Version History

#Version History

##Version 7.0.0 (October 31, 2015)

CFAST and Smokeview are now only available in 64-bit versions. Some older PCs may not be able to run the new versions.

New input file format that includes thermal properties and fire definition in the CFAST input file. Older input files may need to be re-created or at least have a careful review of the fire inputs since the fire inputs have changed significantly (see below) and species yields cannot be automatically update.

Completely updated combustion chemistry routine to a simple combustion of a hydrocarbon fuel that can include carbon, hydrogen, oxygen, chlorine, and nitrogen. The fuel is now a direct user input rather than implied by the ratios in earlier inputs. CO, soot, and trace species yields are now input relative to fuel burned. This will require older input files to be manually edited since the actual fuel composition is not known in an earlier CFAST input file.

Plume entrainment is now based on the Heskestad plume correlations to be consistent with other inputs for flame height and plume temperature. Validation results are slightly closer to experimental results with the Heskestad plume than with the older McCaffrey plume correlation used in earlier versions of CFAST.

Plume temperature and velocity are now calculated off the plume centerline.

Ceiling jet temperature and velocity are now calculated using the Heskestad correlations from the SFPE Handbook. This provides a much simpler calculation than the correlations used in older versions of the model. Validation results are slightly closer to experimental results compared to earlier version of CFAST. A new option for ceiling jet temperature and velocity in corridors is available.

Vent flow now accounts for the buoyancy of gases flowing through a vent. Hotter gases flow to the upper layer of the destination compartment; Cooler gases flow tot he lower layer. Little change in results is obsessed for nearly all test cases.

Calculation of heat transfer to user-specified targets can now include cylindrical targets in addition to plate targets (that use cartesian coordinates). Eliminated thermally thin targets and implicit calculation of target temperature. All targets are now thermally thick with an explicit solution scheme.

Revised calculation of radiative heat flux to targets to better calculate the view factors for the front and back of plate targets.

Corridor flow delay is no longer included in the model. This could have a minor impact on the calculation of detector activation at large distances down a corridor.

Simplified the calculation of convective heat transfer to be consistent with the calculations by FDS. Small changes in target and wall temperatures can be expected.

Changed calculation of point source radiation to be consistent for fires, walls, and targets. All now assume point source is located at 1/3 the flame height, consistent with empirical correlations.

Added the ability to specify compartment surfaces as adiabatic (indicating that no heat is lost by conduction through the surfaces). While this is mainly of used in verifying the model, it does change the results for simulations where surfaces were specified as OFF since this also corrected a bug in the calculation of surface heat exchange for surfaces specified as OFF.

Spreadsheet output has been enhanced to include additional details for door jet fires and target calculations. All species output is now in volume percent/fraction rather than PPM for some species.

Changed default smoke detector characteristics in the GUI to a temperature rise of 10 C and RTI of 5, consistent with NRC NUREG 1805.

Smokeview was updated to version 6.3.1, consistent with current FDS release version. This includes new vent flow visualization, slice files that can show 3-D temperature and velocity within compartments, and isosurfaces of constant temperature within compartments. Only visualization of door and window vent flows are included at the moment. Visualization for floor/ceiling vents and mechanical vents will be included in a future release.

Fixed an error in the calculation of layer absorptivity where the calculation was using unburned hydrocarbon concentration rather than water concentration. Small changes in gas, wall, and target temperature can be expected.

Fixed an error in the initialization of relative humidity for the outside.

Fixed an error in wall and corner entrainment where radiation would go to infinity at the wall resulting in a crash for some test cases.

Corrected an error loading certain files. The first listed detector RTI and activation temperature was set to default values for detectors. For some input files, thermal properties of the first compartment could be reset to OFF in the GUI on reading the file.

Corrected an error in the calculation of trace species filtering in mechanical ventilation systems where the systems had fans flowing in both directions between a pair of compartments (two fans flowing in opposite directions).

Updated the entire CFAST code to Fortran 2008.

Completely revised verification test cases and added numerous additional validation cases to the test suite. Automated the testing of model V&V consistent with the processes used for FDS.

Completely new documentation now in LaTeX to facilitate editing and to automate document creation.

##Version 6.2.0 (October 31, 2011)

Added plume centerline temperature calculation from work of McCaffrey, Heskestad, and Evans. This is now used for the surrounding gas temperature for target calculations. Note that at this point, it only impacts targets directly over a fire source.

