In this study, we tried to improve the performance by giving a pre-swirling flow to the radial inflow that occurred in the semi-opened axial fan. In addition, the flow fields of rotor outlet were clarified experimenta...In this study, we tried to improve the performance by giving a pre-swirling flow to the radial inflow that occurred in the semi-opened axial fan. In addition, the flow fields of rotor outlet were clarified experimentally, and the effect of pre-swirling flow was considered. The experiment was carried out using a performance test wind tunnel with a square cross section of 880 mm. Three types of casings were prepared, in which the blade tip protruded 0%, 20%, and 40% of the meridional chord length. They were called R25, R15, and R05, respectively, in the casing bellmouth model code. Guide blades for generating a pre-swirling flow were installed on the vertical wall surface of the casing. In addition, a vertical wall was installed 60% upstream of the meridional chord length as an obstacle to prevent axial inflow. The velocity fields of the rotor outlet were measured using a hot-wire anemometer. From the results, the pre-swirling flow did not significantly affect the fan performance. When there was no obstacles wall upstream, there was a partial increase in efficiency, but the difference was not so large. When there was an obstacle wall upstream, the efficiency increased overall in the case of R15, but in the case of R05, the efficiency increased only in the low flow rate region, and conversely decreased in the high flow rate region. By observing the blade outlet flow fields when the performance was improved, it was confirmed that the influence of the tip leakage vortex was weakened.展开更多
Mines are continually expanding in size and depth,leading to an increased reliance on localised subsurface ventilation systems.The use of underground auxiliary fans is a favoured method to increase and control airflow...Mines are continually expanding in size and depth,leading to an increased reliance on localised subsurface ventilation systems.The use of underground auxiliary fans is a favoured method to increase and control airflow in working areas.However,the effectiveness of auxiliary fans in this regard is not clear.This paper evaluated the performance of these underground fan systems in four different South African deeplevel gold mines.A total auxiliary fan system efficiency of 5%was found across six systems,with the average fan efficiency of 33 fans at 38%.The results showed that these fans deviate significantly from their design operating points.Therefore,there are significant shortcomings in current underground fan practices.Our detailed investigations led to the conclusion that the assemblage of underground auxiliary fan systems results in significant energy inefficiencies.Therefore,maintaining good underground fan practice such as optimal fan selection,ducting design and maintenance is crucial for the efficacy of a mine ventilation network.展开更多
文摘In this study, we tried to improve the performance by giving a pre-swirling flow to the radial inflow that occurred in the semi-opened axial fan. In addition, the flow fields of rotor outlet were clarified experimentally, and the effect of pre-swirling flow was considered. The experiment was carried out using a performance test wind tunnel with a square cross section of 880 mm. Three types of casings were prepared, in which the blade tip protruded 0%, 20%, and 40% of the meridional chord length. They were called R25, R15, and R05, respectively, in the casing bellmouth model code. Guide blades for generating a pre-swirling flow were installed on the vertical wall surface of the casing. In addition, a vertical wall was installed 60% upstream of the meridional chord length as an obstacle to prevent axial inflow. The velocity fields of the rotor outlet were measured using a hot-wire anemometer. From the results, the pre-swirling flow did not significantly affect the fan performance. When there was no obstacles wall upstream, there was a partial increase in efficiency, but the difference was not so large. When there was an obstacle wall upstream, the efficiency increased overall in the case of R15, but in the case of R05, the efficiency increased only in the low flow rate region, and conversely decreased in the high flow rate region. By observing the blade outlet flow fields when the performance was improved, it was confirmed that the influence of the tip leakage vortex was weakened.
基金ETA Operations (Pty) Ltd funded this research work
文摘Mines are continually expanding in size and depth,leading to an increased reliance on localised subsurface ventilation systems.The use of underground auxiliary fans is a favoured method to increase and control airflow in working areas.However,the effectiveness of auxiliary fans in this regard is not clear.This paper evaluated the performance of these underground fan systems in four different South African deeplevel gold mines.A total auxiliary fan system efficiency of 5%was found across six systems,with the average fan efficiency of 33 fans at 38%.The results showed that these fans deviate significantly from their design operating points.Therefore,there are significant shortcomings in current underground fan practices.Our detailed investigations led to the conclusion that the assemblage of underground auxiliary fan systems results in significant energy inefficiencies.Therefore,maintaining good underground fan practice such as optimal fan selection,ducting design and maintenance is crucial for the efficacy of a mine ventilation network.
