Inlet gap effect on aerodynamics and tonal noise generation of a voluteless centrifugal fan

Ottersten, Martin; Yao, Huadong; Davidson, Lars

doi:10.1016/j.jsv.2022.117304

Cited by 12 publications

(8 citation statements)

References 38 publications

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“…The same finding was also reported in [13]. At the blade-passing frequency (BPF) of voluteless low-speed centrifugal fans, tonal noise is created when turbulence, generated at the gap, interacts with the blade leading edge (BLE) according to previous studies [14,15]. BPF frequencies are usually well above 100 Hz.…”

Section: Introductionsupporting

confidence: 68%

“…The voluteless centrifugal fan and the duct on the fan inlet side are illustrated in Figure 1. The fan is a benchmark that represents most of the characteristics of this type of fan, which has been previously examined in [14,15]. The inlet duct is assembled onto another duct located upstream of it, while the diameter of the inlet duct is smaller than that of the upstream duct.…”

Section: Application Casesmentioning

confidence: 99%

“…With the rotation speed of the fan set to 2800 rpm, the maximum efficiency point occurs at 𝑄 𝐸 = 0.36 kg/s. The operating point (𝑄 𝑂𝑃 ) in this study is the same as in [14,15], where the mass flow rate was 0.467 kg/s, leading to a pressure rise of 269.65 Pa based on the fan characteristic curve in Figure 2. 𝑄 𝑂𝑃 = 1.3𝑄 𝐸 which is a high mass flow rate.…”

Section: Application Casesmentioning

confidence: 99%

“…In an experimental and numerical study on surge [22], it was shown that even at a higher mass flow rate (Q = 1.3Q E ), a periodic lowfrequency pressure fluctuation was detected. It was found that the pressure fluctuations disappeared as the gap was redesigned [15]. However, the physical mechanisms were not discussed in these studies.…”

Section: Introductionmentioning

confidence: 95%

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Inlet Gap Influence on Low-Frequency Flow Unsteadiness in a Centrifugal Fan

2022

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In this study, unsteady low-frequency characteristics in a voluteless low-speed centrifugal fan operating at a high mass flow rate are studied with improved delayed detached eddy simulation (IDDES). This study is motivated by a recent finding that the non-uniformly distributed pressure inside this type of fan could be alleviated by improving the gap geometry. The present simulation results show that the velocity magnitudes of the gap have distinct low and high regions. Intensive turbulent structures are developed in the low-velocity regions and are swept downstream along the intersection between the blade and shroud, on the pressure side of the blade. Eventually, the turbulence gives rise to a high-pressure region near the blade’s trailing edge. This unsteady flow behavior revolves around the fan rotation axis. Additionally, its period is 5% of the fan rotation speed, based on the analysis of the time history of the gap velocity magnitudes and the evolution of the high-pressure region. The same frequency of high pressure was also found in previous experimental measurements. To the authors’ knowledge, this is the first time that the trigger of the gap turbulence, i.e., the unsteady local low velocity, has been determined.

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Section: Introductionsupporting

confidence: 68%

Section: Application Casesmentioning

confidence: 99%

Section: Application Casesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

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Inlet Gap Influence on Low-Frequency Flow Unsteadiness in a Centrifugal Fan

2022

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“…Zhao [11] et al, based on Ansys/Fluent, carried out a relevant study on the effect of the three-dimensional position of the semi-open impeller in the volute on the internal flow field; Kim [12] et al improved the aerodynamic performance by changing the spatial position and shape of the impeller on the basis of CFD analysis of the fan flow field. Ottersten M. [13] et al investigated the effect of different gap geometries on the aerodynamic characteristics of the shell-less centrifugal ventilator based on CFD. The results showed that the turbulence region can be effectively reduced by adjusting the gap geometry.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Impeller Structure Parameters of a Centrifugal Fan in a Powered Air-Purifying Respirator Power System

Zhao,

Guan,

Wang

et al. 2024

Processes

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As the core power element of a centrifugal fan, the impeller’s structural parameters are important factors affecting the aerodynamic performance of the fan. Therefore, to improve the aerodynamic performance of centrifugal fans, in this study, we take the Powered Air-Purifying Respirator (PAPR) power system as the object of research and use a combination of computational fluid dynamics (CFD) and experimental validation to investigate the effects of the number of blades, blade inlet angle, blade outlet angle, blade height, and blade thickness on the aerodynamic performance of the fan. A five-factor, four-level orthogonal test table L16 (45) was selected to obtain the optimal combination of structural parameters for the impeller. In addition, in order to identify and visualize the features of the vortex, Q Criterion Normalized is applied to the simulation on the basis that the minimum pressure appears in the vortex core. In this study, Q Criterion Normalized is used to compare the internal vorticity of the prototype with that of the optimized prototype. The results show that (i) the order of influence of each parameter on the aerodynamic performance of the centrifugal fan is blade height > blade outlet angle > blade inlet angle > number of blades > blade thickness; (ii) the optimal combination of the structural parameters is number of blades 48, blade inlet angle 80°, blade outlet angle 120°, blade thickness 0.6 mm, and blade height 23 mm; the optimized prototype has an increase in air pressure of about 10%, an increase in air volume of about 31%, and an increase in efficiency from 49.61% to 53.57%; (iii) the intensity of internal vortices in the optimized prototype is weakened, the size of vortices and the number of vortices are reduced, and the homogeneity of the flow field is also improved.

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