• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.26 no.4
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• pp.383-390
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• 2016

In this paper, experiment and dynamics simulations were carried out to identify and reduce the out-of-plane vibration that occurs in a centrifugal fan of an air conditioner installed to a wall. In a wall-installed air conditioner, large space between a case and heat exchanger is often required for the fan to avoid the collision with the case and exchanger. This large space hinders the slim design of the air conditioner even if air conditioner market demands a slim air conditioner. In the present study, in order to determine the cause of the vibration in the centrifugal fan, the out-of-plane vibration and the physical properties were investigated, and the dynamic characteristics of the centrifugal fan were obtained by experiments. Based on these experiments, a dynamic simulation model was established to determine the cause of the out-of-plane vibration of the centrifugal fan. It was found that the main factor of out-of-plane vibration in the centrifugal fan is the axial misalignment between the centrifugal fan and the motor shaft.

• International Journal of Fluid Machinery and Systems
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• v.5 no.4
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• pp.168-173
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• 2012

This paper presents a numerical investigation on the aerodynamic performance according to the application of splitter blades in an impeller of a centrifugal fan used for a refuse collection system. Numerical analysis of a centrifugal fan was carried out by solving three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model. A validation of numerical results was conducted by comparison with experimental data for the pressure and efficiency. From analyses of the internal flow field of the reference fan, the losses by the reverse-flows were observed in the region of the blade passage. In order to reduce these losses and enhance fan performance, two splitter blades were applied evenly between the main blades, and centrifugal impellers having the different numbers of the main blades were tested with their application. Throughout the numerical analyses of the centrifugal fan with splitter blades, it was found that the reverse-flow regions in the blade passage can be reduced by controlling the main blade numbers with splitter blades. The application of splitter blades in a centrifugal fan leads to significant improvement in the overall fan performance.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.529-535
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• 2001

A centrifugal fan design code was developed and packaged together with iDesignFan／sup TM／ as new models. This code generate centrifugal forward curved and backward curved bladed impeller optimally. It also predicts the aerodynamic performance and the overall sound pressure level of the rotating fan by assuming steady blade loading. The overall sound pressure level is used as an input parameter from the third loop of the designing process to acquire the most silent fan for the given aerodynamic performance parameters. With this kind of inverse design concept used in the code, the period of designing a fan is significantly shortened. A centrifugal fan design code, developed in this study and included in iDesignFan／sup TM／, predicts the aerodynamic performance such as design flow rate and static pressure. The aerodynamic performance in the design and off-design conditions is calculated by using the mean line analysis. For the steady loading calculation, the lift force distribution in a blade is used.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.381-385
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• 2009

This paper describes performance characteristics of a centrifugal fan having a different volute casing. The centrifugal fan has a backward blade type, and is used in a refuse collecting system. The flow characteristics inside the components are analyzed by three-dimensional Navier-Stokes analysis, and also compared to the results by experiments. Distributions of pressure and efficiency obtained by numerical simulation has a good agreement with the experimental results. Throughout the numerical simulation of the centrifugal fan, a fan efficiency is increased by decreasing local losses in the blade passage. It is found that the fan efficiency is enhanced by decreasing the distance between the shroud of a impeller and casing. Detailed flow analysis is also analyzed and discussed using the results obtained by numerical simulation.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.11-16
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• 2001

It is not easy to apply a small-sized centrifugal fan to the duct used for the thermal management of home electronic appliances due to complex design parameters of its blades and scroll. The main objective of this study was to develop the systematic process to design an optimal centrifugal fan based on the 3-dimensional configuration of blades obtained from the conceptual design program self-developed with the given design constraints such as the flow rate, the total pressure loss, the size of fan, and the number of rotation. The design process to find an optimal centrifugal fan for refrigerator was technologically linked in many ways. The complex grid generation system of the fan model included scroll was adopted for the numerical simulation. The FVM CFD code, FLUENT, was used to investigate the three dimensional flow pattern at the coordinate system of rotating frame and to check the optimal performance of the fan. By using this design process, a selected centrifugal fan was designed, numerically simulated, manufactured and experimentally tested in the wind tunnel. The performance curve of fan manufactured by NC process was compared with numerically obtained characteristic curve. The developed design method was proved into being excellent because these two curves were well matched.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.48-53
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• 2001

