Prediction of Flow-Induced Noise in Automotive HVAC Systems Using a Combined CFD/CA Approach

Ayar, Ayhan; Ambs, Raymond; Capellmann, Christoph; Schillemeit, Balthasar; Matthes, Marcus

doi:10.4271/2005-01-0509

Cited by 12 publications

(3 citation statements)

References 7 publications

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“…In general, CFD simulation, particularly large eddy simulation (LES) is often used to predict the noise level of a blower unit. 9,10 However, it needs high mesh resolution and requires huge simulation cost to predict turbulence-induced noise directly. Thus, it is preferable to predict the sound pressure level (SPL) of the blower unit at a lower cost.…”

Section: Validation Of An Indirect Noise Prediction Methodsmentioning

confidence: 99%

Multi-objective design optimization of a high efficiency and low noise blower unit of a car air-conditioner

Kamada

Shimoyama

Sato

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part D:

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Car air-conditioners consist of a blower unit and a heater unit. A blower unit sends wind to a heater unit, and a heater unit adjusts the temperature inside the vehicle. Blower units of car air-conditioners are required to be smaller, lighter, noiseless, and power-saving. However, it is difficult and expensive to predict the noise directly by computational fluid dynamics simulation. Hereupon, this study employs an indirect noise prediction method based on a noise prediction theory to evaluate noise for blower units inexpensively. This method is investigated through a comparison with actual sound pressure level measurement. Then, using this method, this study moves to design optimization of a blower unit of car air-conditioners. The optimization aims to improve total pressure efficiency and sound pressure level from the current design that has been employed for a real commercial vehicle. This study employs a genetic algorithm to explore global optima in a two-objective problem. The present genetic algorithm is assisted by the Kriging surrogate model to reduce computational cost required for evaluating objective functions. The optimization results indicate that the optimized blower unit involves a multi-blade fan with the high chord-pitch ratio to decrease the loss of total pressure efficiency, which is often induced by the flow separation on the blade and the swirling flow on the meridional plane. In addition, the sound pressure level of blower unit can be reduced by decreasing the local flow velocity on the meridian plane due to a blockage factor. A blower unit, which has a scroll with a large tongue angle, shows high total pressure efficiency because the increase in eddy loss is suppressed at the tongue. They suggest the importance of the matching of multi-blade fan and scroll to achieve the good overall performance of a blower unit.

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Section: Validation Of An Indirect Noise Prediction Methodsmentioning

confidence: 99%

Multi-objective design optimization of a high efficiency and low noise blower unit of a car air-conditioner

Kamada

Shimoyama

Sato

et al. 2019

Proceedings of the Institution of Mechanical Engineers, Part D:

View full text Add to dashboard Cite

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“…In researches conducted by Santos (1995), Khondge et al (2005), Ayar et al (2005), Mohamud and Johnson (2006), Croaker et al (2011), Junger (2019, the Proudman's Formula Model (Proudman 1952) and the Boundary Layer Noise Source Model (Curle 1955) are used and presented as a low-cost computational tool to identify the main noise sources, which represents an attractive option to quickly and inexpensively evaluate the acoustic performance, especially in the design phase, as it allows optimizing the parameters related to the main sources of noise.…”

Section: Aeroacoustics Behavior -Aeroacoustics Sourcesmentioning

confidence: 99%

Free and Non-Free Vortex Design for Axial Fans with Circumferential Sweep through CFD Techniques

2022

JAFM

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The sound generated by axial flow fans has become increasingly important in several industrial areas. These devices represent considerable noise sources that must be considered from the design stage. The scope of this research work is to present an axial fan design methodology based on the theory of the wing lift and to compare the aerodynamic and aeroacoustics behavior with the free vortex and the non-free vortex conditions. The effect of forward circumferential sweep on the rotor blades is analyzed in both conditions, which consists of a displacement in the tangential direction in the direction of rotor rotation. A cubic polynomial function is proposed for the construction of the blade geometry with circumferential sweep. It defines the center line of the blade and it is taken at 50% of the leading edge of each blade profile. The methodology for analyzing aeroacoustics behavior in fans is based on the integration of Computational Aeroacoustics and Computational Fluid Dynamics in order to analyze aerodynamic behavior, sound power level and sound pressure level at the preliminary design stage. It was verified that although both rotors present a similar aerodynamic behavior (the NFV rotor has a slightly lower performance), according to the analysis of local sound sources, the NFV rotor presents a slight decrease in the sound sources. It was also verified that the NFV rotor presents 2.2 dB less in sound pressure level than the FV rotor.

