Fans and Auxiliary Ventilation

This set of vocabulary flashcards covers types of mine fans, mechanical designs, fan pressure definitions, characteristic curves, fan laws, and fan combinations based on the lecture notes.

Main fans

Fans that handle all of the air passing through the underground mine.

Booster Fans

Fans used to assist the through-flow of air in discrete areas of the mine.

Auxiliary Fans

Fans designed to provide air to blind headings.

Centrifugal Fans

Fans characterized by a collection scroll or volute, an impeller with blades, and a suction eye; they are generally more reliable than axial fans.

Axial Fans

Compact fans with a single stage limit of $5\,kPa$ and motors often located in the air stream; they are prone to severe stall.

Mixed Flow Fans

A type of fan mechanical design that incorporates both blades and guide vanes.

Fan Total Pressure ($TP_{fan}$)

The difference between the total pressure at the outlet and the total pressure at the inlet ($TP_{out} - TP_{in}$).

Fan Velocity Pressure ($VP_{fan}$)

The velocity pressure measured at the fan outlet ($VP_{out}$).

Fan Static Pressure ($SP_{fan}$)

Calculated as $TP_{fan} - VP_{fan}$, which expands to $TP_{out} - TP_{in} - VP_{out}$.

Stall Point

The point on a fan characteristic curve that marks the beginning of the stall zone, where airflow becomes unstable.

Air Power

The power of the air calculated by the formula $\frac{P \times Q}{1000}\,kW$, where $P$ is pressure in $Pa$ and $Q$ is air quantity in $m^3/s$.

Fan Efficiency ($\eta$)

The ratio of Air Power to Consumed Power, expressed as a percentage: $\frac{\text{Air Power}}{\text{Consumed Power}} \times 100\%$.

Fan Operating Point

The point determined by the intersection of the fan characteristic curve and the circuit resistance curve.

Fan Law: Speed and Quantity

States that air quantity ($Q$) is directly proportional to fan speed ($n$): $\frac{Q_1}{Q_2} = \frac{n_1}{n_2}$.

Fan Law: Speed and Pressure

States that pressure ($P$) is proportional to the square of the fan speed ($n$): $\frac{P_1}{P_2} = (\frac{n_1}{n_2})^2$.

Fan Law: Speed and Power

States that power ($E$) is proportional to the cube of the fan speed ($n$): $\frac{E_1}{E_2} = (\frac{n_1}{n_2})^3$.

Fan Law: Density and Pressure

States that pressure ($P$) is directly proportional to air density ($\rho$): $\frac{P_1}{P_2} = \frac{\rho_1}{\rho_2}$.

Fans in Series

A combination where the same quantity ($Q$) passes through both fans and the total pressure is the sum of each fan's individual pressure.

Fans in Parallel

A combination where the pressure drop across both fans is the same and the total air quantity is the sum of each fan's quantity ($Q = Q_A + Q_B$).

Natural Ventilation Pressure (NVP)

A naturally occurring pressure that adjusts the mine's resistance curve, expressed as $P = R \times Q^2 - NVP$.