Abstract
Axial fans play a pivotal role in the road tunnel ventilation system. Qualified performance of the axial fan is important for both safety and air quality maintenance reasons. Axial fans performance in situ test of Qinling Zhongnan Mountain highway tunnel, the second longest road tunnel in the world, is presented in this research. Performance test items and the qualification criterion, as well as a general framework for the road tunnel axial fan assessment, are recommended. Log-Tchebycheff method is suggested to confirm the location for the measuring lines and points. The precision of the log-Tchebycheff method in air flow rate measuring is verified by comparing with the biharmonic spline interpolation fitting result. The research shows that the log-Tchebycheff method has high precision and good efficiency in the air flow rate measurement of the road tunnel air duct. What is more, the biharmonic spline interpolation fitting method can be applied to obtain a more accurate result. The number of interpolation points of the biharmonic spline interpolation fitting method should be bigger than 2000 to provide quality results.
Highlights
Ventilation plays a critical role in both normal operating [1] and fire [2, 3] situations of a tunnel
Axial fans and jet fans constitute the main part of the tunnel ventilation system
Indoor or numerical researches on jet fans preference are extensively established [9,10,11,12,13,14,15]. It is generally diagnosed by comparing the fan performance curve provided by the fan manufacturer with the required performance parameters of the designed tunnel
Summary
Ventilation plays a critical role in both normal operating [1] and fire [2, 3] situations of a tunnel. The cross-section area of the tunnel air duct is usually two to three times than that of the mine air duct and is always much shorter For these reasons, the wind field of road tunnel air duct is more disordered which brings difficulty to the precision measurement of the air flow rate. The air velocity method can provide the air flow rate directly and is extensively applied in fan performance in situ tests. A five-point truss was utilised by Levoni et al [28] to investigate the fluid dynamic characterisation of the Mont Blanc tunnel These simultaneous multipoint velocity measurements constitute the available method for collecting reliable mean air velocity data along a tunnel’s cross section and estimating the total flow rate. The performance of the axial fan of the tunnel is assessed via performance curves established by the in situ result
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