A Critical Review of Passive Noise Control Techniques in Industrial Fans

Bianchi, Stefano; Corsini, Alessandro; Sheard, Anthony G.

doi:10.1115/1.4025837

Cited by 14 publications

(5 citation statements)

References 52 publications

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“…It was then attempted to reduce this phenomena by means of a hollow blade, where ow is entrained near the blade root on the pressure side by the centrifugation of the volume inside the blade and ejected at the trailing edge in the tip region. A similar technique to control separation and noise in fans is also reported by Bianchi et al (2014), but not applied to a specic fan. In the case of Eberlinc et al (2009) a small increase in both pressure dierence and peak total eciency (∆η F t ≈ 5 %) was noted.…”

Section: Arbitrary Fan Modicationsmentioning

confidence: 99%

Investigation of the Flow Field in the Vicinity of an Axial Flow Fan During Low Flow Rates

Louw

Backström

Spuy

2014

Volume 1A: Aircraft Engine; Fans and Blowers

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Large axial flow fans are used in forced draft air cooled heat exchangers (ACHEs). Previous studies have shown that adverse operating conditions cause certain sectors of the fan, or the fan as a whole to operate at very low flow rates, thereby reducing the cooling effectiveness of the ACHE. The present study is directed towards the experimental and numerical analyses of the flow in the vicinity of an axial flow fan during low flow rates. This is done to obtain the global flow structure up and downstream of the fan. A near-free-vortex fan, designed for specific application in ACHEs, is used for the investigation. Experimental fan testing was conducted in a British Standard 848, type A fan test facility, to obtain the fan characteristic. Both steady-state and time-dependent numerical simulations were performed, depending on the operating condition of the fan, using the Realizable k-ε turbulence model. Good agreement is found between the numerically and experimentally obtained fan characteristic data. Using data from the numerical simulations, the time and circumferentially averaged flow field is presented. At the design flow rate the downstream fan jet mainly moves in the axial and tangential direction, as expected for a free-vortex design criteria, with a small amount of radial flow that can be observed. As the flow rate through the fan is decreased, it is evident that the down-stream fan jet gradually shifts more diagonally outwards, and the region where reverse flow occur between the fan jet and the fan rotational axis increases. At very low flow rates the flow close to the tip reverses through the fan, producing a small recirculation zone as well as swirl at certain locations upstream of the fan.

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Section: Arbitrary Fan Modicationsmentioning

confidence: 99%

Investigation of the Flow Field in the Vicinity of an Axial Flow Fan During Low Flow Rates

Louw

Backström

Spuy

2014

Volume 1A: Aircraft Engine; Fans and Blowers

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“…The adoption of concepts that are biology-inspired is not entirely novel in turbomachinery design. These solutions frequently aim to increase stall margin, lift-to-drag maximization, and noise emission reduction [16]. Pioneering works from Fish [17,18] focus on hydro-dynamics and how natural selection has favored characteristics that improve swimming efficiency.…”

Section: Flow Control Using Sinusoidal Leading Edgesmentioning

confidence: 99%

“…In particular, the aim is to limit the trailing edge separation that occurs at peak pressure to allow the tip leakage vortex to develop along the suction side of the blade. Breaking the interaction of flow separation with the TLV allows for its development along the blade suction side and, thus, avoids the drop in pressure typically associated with stalled operations [16]. This dynamic is shown in Figure 3, where the streamlines of relative velocity on a cylindrical surface at 100.05% of the tip radius are plotted with the tip in the background as a reference.…”

Section: Design Of Sinusoidal Leading Edge Rotor For a Low-speed High...mentioning

confidence: 99%

Design of Sinusoidal Leading Edge for Low-Speed Axial Fans Operating under Inflow Distortion

Tieghi,

Delibra,

Van der Spuy

et al. 2024

Energies

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Axial fans may be equipped with passive flow control devices to enhance rotor efficiency or minimize noise emissions. In this regard, blade designs influenced by biomimicry, such as rotors with sinusoidal leading edges (LEs), have gained popularity in recent years. However, their design is predominantly driven by a trial-and-error approach, with limited systematic studies on the influence of rotor performance. Furthermore, their effectiveness is typically evaluated under controlled conditions that may significantly differ from operations in real installation layouts. In this work, a systematic review of the design process for sinusoidal LE axial fan rotors is provided, aiming to summarize previous design experiences. Then, a modified sinusoidal LE is designed and fitted to a 7.3 m low-speed axial fan for air-cooled condensers (ACCs). These fans operate at environmental conditions, providing a quasi-zero static pressure rise, often with inflow non-uniformities. A series of RANS computations were run to simulate the performance of the baseline fan and that of the sinusoidal leading edge, considering a real installation setup at Stellenbosh University, where the ACC is constrained between buildings and has a channel running on the ground below the fan inlet. The aim is to explore the nonbalanced inflow condition effects in both rotor geometries and to test the effect of the installation layout on fan performance. The results show that the modification to the rotor allows for a more even distribution of flow in the blade-to-blade passages with respect to the baseline geometry.

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“…The airfoil self-noise is associated with the turbulent flow that develops in the boundary layers of the fan blades and OGV. Self-noise has been shown to be a significant noise source in many applications, such as wind turbines [5], low speed ventilation fans [6] and aero-engines [7], and has been the motivation for several studies [8,9,10].…”

Section: Introductionmentioning

confidence: 99%