**3.14 Finding 14: regulators and cave footprint changes the cave resistance**

This study investigated the effects of cave footprint, and regulators on the cave airflow resistance. Regulators were able to distribute airflow rates through the caved zone and extraction drifts. Bends and regulators made it challenging to obtain constant air velocity within the ducts.


**Table 8.** *Average values of exponent* n*.*


### **Table 9.**

*Average values of exponent* n *with the top fan.*

Both the experimental and CFD simulation results demonstrated (**Figure 31**) that the increment of porosity and particle size in the caved materials increases the area available for flow within the cave (decreased airflow resistance) and increased airflow distribution percentage through the cave system under a given regulator combination. The shrinkage/reduction of cave footprint decreases the area available for flow within the cave (increased cave airflow resistance) significantly. The use of regulators increased the fan head pressure, decreased the overall airflow rate, and changed the distribution of airflow rates through the cave system and extraction drifts. The increase of airflow rate through the system is favorable for gas dilution regardless of the source locations; while the regulated airflow system might deteriorate gas dilution performance, especially when the source is located at the extraction level (**Tables 10** and **11**).
