5
return. Air is recirculating near the entry as it enters the
mine. This also shows that when there is no mechanical
ventilation used at the mine, airflow is very low inside the
mine.
Scenario 2: Model with Fan(s) in the Mine
In this scenario, fans were added to the base model with
running them individually and in combination. The fan
size and flowrates were adopted from previous work done
by Grau III and Krog [7]. The location of the fans is shown
in Figure 5. The 3.66-m diameter fan acts as the main ven-
tilation fan in the mine which is 25 m from the mine entry.
This fan was run individually and in combination with
other fans to look at the effectiveness of
In order for better model convergence and resolution
of flows, the mesh elements near the fans were created very
fine. Figure 6 shows the mesh elements around the 3.66-m
diameter fan. The model was run with a 3.66-m diameter
fan in the model, and the velocity profile was plotted along
with streamlines. It can be seen from Figure 7 that plac-
ing a mechanical means to ventilate the mine completely
changes the airflow pattern inside the mine. In comparison
to the velocity profile when no fan was placed in the mine,
the airflow is following the path as observed in the work of
Raj and Gangrade [18] when airflow is entering the mine
entry and following the path of least resistance to get out
of the mine return, even though there is some airflow near
Return 2 but of very low velocity. This means that fresh
air from the inlet is not being utilized by the fan, and due
to recirculation contaminants like diesel particulate mat-
ter (DPM), dust and other engine exhaust concentrations
might increase over time. This is the reason to have fans
operating in combination to maximize ventilation. Grau III
et al. (2002) also suggested that fan placement affects ven-
tilation in large-opening mines. To this end, the two fans
were placed in the mine domain and the combination of
two fans in the model domain were the simulation to look
at their effectiveness.
In order to compare the effectiveness of the simulation
results, four locations were selected in the mine with three
near Return 2 and one at the main return. Figure 8 shows
the sampling locations for calculating the airflow quanti-
ties. Table 1 presents the airflow values at the four locations
as shown in Figure 8. NIOSH also compared the airflow
values from the base case when no mechanical means of
ventilation was used in the first scenario. This is to show
the change in airflow from the case where no fans are used
to the cases when fans are used in the model domain. It can
be clearly inferred from the table that when fans are used
airflow in the mine increases. This increase in airflow quan-
tity is, however, not same with all the fan combinations.
The increase in airflow was mainly visible at the Location 1
(Return 2) with varying airflow at other locations near the
working face. Locations 2 and 3 saw the highest increase
in airflow with a 3.66-m and 2.44-m diameter fan com-
bination in comparison to other fan configurations. These
simulations show that proper fan placement and combina-
tion is needed for better airflow in the regions with low
Figure 5. Fans located in the model domain
return. Air is recirculating near the entry as it enters the
mine. This also shows that when there is no mechanical
ventilation used at the mine, airflow is very low inside the
mine.
Scenario 2: Model with Fan(s) in the Mine
In this scenario, fans were added to the base model with
running them individually and in combination. The fan
size and flowrates were adopted from previous work done
by Grau III and Krog [7]. The location of the fans is shown
in Figure 5. The 3.66-m diameter fan acts as the main ven-
tilation fan in the mine which is 25 m from the mine entry.
This fan was run individually and in combination with
other fans to look at the effectiveness of
In order for better model convergence and resolution
of flows, the mesh elements near the fans were created very
fine. Figure 6 shows the mesh elements around the 3.66-m
diameter fan. The model was run with a 3.66-m diameter
fan in the model, and the velocity profile was plotted along
with streamlines. It can be seen from Figure 7 that plac-
ing a mechanical means to ventilate the mine completely
changes the airflow pattern inside the mine. In comparison
to the velocity profile when no fan was placed in the mine,
the airflow is following the path as observed in the work of
Raj and Gangrade [18] when airflow is entering the mine
entry and following the path of least resistance to get out
of the mine return, even though there is some airflow near
Return 2 but of very low velocity. This means that fresh
air from the inlet is not being utilized by the fan, and due
to recirculation contaminants like diesel particulate mat-
ter (DPM), dust and other engine exhaust concentrations
might increase over time. This is the reason to have fans
operating in combination to maximize ventilation. Grau III
et al. (2002) also suggested that fan placement affects ven-
tilation in large-opening mines. To this end, the two fans
were placed in the mine domain and the combination of
two fans in the model domain were the simulation to look
at their effectiveness.
In order to compare the effectiveness of the simulation
results, four locations were selected in the mine with three
near Return 2 and one at the main return. Figure 8 shows
the sampling locations for calculating the airflow quanti-
ties. Table 1 presents the airflow values at the four locations
as shown in Figure 8. NIOSH also compared the airflow
values from the base case when no mechanical means of
ventilation was used in the first scenario. This is to show
the change in airflow from the case where no fans are used
to the cases when fans are used in the model domain. It can
be clearly inferred from the table that when fans are used
airflow in the mine increases. This increase in airflow quan-
tity is, however, not same with all the fan combinations.
The increase in airflow was mainly visible at the Location 1
(Return 2) with varying airflow at other locations near the
working face. Locations 2 and 3 saw the highest increase
in airflow with a 3.66-m and 2.44-m diameter fan com-
bination in comparison to other fan configurations. These
simulations show that proper fan placement and combina-
tion is needed for better airflow in the regions with low
Figure 5. Fans located in the model domain