Updated spreadsheet column headings to be more readable and useful, including units. This also added the option for a net heat flux output (now the default) for all target heat flux outputs.

Added cylindrical targets largely aimed at improving calculation of heat flux to and temperature of wire and cable targets.

General code cleanup, verification, and validation. This included removal of numerous unused variables that were left over from earlier features long since removed from the model. Code logic analysis with Forcheck to ensure call and variable consistency, additional and repeated validation tests.

Added detailed discussion of CFAST's fire chemistry and target calculations to Technical Reference Guide. Updated User's Guide and Validation Guide for latest version.

##Version 6.1.1 (Febrary 4, 2009)

Added a new species, labeled TS, to track flow through compartments. TS is a trace species produce during pyrolysis and is not affected by combustion. The assumption is that molecules are large enough to be filtered, but that mass is small compared to the overall pyrolysis. See NISTIR 7498 for an example of its use.

Added the ability to specify filtering for mechanical ventilation systems which applies to soot and the trace species. For the user, it is implemented wtih the EVENT,F command and available through the GUI. See the Userís Guide, NIST Special Publication 1041 (May 2008 Revision) for details.

Separated pyrolysis and combustion kinetics. The original purpose was to fix a bug related to pyrolysis products not being transported to the upper layer when a fire is only in the upper layer. The code was structured so that a consistent combustion model for a plume could be implemented. Species affected only by pyrolysis are hydrogren choloride, hydrogen cyanide, trace species and the concentration time product. Species affected only by kinetics are carbon-dioxide, carbon-monoxide, and soot. Species affected by both are oxygen and fuel. Nitrogen is inert and only transported.

Corrected error in mechanical ventilation that prevented flow from dropping off at high pressures like it was supposed too. An additional error casued DASSL to fail at times when the mechanical ventilatino system shut off due to (the now corrected) high pressure cutoff. The solution was to not totally close the vent (the vent is left open at an extremely small value, machine epsilson for double precision) Corrected error in exehandle routine that caused model to fail with path names longer than 128 characters (windows limit is 255 characters for whole file name). Corrected error in interpolation routines for opening and closing vents that did not smoothly transistion from open to closed (Since the GUI did this over 1 s, the impact should not be noticeable for previously run cases).

Incorporated Heskestad plume model as an alternative to the McCaffrey plume model (type 2). There is a small difference in the calculated results for a range of test cases (on the order of 2% to 4%). The plan is to add plume temperature to the calculation as well.

Smokeview updated to improve visualization of vent flows (now accounts for vent opening and closing) and smoke (3-D smoke visualization now an option that depends on calculation optical density).

Corrected error in the GUI that incorrectly outputs the mechanical ventilation specification for the CFAST model. The fifth parameter on the line specifies a "system number" for each mechanical ventilation system. In older versions, this began with 1 for each compartment rather than being numbered sequentially throughout. The impact was that opening and closing of vents would not work when there were mechanical ventilation fans in more than one compartment. Calculation was correct for fully-opened mechanical vents.

##Version 6.0.10 (January 11, 2007)

Beginning with version 6.0.10, CFAST and CEdit were compiled with Visual Studio 2005. This means that both new and existing users of earlier versions of the Windows CFAST will need to download and install Microsoft .NET version 2.0 (included in the larger download of CFAST) if it is not already installed on their computer.

Corrected subscript error in cfast input checking for ceiling-floor conduction connections that caused an error with simulations with 5 or more compartments. Corrected an error in the definition of fire objects to allow radiative fraction to be zero, not just greater than zero. Corrected a display error for CFAST files in smokeview that placed fires in the wrong compartment for visualization; calculations, spreadsheet, and printed output were correct.

Updated the GUI to Visual Studio 2005, including spreadsheet, auto-sizing, and preview libraries. Reversed order of CFAST log file in the message summary so that any errors would appear at the top of the list, more visible to the user. Changed limit on number of mechanical ventilation connections from 10 to 100. Corrected an error that prevented saving of an input file when compartments were removed from a simulation. Corrected an error that caused incorrect values for default fire position when engineering units were not set to m. Fixed compartment naming when a compartment is duplicated. Corrected an error when defining a new fire that did not assign a material to the fire (leading to an error 205 when running CFAST). Enabled RTI input for heat alarms (Previously, heat alarms were presumed to have a default value for the RTI). Corrected a subscript error that caused GUI error message for a compartment specified as a single zone if the compartment was the highest numbered compartment in the simulation.