A centrifugal fan design code was developed and included in $DasignFan^{TM}$. This program generates forward -curved and backward-curved bladed centrifugal fan data. With the inverse design concept used in the code, the period of designing a fm, which has given aerodynamic performance with minimal acoustic noise, is significantly shortened.. A centrifugal fan design code, developed in this study and included in $DasignFan^{TM}$, predicts the aerodynamic performance by using mean-line analysis and various loss models. In the period of design a lift force distribution between pressure side and suction side of blade is calculated. And then it is used to calculate steady loading noise from the impeller.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.5
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• pp.589-596
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• 2006

This study aims to propose a new model axial flow fan which attachs centrifugal blades, and to investigate the effect of centrifugal blades on the performance improvement of new model axial flow fan. A numerical simulation has been conducted using STAR-CD commercial code to solve the three dimensional incompressible Navier-Stokes equation for high Reynolds number $k-{\epsilon}$ turbulent model. Numerical simulation is carried out to investigate the detail phenomenon in the flow field and performance characteristics of new model and normal model fan. Calculation results are compared with normal model's results to investigate which centrifugal blades effect on velocity profile and pressure distribution at various flow field positions. and calculation results show that new model fan can improve the performance of total pressure.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.12
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• pp.1138-1145
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• 2011

The internal broadband noise of a centrifugal fan in a household refrigerator is predicted using hybrid CAA techniques based on stochastic turbulent synthetic model. First, the unsteady flow field around the centrifugal fan is predicted using computational fluid dynamics(CFD) method. Then, the turbulent flow field is synthesized by applying the stochastic turbulent synthetic technique to the predicted flow field. The aerodynamic noise sources of the centrifugal fan are modeled on a basis of the synthesized turbulent field. Finally, the internal broadband noise of the centrifugal fan is predicted using the boundary element method(BEM) and the modeled sources. The predicted noise spectrum is compared with the experimental data. It is found that the predicted result closely follows the experimental data. The proposed method can be used as an effective tool for designing low-noise fans without expensive computational cost required generally for the LES and DNS simulations to resolve the turbulence flow field responsible for the broadband noise.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.627-632
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• 2011

The internal broadband noise of a centrifugal fan in a household refrigerator is predicted by using hybrid CAA technique based on stochastic turbulent synthetic model. First, the unsteady flow field around the centrifugal fan is predicted using Computational Fluid Dynamics (CFD) method. Then, the turbulent flow field is synthesized by applying the stochastic turbulent synthetic technique to the predicted flow field. The aerodynamic noise sources of the centrifugal fan are modeled on a basis of the synthesized turbulent field. Finally, the broadband noise of the centrifugal fan is predicted using Boundary Element Method (BEM) and the modeled sources. The predicted result is compared with the experimental data. It is found that the predicted result closely follows the experimental data. The proposed method can be used as an effective tool for designing low-noise fans without expensive computational cost required generally for the LES and DNS simulations to resolve the turbulence flow field responsible for the broadband noise.

• Journal of KSNVE
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• v.9 no.5
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• pp.955-965
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• 1999

Centrifugal fans are widely used and the noise generated by the these machines causes one of the most serious problems. In general, the centrifugal fan noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged form the impeller and the cutoff in the casing. However, only a few researches have been carried out on predicting the noise because of the difficulty in obtaining detailed information about the flow field and casing effects on noise radiation. The objective of this study is to understand the generation mechanism of sound and to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan. We assume that the impeller rotates with a constant angular velocity and the flow field of the impeller is incompressible and inviscid. So, a discrete vortex method (DVM) is used to model the centrifugal by the unsteady Bernoulli equation. Lowson's method is used to predict the acoustic source. A centrifugal impeller and wedge introduced by Weidemann are used in the numerical calculation and the results are compared with the experimental data. Reasonable results are obtained not only for the peak frequencies but also for the amplitudes of the tonal sound.