1. A tunnel in a mine is 620 m in length and has a cross-sectional area of 24 m2 and a perimeter of 20 m. If the friction factor for the airway is 0.014 kg/m3, determine the resistance of the airway.
2. A straight 5 x 4.5 m mine tunnel is 970m in length. If this tunnel is roughly blasted, determine the resistance of the tunnel. If 70 m3 /s of air is passed along this tunnel what would be the pressure drop along the tunnel.
3. A straight 5 x 5 m tunnel is 1200m in length and is lined with shotcrete, determine the airway resistance.
4. Measurements from a ventilation survey indicate that along a particular tunnel a pressure drop of 0.15 kPa for a flow of 35m3/s. If the tunnel is 604m in length and is a 4.5 x 4.5m airway what is the friction factor of the tunnel?
5. A 5 x 4.5 m rectangular tunnel is 950m in length and contains a single right angled bend with a centre-line radius of curvature of 3.5m. The tunnel is unlined but is in good condition with the major irregularities having been trimmed away. The tunnel is required to pass 80 m3/s of air with a density of 1.25 kg/m3. Calculate the airway resistance and the frictional pressure drop.
4. Determine the equivalent length for a sudden contraction in a mine airway from a cross-sectional area of 20 m2 to 15m2 assuming that the perimeter of the airway remains unchanged at 16m. Assume k = 0.01 kg/m3.
5. Two mine airways with resistances of 0.5 Ns2/m8 and 1.1 Ns2/m8 are connected in series determine the resistance of the series combination. If the airflow through these airways is 37 m3/s, what is the pressure drop in each of the airways and the total pressure drop in the series combination of airways?
6. Three mine airways with resistances of 0.5 Ns2/m8, 0.4 Ns2/m8and 1.2 Ns2/m8 are connected in series determine the resistance of the series combination. If the airflow through these airways is 54 m3/s, what is the pressure drop in each of the airways and the total pressure drop in the series combination of airways?
7. Two mine airways with resistances of 1.7 and 1.1 Ns2/m8 are connected together in parallel. Determine the resistance of the parallel combination. If 35 m3/s flows into this parallel combination of airways determine the flow in each airway.
8. For the ventilation network shown below, determine the flow and pressure drop in each branch of the network.
