Ventilation

Ventilation types

The Ventilation tool allows you to place three different types of air vents on the scene:

• Wall vent. Type , key combination Alt + N, Tools | Drawing | Wall vent.

• Floor slab vent. Type , key combination Alt + M, Tools | Drawing | Floor slab vent.

• Jet Fan. Type , Tools | Drawing | Jet Fan.

  The Jet Fan type allows you to direct air flows during fire simulation, giving them additional velocity. As it passes through the fan, the air will retain a number of its properties, such as temperature, smoke concentration, and the presence of chemical components in the air. In raw FDS format, the jet fan will be specified by a group of HVAC parameters. In the topology editor, the fan is displayed as a cylindrical shape, and the direction of air flow through it is shown by a black arrow.

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Placement

The installation of Wall vent and Floor slab vent is carried out by performing the following actions: select the wall/floor slab element in the topology editor, then click the left mouse button to place one or more vent openings. Exit the installation mode by clicking the right mouse button.

For the Wall vent type, installation is only possible on Walls, drawn with the following shapes: straight wall, polyline, rectangle. The walls should be thick enough to cover at least one cell of a Calculation Area.

For the Floor slab vent type, installation is only possible if placed on the Floor slab element.

Jet Fan object can be placed anywhere on the scene. During placement you can: rotate the fan model around the X or Y axis by pressing the space bar; set the air flow direction by pressing the F key; set other object parameters.

Parameters

The following parameters are available for editing:

• Name — the unique name of the placed object.
• Width, Height — the geometric dimensions of the placed object.
• Distance to top, Distance to bottom (Wall Vent only ) — the location of the object relative to the floor level.
• Upper Z, Lower Z (Wall Vent only ) — the upper and lower boundaries of the shape.
• Air Flow — air flow capacity, measured in $m^3/h$.
• Delay time — the time from the start of fire simulation to the moment the fan is activated. If this value is not set and no Detectors are placed in the scenario, ventilation will be activated from the start of fire simulation. If Detectors are placed in the scenario, but the Delay time is not set, ventilation will be activated according to the set Activation delay parameters, even if no detector triggers.
• Activation delay — time of fan activation after the Detectors are triggered. If the Delay time parameter set — ventilation will always activate according to the specified Delay time.
• Lower level from the floor level to the geometric center of the figure.
• Air flow rate — a measure of air flow rate performance. By default, this value is set to $1000 m^3/h$. This field will show the maximum value that ventilation can take if multiple values are set in the working parameters window.
• Base (before installation only ). Install the ventilation element on the inner side of the walls or on the outside .
• Type (Vents only): supply or exhaust.
• Length (Jet Fan only) determines the length of the fan, represented by a horizontally positioned cylinder.
• Radius, Diameter, Area (Jet Fan only) are interdependent values that determine the geometric dimensions of the fan shape in cross-section.
• Level, Z Center (Jet Fan only) are interdependent values that determine the position of the shape relative to the floor level.
• Display object name — toggle to display of the object name in the topology editor.
• Visibility — toggle to display of the object in the topology editor.

Working Parameters

Fenix+ allows you to set a variable operating mode for all types of ventilation or fans. To do this, in the additional Working Parameters window, define timestamps for the time intervals during which the fans will reach the specified air flow rate. For example, these settings allow “acceleration” or “cool down” mode — a gradual increase or decrease in Air flow rate.

To apply these settings, select a ventilation element, look at the right side of your screen, to the object parameters section, and click the Working Parameters.

The Working Parameters window allows you to set the following parameters:

• Start time or Start delay determine when ventilation starts. Changes made in this window will also be reflected in the main list of object parameters.
• Operating time after switching on. Here, you can specify the time marks at which the ventilation should reach the specified Air flow rate values. The full time period being said with these marks and the corresponding air flow value is presented on the right side of the window, in the Graph.

The Graph on the right side of the window displays the configured dynamics of changes in the ventilation mode over time. The graph changes dynamically with the addition or deletion of each timestamp row.

The flow rate for the starting timestamp equals to the value set in object parameters, Air flow rate field, but once you’ve set multiple timpestamps - this value in the object parameters will always show the maximum value set in the Working parameters window.

To Add a timestamp, add a new row by clicking the button, set the moment in time that ventilation air flow should reach the air flow value, specified in the next cell.

Timestamps can be specified in any order — the program will automatically sort them in ascending order when simulating a fire and for display on the graph.

To Delete timestamp, select the row cells and delete the row by pressing the .

To Save the changes you have made, enter values for both cells in a one row. Press Enter to save the changes without closing the settings window. Press to save the changes and start the input for the next timestamp. Press Apply to save the changes and close the settings window.

After completing the changed air flow path, the fan will continue to work with the last provided value. For example, if the fire dynamics simulation time is set to 20 seconds, and the Operating Parameters window for the fan contains a row with values of 5 $s$ and 1000 $m^3/h$, this means that until the 5th second, the flow rate will gradually increase from 0 to 1000 $m^3/h$, and after the 5th second until the 20th, the fan will operate at a flow rate of 1000 $m^3/h$. The graph will show the beginning of the remaining segment as a straight line.