Performance, aeroacoustics and feature extraction of an axial flow fan with abnormal blade angle

Energy ◽  
2016 ◽  
Vol 103 ◽  
pp. 322-339 ◽  
Author(s):  
Chunxi Li ◽  
Qing Lin ◽  
Xueliang Ding ◽  
Xuemin Ye
Author(s):  
Michael B. Wilkinson ◽  
Sybrand J. van der Spuy ◽  
Theodor W. von Backström

An axial flow fan developed in the previous study is tested in order to characterize its performance. The M-fan, a 7.3152 m diameter rotor only axial flow fan was designed to perform well under the challenging operating conditions encountered in air-cooled heat exchangers. Preliminary computational fluid dynamics (CFD) results obtained using an actuator disk model (ADM) as well as a periodic three dimensional model indicate that the fan meets the specified performance targets, with an expected total-to-static efficiency of 59.4% and a total-to-static pressure rise of 114.7 Pa at the operating point. Experimental tests are performed on the M-fan in order to determine its performance across a full range of flow rates. A range of fan configurations are tested in order to ascertain the effect of tip clearance, blade angle, and hub configuration on fan performance. Due to the lack of a suitable facility for testing a large diameter fan, a scaled 1.542 m diameter model is tested on the ISO 5801 type A fan test facility at Stellenbosch University. A Reynolds-averaged Navier–Stokes CFD model representing the M-fan in the test facility is also developed in order to provide additional insight into the flow field in the vicinity of the fan blades. The results of the CFD model will be validated using the experimental data obtained. Both the CFD results and the experimental data obtained are compared to the initial CFD results for the full scale fan, as obtained in the previous study, by means of fan scaling laws. Experimental data indicate that the M-fan does not meet the pressure requirement set out in the initial study at the design blade setting angle of 34 deg. Under these conditions, the M-fan attains a total-to-static pressure rise of 102.5 Pa and a total-to-static efficiency of 56.4%, running with a tip gap of 2 mm. Increasing the blade angle is shown to be a potential remedy, improving the total-to-static pressure rise and efficiency obtained at the operating point. The M-fan is also shown to be highly sensitive to increasing tip gap, with larger tip gaps substantially reducing fan performance. The losses due to tip gap are also shown to be overestimated by the CFD simulations. Both experimental and numerically obtained results indicate lower fan total-to-static efficiencies than obtained in the initial CFD study. Results indicate that the M-fan is suited to its intended application, however, it should be operated with a smaller tip gap than initially recommended and a larger blade setting angle. Hub configuration is also shown to have an influence on fan performance, potentially improving performance at low flow rates.


Author(s):  
Michael B. Wilkinson ◽  
Johan van der Spuy ◽  
Theodor W. von Backström

An axial flow fan developed in previous study is tested in order to characterise its performance. The M-fan, a 7.3152 m diameter rotor only axial flow fan was designed to perform well under the challenging operating conditions encountered in air-cooled heat exchangers. Preliminary CFD results obtained using an actuator disk model as well as a periodic three dimensional model indicate that the fan meets the specified performance targets, with an expected total-to-static efficiency of 59.4 % and a total-to-static pressure rise of 114.7 Pa at the operating point. Experimental tests are performed on the M-fan in order to determine its performance across a full range of flow rates. A range of fan configurations are tested in order to ascertain the effect of tip clearance, blade angle and hub configuration on fan performance. Due to the lack of a suitable facility for testing a large diameter fan, a scaled 1.542 m diameter model is tested on the BS 848 (ISO 5801) type A fan test facility at Stellenbosch University. A RANS CFD model representing the M-fan in the test facility is also developed in order to provide additional insight into the flow field in the vicinity of the fan blades. The results of the CFD model will be validated using the experimental data obtained. Both the CFD results and the experimental data obtained are compared to the initial CFD results for the full scale fan, as obtained in the previous study, by means of fan scaling laws. Experimental data indicates that the M-fan does not meet the pressure requirement set out in the initial study, at the design blade setting angle of 34 degrees. Under these conditions the M-fan attains a total-to-static pressure rise of 102.5 Pa and a total-to-static efficiency of 56.4%, running with a tip gap of 2 mm. Increasing the blade angle is shown to be a potential remedy, improving the total-to-static pressure rise and efficiency obtained at the operating point. The M-fan is also shown to be highly sensitive to increasing tip gap, with larger tip gaps substantially reducing fan performance. The losses due to tip gap are also shown to be overestimated by the CFD simulations. Both experimental and numerically obtained results indicate lower fan total-to-static efficiencies than obtained in the initial CFD study. Results indicate that the M-fan is suited to its intended application, however it should be operated with a smaller tip gap than initially recommended and a larger blade setting angle. Hub configuration is also shown to have an influence on fan performance, potentially improving performance at low flow rates.


2014 ◽  
Vol 1065-1069 ◽  
pp. 2141-2146
Author(s):  
Yuan Yuan Li ◽  
Zhen Ning Zhao ◽  
Zhi Qiang Wen

Based on the axial-flow fan with adjustable vanes in a power plant of Tangshan, the internal flow with different inlet speeds during the axial-flow fan run were simulated with FLUENT software package. The results showed that if inlet velocity was greater than the critical velocity, the flow was relatively uniform. If inlet velocity was lower than the critical velocity, a vortex caused by tip leakage would decrease fan efficiency and induce surge.The impact increased gradually with increasing of the moving blade angle. The results were consistent with the actual and provided further evidence for high efficient and safe operation of axial-flow fans.


2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Nobuyuki Yamaguchi ◽  
Masayuki Ogata ◽  
Yohei Kato

An improved construction of air-separator device, which has radial-vanes embedded within its inlet circumferential opening with their leading-edges facing the moving tips of the fan rotor-blades so as to scoop the tip flow, was investigated with respect to the stall-prevention effect on a low-speed, single-stage, lightly loaded, axial-flow fan. Stall-prevention effects by the separator layout, relative location of the separator to the rotor-blades, and widths of the openings of the air-separator inlet and exit were parametrically surveyed. As far as the particular fan is concerned, the device together with the best relative location has proved to be able to eliminate effectively the stall zone having existed in the original solid-wall characteristics, which has confirmed the promising potential of the device. Guidelines were obtained from the data for optimizing relative locations of the device to the rotor-blades, maximizing the stall-prevention effect of the device, and minimizing the axial size of the device for a required stall-prevention effect, at least for the particular fan and possibly for fans of similar light-load fans. The data suggest the changing internal flow conditions affected by the device conditions.


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