Variable-speed method for improving the performance of a mine counter-rotating fan

Existing methods of improving the performance of mine counter-rotating fans (MCRFs) through speed matching of the rotors have certain drawbacks. This study proposes a variable-speed method for the two rotors of an MCRF to improve its performance, including the blocking margin, operational safety, high-efficiency working range (HER), and stability margin. Experimental and numerical methods were used to study the pneumatic performance of the MCRF. The results show that the second rotor (R2) is the critical stage affecting the safety of the motor, HER, and blocking margin. A condition-adaptive speed matching method was proposed for R2 to avoid overloading the second motor at low-flow rates and to improve the blocking margin and HER. The first rotor (R1) is the critical stage determining the stability margin of the MCRF. Reducingn(1)and increasingn(2)at low-flow rates helped extend the stability margin.