A study on event of unstable operation of an axial fan in a ventilation network

摘要

Unstable operation of a main fan in a ventilation system of an underground coal mine causes transient states of air and gas flow. Such disturbances can have a wide range and a considerable influence on operation of the ventilation system of a mine, and even cause life or health risk for miners. The paper presents the observation of air parameters during unstable operation of the fan-network system at Siemianowice hard coal mine. A reduced network of a mine in a process of closing was fitted with an axial fan. During recording of the fan characteristics, events of flow and pressure oscillations occurred. They not only affected the operation of the fan itself, but also extended over the whole network. A set of measuring devices was installed to investigate these phenomena. Disturbance of flow occurred when the increase of resistance of the inlet damper made the fan operate to the left of the peak of its performance curve. Pulsation had a periodic nature. For some periods the amplitude was stable, then, after a short transient, the flow became steady. The phenomena appeared in a random way. The whole event was recorded with a set of barometers placed in four points of the network and a logger collecting flow and pressure data in vicinity of the fan. An attempt was made to use compressible flow models for computer simulation of the phenomena.