Reduction of the Aerodynamic Tonal Noise of a Forward-Curved Centrifugal Fan by Modification of the Volute Tongue Geometry

́rez, Sandra Velarde-Sua; Ballesteros-Tajadura, Rafael; Santolaria-Morros, Carlos; ́a, Bruno Pereiras-Garci

doi:10.1115/fedsm2005-77436

Cited by 11 publications

(14 citation statements)

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“…The two parts are mounted producing a shift of the 23 blades, so that the mechanical resonances are minimized. However, it has been reported both experimental and numerically [3,20] that due to the different aspirating conditions for both parts, a 60%-40% ratio in the flow rate distribution is observed in the impeller outlet, thus providing a non-symmetric flow. The main geometrical variables and working parameters at the nominal conditions are shown in Table 1, for a rotational speed of 3600 rpm.…”

Section: -Machine Descriptionmentioning

confidence: 99%

“…Typically, the poor design of the flow channel in these fans causes a severely distorted primary flow [2], with early flow separation on the suction side at both low and design flow rates. It is also well-known the inefficiencies of these machines to the sharp axial to radial bend, the large inlet gap between inlet nozzle and impeller shroud and the poor matching between impeller outlet and volute tongue [3].…”

Section: -Introductionmentioning

confidence: 99%

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Numerical methodology for the assessment of relative and absolute deterministic flow structures in the analysis of impeller–tongue interactions for centrifugal fans

et al. 2013

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In this paper a numerical methodology to segregate relative and absolute flow structures, allowing a deep analysis of the impeller-tongue interaction in centrifugal fans, is presented. The procedure, based on a deterministic decomposition of the internal flow fields, is applied for first time in blade-to-blade planes of radial turbomachinery. Previous numerical results, obtained with a viscous 3D unsteady solver, already validated by the authors and available in the literature, are used as a database for the numerical routines. Interpolation and relocating operations of the velocity fields between CFD meshes and post-processing grids are presented and performed for different flow rates of a squirrel cage fan. This numerical technique is shown as an ideal framework to advance in the physical comprehension of the complexity, three-dimensionality and unsteadiness of the flow structures in the interaction regions of centrifugal fans. Additionally, the different contributors to the unsteady forces on the blades are also addressed, providing a valuable insight to identify the origin of the interaction phenomena for both diagnosis and redesign criteria of impeller and volute geometries. The squirrel cage fan studied is a small centrifugal fan with a twin impeller configuration, each with 23 forward curved blades, a nominal flow rate at around 352 m 3 /h and a specific speed n s = 1.9. This type of squirrel cage fans is often used as blowers for automobile applications or for small industrial equipment. The flow in this kind of fans happens to be quite complex and with unsteady features. Unsteady flow separation at the machine inlet or at the impeller blades and a variety of flow induced vibrations is found for most of the operation conditions. In this context, the deterministic decomposition becomes an essential tool to analyze the main flow structures, like the evaluation of the non-uniformities induced by the volute tongue over the blade-to-blade distributions within the impeller. As a consequence, fluctuation levels in the blade loadings, derived from deterministic non-uniformities, can be provided in the relative frame of reference. The practical applications of the conclusions do imply a progress in the knowledge of the working parameters for machines that affect in a direct way to the passengers comfort.

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Section: -Machine Descriptionmentioning

confidence: 99%

Section: -Introductionmentioning

confidence: 99%

Numerical methodology for the assessment of relative and absolute deterministic flow structures in the analysis of impeller–tongue interactions for centrifugal fans

et al. 2013

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“…Compared to the radial blade, the forward-skewed blade is proved to be more efficient, total pressure radio, stable operating range and less aerodynamic noise. Velarde-Suarez 19 presented an experimental study on the reduction of aerodynamic tonal noise of forward-skewed centrifugal fan by modifying the volute tongue geometry. Grilliat 20 performed an experimental study on a single airfoil at a low Mach number to investigate the tip leakage flow and the associated broadband noise in the anechoic wind tunnel.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation and experimental research on the aerodynamic performance of large marine axial flow fan with a perforated blade

