Study of leakage flow in US underground coal mines

Leakage and air flow resistance in mine auxiliary ventilation ducts: effects on system performance and cost

“…The observations made on the basis of the simulation results, and the formulation of the auxiliary ventilation simulator itself (as set out and exemplified in the Appendix 1) draw upon the basic theory of mine ventilation air flow only; no new theory has had to be developed. The fidelity with which the simulation tool has been applied, to model each individual duct segment joint explicitly within the series–parallel network representation, may be enhanced in comparison to prior approaches where an aggregate Atkinson equivalent leakage resistance (per 100 m length) has been assigned instead, as in Calizaya and Mousset-Jones (1993, 1994, 1997). This may have been made practically possible simply through developments in personal computing power in the intervening two decades.…”

“…A relationship linking the leakage coefficient to a resistance coefficient was also presented, along with criteria that could be used to qualify the amount of leakage in a given system, ranging from good (40,000/ D 2 Ns 2 /m 8 /100 m) to bad (2500/ D 2 Ns 2 /m 8 /100 m), where D represents the duct diameter. A leakage resistance coefficient expressed as Ns 2 /m 8 per 100 m is used in Calizaya and Mousset-Jones (1993, 1994, 1997) as well as in the Ductsim software where it is multiplied by the duct diameter squared to include the effect of duct size (Duckworth and Lowndes 2000, 2003).…”