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“…Since the flow in the centrifugal fan is typically three-dimensional turbulent, it is appropriate to solve the unsteady Reynolds averaged Navier-Stokes equations (URANS) economically without loss of resolving the main characteristics of flow fields such as mean pressure fluctuations. Ayer et al [1], Reese et al [20] and Tournour et al [21] pointed out that by solving unsteady RANS together with the turbulence model it can provide adequate unsteady flow information to predict the tonal noise of fans, but Large Eddy Simulation (LES) should be employed when predicting broadband noise. For the three dimensional calculations, structured hexahedral cells were used to define the inlet zone, the impeller and the volute, with a total of 1,597,262 and 1,958,378 cells for the origin fan and skewed cutoff fan, respectively.…”

Section: Simulations Of Internal Flowsmentioning

confidence: 99%

Study of the Tonal Casing Noise of a Centrifugal Fan at the Blade Passing Frequency. Part I. Aeroacoustics

Xiao

2010

Journal of Low Frequency Noise, Vibration and Active Control

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This paper is concerned with the simulation of the unsteady turbulent flow and the aerodynamic tonal noise due to pressure fluctuations on the casing wall. Three-dimensional numerical simulations of the complete unsteady flow on the whole impeller-volute configuration were carried out using computational fluid dynamics (CFD) techniques. Pressure fluctuations on the casing wall were obtained, and the blade passing frequency (BPF) component was extracted to be modeled as the dipole source term of the wave equation. In a companion paper, the pressure fluctuations served as the external excitation to the casing vibration. Multi-domain direct boundary element method (BEM) was used to simulate the noise radiation with two domains representing the interior and exterior fields of the volute respectively, in order to take account of the sound scattering effect by the volute casing. Results showed that the dipole on the volute tongue surface was the most dominant noise source of the fan. Slopingedge volute tongue was introduced to reduce BPF noise radiation through phase cancellation between the dipole sources over the volute tongue.Key words: centrifugal fan; casing; blade passing frequency; acoustic dipole source INTRODUCTIONCentrifugal fans, pumps and compressors are widely employed for industrial and civilian use. Their noise has been studied extensively, and is customarily classified into aerodynamic noise and structural noise. The noise spectrum of a centrifugal fan is characterized by broadband noise with pronounced discrete frequency tones. The broadband component arises from random fluctuations in pressure over a wide range of frequencies, and is associated with turbulent flow in the inlet stream, in the boundary layer, and the wake behind the blade. The prevailing discrete frequency tones are caused by the interaction between the mean air flow leaving the impeller and the fan casing. Among them, the BPF component is usually the most noticeable. This paper focuses on the numerical study of the BPF casing aerodynamic noise of a centrifugal fan through CFD and computational aeroacoutics (CAA). The BPF component of the noise spectra about this centrifugal overwhelmingly dominated other frequencies. Its companion paper studies the BPF casing vibration-induced noise. CAA is concerned with the prediction of the aerodynamic sound source and the transmission of the generated sound. The approaches used to solve the aeroacoustic problems can be generally classified into two broad categories: direct computation and indirect, or hybrid, computation. The direct approach computes the sound together with its fluid dynamic source field by solving the compressible flow equations. In a hybrid approach, the computation of flow is decoupled from the computation of sound, which can be done in a post-processing step based on an aeroacoustic theory [24]. Although recent advances in CFD and in computer technology have made the

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Prediction of Flow-Induced Noise in Automotive HVAC Systems Using a Combined CFD/CA Approach

Cited by 12 publications

References 7 publications

Multi-objective design optimization of a high efficiency and low noise blower unit of a car air-conditioner

Multi-objective design optimization of a high efficiency and low noise blower unit of a car air-conditioner

Free and Non-Free Vortex Design for Axial Fans with Circumferential Sweep through CFD Techniques

Study of the Tonal Casing Noise of a Centrifugal Fan at the Blade Passing Frequency. Part I. Aeroacoustics

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