Yang

Wen

et al. 2017

Journal of Low Frequency Noise, Vibration and Active Control

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In this study, some of the optimal parameters for a new-style marine axial flow fan are defined by using numerical simulation and experimental tests with a large marine axial flow fan, based on the analysis of the blade perforation’s influences on its internal flow field and aerodynamic noise characteristics. Test result shows that the noise reduction for the axial flow fan with perforated blade is about 3 dB when the blade perforation diameter D is 10 mm and its deflection angle α is 45°. The results of the study show that there is an inhibitory effect on the discrete noise of axial flow fan with perforated blade on the tip area, and its total noise level emerged as the fluctuated distribution characteristics with the increase in the perforation diameter D and reduced along with the increase in the deflection of perforation angle α, at the same time varied as a linear characteristics, which can be reasonably explained by the acoustic interference theory. The results of the study have also further confirmed that the improvement of the flow of axial flow fan with perforated blade helps to reduce the pressure pulsation amplitude caused by the turbulence of the blade surface boundary layer, thereby suppressing the back-flow and vortex from the pressure surface to the suction surface efficiently. It is indicated that the improved vortex shedding phenomenon at the blade trailing edge after perforation on the area of blade tip is the main reason for the aerodynamic noise reduction of axial flow fan.

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“…A purified orbit diagram (POD) technique is used to complement previous efforts of the research group, according to different previous publications. 9,10,11,[20][21][22][23] It can be considered in the frame of previous works by the same working team, see, for instance, Velarde-Sua´rez et al, 9 Ballesteros-Tajadura et al, 11,20 Gonza´lez et al 21 and Delgado et al 22,23 Experimental set-up and measurements For the particular application, a squirrel cage fan unit to be studied is built with a pair of twin impellers' unit, arranged as shown in Figure 1 (left sketch). The two impellers are placed on both sides of the electrical motor and supported by the two sides of the shaft in cantilever, from its central position.…”

Section: Introductionmentioning

confidence: 99%

Purified orbit diagram and numerical study for a failure analysis of a Sirocco fan

González

Delgado

Oro

et al. 2017

Advances in Mechanical Engineering

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Sirocco fan units are very common and widespread solution for air conditioning used in public transportation applications (buses or trains). The users' comfort and tranquillity are main concerns in the automotive industry. Inside such turbomachines, the flow structure always becomes highly three dimensional and unsteady, compromising the referred comfort, and sets the focus on the working flow variables. A mathematically exact solution for that flow, which would provide any required information on pressure or forces, is out of scope at the current engineering design processes. Nevertheless, some flow features and mechanical data are needed to progress in the frame of a modern industrial environment, which each time more strongly, besides the different design procedures, involves maintenance protocols. The correctness of a given maintenance protocol relies on its feasibility to handle a set of machine working parameters or variables, including a number of them as wide as possible. Doing so, a set of non-dangerous ranges for them can be established. Such ranges are often defined promoting a series of failures similar to real ones, when the machine is in its usable lifetime. In what refers to the flow analysis, a reasonably good tool has been developed using a computational fluid dynamics technique and, from the experiments, a better understanding of the fan operating conditions is accomplished. For a Sirocco fan unit and to establish proper working ranges for maintenance purposes, a series of failures have been experimentally and numerically tested. Initially, real data from industry have been required and a list of main failures was made. It included impeller or rotor unbalance, impeller channel obstruction and blocked inlet. The first two failures are studied using a purified orbit diagram technique and the last one is numerically analysed. All four working conditions are studied for at least three different flow rates and, therefore, a deeper insight into the fan working parameters and options is made feasible. In the frame of the maintenance protocol, a full set of ranges for the considered failures have been obtained.

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Reduction of the Aerodynamic Tonal Noise of a Forward-Curved Centrifugal Fan by Modification of the Volute Tongue Geometry

Cited by 11 publications

References 0 publications

Numerical methodology for the assessment of relative and absolute deterministic flow structures in the analysis of impeller–tongue interactions for centrifugal fans

Numerical methodology for the assessment of relative and absolute deterministic flow structures in the analysis of impeller–tongue interactions for centrifugal fans

Numerical simulation and experimental research on the aerodynamic performance of large marine axial flow fan with a perforated blade

Purified orbit diagram and numerical study for a failure analysis of a Sirocco fan

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