Unsteady Fast Random Particle Mesh method for efficient prediction of tonal and broadband noises of a centrifugal fan unit

Heo, Seongmin; Cheong, Cheolung; Kim, Tae-Hoon

doi:10.1063/1.4930979

Cited by 5 publications

(4 citation statements)

References 19 publications

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“…The divergence-free turbulence is coupled into a CAA domain by a sponge-layer technique. For centrifugal fans Heo et al [18] have applied the RPM method to time-periodic flow with cyclostationary turbulence. The synthetic fluctuations are used as sources in an acoustic analogy solved by a boundary element method.…”

Section: Introductionmentioning

confidence: 99%

Impact of cyclostationarity on fan broadband noise prediction

Wohlbrandt

Kissner

Guérin

2018

Journal of Sound and Vibration

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One of the dominant noise sources of modern Ultra High Bypass Ratio (UHBR) engines is the interaction of the rotor wakes with the leading edges of the stator vanes in the fan stage. While the tonal components of this noise generation mechanism are fairly well understood by now, the broadband components are not. This calls to further the understanding of the broadband noise generation in the fan stage. This article introduces the cyclostationary stochastic hybrid (CSH) method, which accommodates in-depth studies of the impact of cyclostationary wake characteristics on the broadband noise in the fan stage. The Random Particle Mesh (RPM) method is used to synthesize a turbulence field in the stator domain using a URANS simulation characterized by time-periodic turbulence and mean flow. The rotor-stator interaction noise is predicted by a two-dimensional CAA computation of the stator cascade. The impact of cyclostationarity is decomposed into various effects investigated separately. This leads to the finding that the periodic turbulent kinetic energy (TKE) and periodic flow have only a negligible effect on the radiated sound power. The impact of the periodic integral length scale (TLS) is, however, substantial. The limits of a stationary representation of the TLS are demonstrated making the CSH method indispensable when background and wake TKE are of comparable level. Good agreement of the CSH method with measurements obtained from the 2015 AIAA Fan Broadband Noise Prediction Workshop are also shown.

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Section: Introductionmentioning

confidence: 99%

Impact of cyclostationarity on fan broadband noise prediction

Wohlbrandt

Kissner

Guérin

2018

Journal of Sound and Vibration

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“…Note that the subsequent detailed flow analysis and the optimization were carried out for the operating point where the P-Q curve and the resistance curve, which is mainly due to the heat changer, meet together. Aerodynamic noise due to fan-driven flow in the out-door unit is also predicted using the FW-H integral equation in Equation (3). The half-spherical shape of the FW-H integral surface was formed in the downstream direction.…”

Section: Validation Of Numerical Modelmentioning

confidence: 99%

“…These studies confirmed that the H-CAA method could be reliably used to predict the BPF noise of the fan unit. By extending these works, Heo et al developed an efficient numerical method for predicting broadband noises as well as tonal noise of a centrifugal fan [3]. The proposed method is based on the Unsteady Fast Random Particle Mesh (U-FRPM) method.…”

Section: Introductionmentioning

confidence: 99%

Optimization of the Orifice Shape of Cooling Fan Units for High Flow Rate and Low-Level Noise in Outdoor Air Conditioning Units

Park¹,

Ryu

Cheong

et al. 2019

Applied Sciences

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Demand for air conditioners is steadily increasing due to global warming and improved living standards. The noise, as well as the performance of air conditioners, are recognized as one of the crucial factors that determine the air conditioners’ values. The performance and noise of the air conditioner are mostly determined by those of its outdoor unit, which in turn depend on those of the cooling fan unit. Therefore, a cooling fan unit of high-performance and low noise is essential for air-conditioner manufacturers and developers. In this paper, the flow performance and flow noise of the entire outdoor unit with an axial cooling fan in a split-type air-conditioner were investigated. First, a virtual fan tester constructed by using about 18 million grids is developed for highly resolved flow simulation. The unsteady Reynolds-Averaged Navier–Stokes equations are numerically solved by using finite-volume computational fluid dynamics techniques. To verify the validity of the numerical analysis, the predicted P–Q curve of the cooling fan in a full outdoor unit is compared with the measured one. There was an excellent agreement between the two curves. The further detailed analysis identifies the coherent vortex structures between the fan blade tip and fan orifice, which adversely affect the flow performance and causes flow noise. Based on this analysis, the optimization of fan orifice was carried out using the response surface method with three geometric parameters: inlet radius, neck length, and outlet angel of the orifice. The optimum layout for the high flow rate is proposed under the understanding that the increased flow rate can be converted to noise reduction. The additional computation using the proposed optimum orifice shows that the flow rate is increased by 4.6% at the operating point. Finally, the engineering sample was manufactured by using the optimum design, and the measured data confirmed that the flow rate were increased by 2.1%, the noise reduction was made by 2.8 dBA, and the power consumption is reduced by 4.0% at the operating rotational speed.

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“…Recently, an attempt to combine the FRPM method with a URANS solution for improved broadband noise predictions called U-FRPM method was developed for a centrifugal fan noise problem [33]. However, the underlining acoustic formulation used in that work remains unclear.…”

Section: Introductionmentioning

confidence: 99%

Aerofoil broadband and tonal noise modelling using stochastic sound sources and incorporated large scale fluctuations

Proskurov

Darbyshire

Karabasov

2017

Journal of Sound and Vibration

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The present work discusses modifications to the stochastic Fast Random Particle Mesh (FRPM) method featuring both tonal and broadband noise sources. The technique relies on the combination of incorporated vortexshedding resolved flow available from Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulation with the fine-scale turbulence FRPM solution generated via the stochastic velocity fluctuations in the context of vortex sound theory. In contrast to the existing literature, our method encompasses a unified treatment for broadband and tonal acoustic noise sources at the source level, thus, accounting for linear source interference as well as possible non-linear source interaction effects. When sound sources are determined, for the sound propagation, Acoustic Perturbation Equations (APE-4) are solved in the timedomain. Results of the method's application for two aerofoil benchmark cases, with both sharp and blunt trailing edges are presented. In each case, the importance of individual linear and non-linear noise sources was investigated. Several new key features related to the unsteady implementation of the method were tested and brought into the equation. Encouraging results have been obtained for benchmark test cases using the new technique which is believed to be potentially applicable to other airframe noise problems where both tonal and broadband parts are important.

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Unsteady Fast Random Particle Mesh method for efficient prediction of tonal and broadband noises of a centrifugal fan unit

Cited by 5 publications

References 19 publications

Impact of cyclostationarity on fan broadband noise prediction

Impact of cyclostationarity on fan broadband noise prediction

Optimization of the Orifice Shape of Cooling Fan Units for High Flow Rate and Low-Level Noise in Outdoor Air Conditioning Units

Aerofoil broadband and tonal noise modelling using stochastic sound sources and incorporated large scale fluctuations

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