, specified with the parameter \ct{NU_MATL} on the \ct{MATL} line that describes the Dry Vegetation. The character string \ct{MATL_ID} on the same \ct{MATL} line indicates the name of the char. $\nu_{\rm O_2,char}$ is the mass of oxygen consumed per unit mass of char oxidized. $\nu_{\rm ash}$ is the mass fraction of char that is converted to ash during char oxidation, specified by \ct{NU_MATL} on the \ct{MATL} line describing the char.
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$M$ is the vegetation {\em moisture content} or {\em moisture fraction} determined on a dry weight basis, specified with \ct{MOISTURE_CONTENT} on the \ct{SURF} line. $\nu_{\rm char}$ is the mass fraction of Dry Vegetation that is converted to char during pyrolysis, specified with the parameter \ct{NU_MATL} on the \ct{MATL} line that describes the Dry Vegetation. The character string \ct{MATL_ID} on the same \ct{MATL} line indicates the name of the char. $\nu_{\rm O_2,char}$ is the mass of oxygen consumed per unit mass of char oxidized. $\nu_{\rm ash}$ is the mass fraction of char that is converted to ash during char oxidation, specified by \ct{NU_MATL} on the \ct{MATL} line describing the char.
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It is assumed that the Dry Vegetation in Eq.~(\ref{pyr_reac}) is 47~\% (by mass) carbon~\cite{Ma:BGS2018} with an effective organic component C$_{3.4}$H$_{6.2}$O$_{2.5}$~\cite{Ritchie:1}. In general, it is assumed that char may be comprised of more than pure carbon and is defined as $\mathrm{C_{x'}O_{z'}A}$ in Eq.~\ref{char_chemistry}. In the specific case where char is composed of pure carbon which reacts completely with O$_2$ to form CO$_2$ then $\nu_{\rm O_2,char}=2.67$ and $\nu_{\rm ash}=0$. A full discussion of the composition of the Char and Fuel Gas is given in Sec.~\ref{veg_pyrolysis_gas_phase}.
The needle is composed of two materials---\ct{'dry pine'} and \ct{'MOISTURE'}. Following the convention used in forestry, the moisture content is expressed via the \ct{MOISTURE_FRACTION}, which is the mass of moisture divided by the mass of {\em dry} vegetation. Do not confuse this with the mass fraction of moisture, $Y_{\rm m}$, which is related to the moisture fraction, $M$, via
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The needle is composed of two materials---\ct{'dry pine'} and \ct{'MOISTURE'}. Following the convention used in forestry, the moisture content is expressed via the \ct{MOISTURE_CONTENT}, which is the mass of moisture divided by the mass of {\em dry} vegetation. Do not confuse this with the mass fraction of moisture, $Y_{\rm m}$, which is related to the moisture fraction, $M$, via
Note that if you specify a \ct{MOISTURE_FRACTION} on the \ct{SURF} line, FDS will automatically add a \ct{MATL} line for \ct{'MOISTURE'} as it is written in Fig.~\ref{vege_inputs}. FDS will also alter the \ct{DENSITY} of the dry vegetation, in this case \ct{'dry pine'}, so that the size and wood content of the particle do not change when moisture is added. The modified density of the ``dry'' vegetation, $\tilde{\rho}_{\rm d}$, is given by:
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Note that if you specify a \ct{MOISTURE_CONTENT} on the \ct{SURF} line, FDS will automatically add a \ct{MATL} line for \ct{'MOISTURE'} as it is written in Fig.~\ref{vege_inputs}. FDS will also alter the \ct{DENSITY} of the dry vegetation, in this case \ct{'dry pine'}, so that the size and wood content of the particle do not change when moisture is added. The modified density of the ``dry'' vegetation, $\tilde{\rho}_{\rm d}$, is given by:
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\tilde{\rho}_{\rm d} = \frac{\rho_{\rm d}} {1-\frac{\rho_{\rm d}}{\rho_{\rm m}} M }
This line inserts 1000 Lagrangian particles representing pine needles randomly within a unit cube. The \ct{MASS_PER_VOLUME} is the mass (kg) of solid needles divided by the volume (m$^3$) they occupy, sometimes called the ``bulk density.'' The parameter \ct{DRY=T} means that if you have specified a \ct{MOISTURE_FRACTION} on the \ct{SURF} line that describes the vegetation, then the actual mass per volume of wet vegetation is
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This line inserts 1000 Lagrangian particles representing pine needles randomly within a unit cube. The \ct{MASS_PER_VOLUME} is the mass (kg) of solid needles divided by the volume (m$^3$) they occupy, sometimes called the ``bulk density.'' The parameter \ct{DRY=T} means that if you have specified a \ct{MOISTURE_CONTENT} on the \ct{SURF} line that describes the vegetation, then the actual mass per volume of wet vegetation is
The presence of the parameter \ct{MASS_PER_VOLUME} automatically triggers the Boundary Fuel Model. Note that its argument of 1 refers to the first layer; the second layer being \ct{Soil}. If you specify \ct{MOISTURE_FRACTION}, FDS will automatically add a \ct{MATL} line for \ct{'MOISTURE'}.
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The presence of the parameter \ct{MASS_PER_VOLUME} automatically triggers the Boundary Fuel Model. Note that its argument of 1 refers to the first layer; the second layer being \ct{Soil}. If you specify \ct{MOISTURE_CONTENT}, FDS will automatically add a \ct{MATL} line for \ct{'MOISTURE'}.
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The drag exerted on the wind flowing through the vegetation is imposed as a force term in the gas phase grid cell adjacent to the boundary:
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The figures below contain predictions of the burning rate of various plastics in a parallel panel apparatus described in Sec.~\ref{NIST_NRC_Parallel_Panels_Description}.
As part of a Nuclear Regulatory Commission (NRC) research project to assess fire behavior in electrical enclosures, rate of spread and heat release rate measurements were made on various plastics lining a parallel panel apparatus. The panels were 0.6~m (2~ft) wide, 2.4~m (8~ft) tall, and separated by 0.3~m (1~ft). A 60~kW propane sand burner was positioned at the base of the two panels. Plastics tested to date include PMMA, PVC, and PBT, cut into 6.4~mm (0.25~in) thick panels. A sketch of the apparatus, originally developed by Factory Mutual, is shown in Fig.~\ref{Parallel_Panel_Sketch}.
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As part of a Nuclear Regulatory Commission (NRC) research project to assess fire behavior in electrical enclosures, rate of spread and heat release rate measurements were made on various materials lining a parallel panel apparatus~\cite{Leventon:NIST_TN_2282}. The panels were 0.6~m (2~ft) wide, 2.4~m (8~ft) tall, and separated by 0.3~m (1~ft). A 60~kW propane sand burner was positioned at the base of the two panels. A sketch of the apparatus, originally developed by Factory Mutual, is shown in Fig.~\ref{Parallel_Panel_Sketch}.
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The Parallel Panel experiment involving black PMMA is part of the suite of cases contributed to the MaCFP (Measurements and Computation of Fire Phenomena) working group of the IAFSS. Its properties are listed in Section~\ref{NIST_Polymers_Properties}.
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