Added the ability to define a general t-squared growth rate fire to the Edit Fire Objects window, allowing the user to select growth rate, peak HRR, steady burning time, and decay time, including predefined constants for slow, medium, fast, and ultra-fast t-squared fires. Added the ability to add and remove thermal properties on the thermal properties edit window. Redesigned the heat transfer connection tab to separate horizontal and vertical heat transfer specifications to allow for future enhancement of the horizontal connections to better support the HHEAT keyword in CFAST; for the moment, only a single, fractional connection is allowed on a given keyword line. Note that vertical heat transfer always assumes a fraction of one for the connection.

##Version 6.0.9 (May 15, 2006)

Corrected error in CFAST where ignition time of a fire was off by 1 s when specified ignition time was t = 0 s.

Corrected error in specification of alternate thermal property files that would not allow reading of the alternate files nor set file changed flag when file was changed. Corrected links to GUI text boxes for HCl constants 2 through 7 that prevented editing of these constants. Corrected size of summary spreadsheets in the GUI to be consistent with CFAST design limits. This would cause the program to crash if you had more than 50 vents or targets in a single simulation. Heat source fire on Fires tab was not actually implemented in the model; this has been removed from the GUI. Corrected units in the GUI for HCl and HCN. They were listed as kg/s by default rather thankg/kg (dimensionless). This would lead to incorrect species yields for simulations with user selected units other than kg for mass and s for time.

##Version 6.0.8 (February 28, 2006)

Corrected errors in the calculation of unburned fuel that caused the fuel not to burn in compartments remote from the fire room. Ignition temperature for doorway fires is now a global parameter that is entered on the Fires tab of the input program.

Beginning with version 6.0.8, default installation locations for program files and user data files follow the Windows model so that executable files are typically located in "C:\Program Files\CFAST" and user data files are located in "MyDocuments\CFASTData." If upgrading from an earlier version of the software, the installation program removes older executable files, but leaves existing data files in their original location. If desired, the files can be moved to the new data directory created during installation of the software.

##Version 6.0.7 (February 1, 2006)

Corrected an error in the horizontal flow routine that prevented printout of vent flow values for some vents

Corrected error in the GUI where corridor flow coefficients were incorrectly assigned a default value of 0 rather than the CFAST assumed value of -1. This caused erroneous calculation of corridor flows allowing excessive temperatures in hallways to be calculated.

##Version 6.0.5 (October 1, 2005)

Add target normal calculation to cedit, and extend object plotting in GUI to all object variables. Add error checking for objects and detectors placed outside of a compartment. Fix ceiling jet coordinates so that they agree with targets.

An inconsistent labeling of width, depth and height caused incorrect target flux calculations.

The initial/final open fraction for vertical flow and mechanical flow were not being set correctly. Both have been fixed.

The ambient flux calculations seem to be too high. The problem lies in specification of object properties. The fire has to release energy over a finite volume. As the size of this volume is reduced, the energy per unit volume goes up and thus the heat flux rises. There is a physical limit on the maximum such energy release per unit volume. As pointed out by Orloff and deRis ("Froude Modeling of Pool Fires," Factory Mutual Technical Report OHON3.BU, Norwood (1983)), there is a physical limit on the maximum such energy release per unit volume. This limitation arises because mixing and diffusion take a finite amount of time, and radiation is limited by optical depth, at least for fires of the sort we consider in CFAST, namely buoyant diffusion flames. The upper limit is 1.2 MW/m3. An object model which is the area of the object as defined in the database (.o) and the height extent which includes a maximum flame length is used to make this estimate. The input routine, INPUTOBJECT, does this calculation, with a warning at 2 MW/m3, and a stop with the error code 221 at 4 MW/m3. The minimum object volume is now 1.0x10-6 m3.

##Version 6.0.1 (June 1, 2005)

Initial release of version 6 of CFAST, including a Windows version of the CEdit graphical user interface. Fires are now treated as objects, which can be placed and sized within compartments. Mechanical ventilation has been simplified to fan/opening pairs, and all vents (vertical flow, horizontal flow and forced flow) can be turned off or on (single instance).