Aerodynamic design and acoustic effect study of key geometric parameters of a sirocco fan

2021 ◽  
Vol 69 (5) ◽  
pp. 431-450
Author(s):  
Chen Wang ◽  
Kai Mai ◽  
Lanhao Fang ◽  
Naitong Liu
Keyword(s):  
Numerical Simulation ◽  
Noise Reduction ◽  
Flow Separation ◽  
Noise Source ◽  
Sound Field ◽  
Source Area ◽  
Broadband Noise ◽  
Design Parameters ◽  
Field Calculation ◽  
Sirocco Fan

A sirocco fan (forward-curved centrifugal fan), including impeller blades and volute, is designed, and the empirical value ranges of several significant design parameters are discussed and summarized fromthe perspective of both aerodynamics and practical structure. Unsteady-flow numerical simulation and radiated sound-field calculation by indirect boundary element method are combined to evaluate its aerodynamic and acoustic performances. Both the discrete noise source from the rotating impeller and broadband noise source from the volute are considered. Obvious flow separation occurs in the flow passage of impeller blades due to large angle of attack, and the tongue region is the major noise source area due to the small impeller-tongue gap. Therefore, parametric studies for blade installation angle and impeller-tongue gap are performed. Analyses of flow- and sound-field indicate that appropriate reduction of blade geometry incidence angle weakens the flow separation, thereby improving both the aerodynamic and acoustic performances, and reasonable increase of the impeller-tongue gap has a remarkable noise reduction effect for the major noise source area near the volute tongue. The optimized sirocco fan meets the requirement of the industrial project, i.e., the far-field A-weighted sound power level lower than 64.0 dB(A), and achieves larger volume flow rate and total pressure rise. The results also imply that fast steady-flow numerical simulation result is indicative of the acoustic performance to some extent if the acoustic evaluation is urgent. Furthermore, optimization of the key structural parameters in the stage of design is preferable in practical engineering, instead of taking follow-up noise reduction measures.

Passive Noise Reduction in an Automotive Compartment

2008 ◽  
Author(s):  
Mariana R. Kruntcheva
Keyword(s):  
Noise Reduction ◽  
Characteristic Impedance ◽  
Three Dimensional ◽  
Sound Field ◽  
Acoustic Resonance ◽  
Design Parameters ◽  
Fe Model ◽  
Luggage Compartment ◽  
Main Compartment ◽  
Complex Picture

Fuel economy, international competition and socioeconomic factors have forced manufacturers to develop lighter automotive vehicles. However, such vehicles are typically more susceptible to noise and vibration problems. The internal sound field in the passenger compartment is affected significantly by the acoustic modal characteristics of the cavity, by the dynamic behaviour of the surrounding structure, and by the nature of the coupling of these two dynamic systems. The purpose of this research is to develop and analyse a new vibroacoustic model containing the main compartment cavity and the luggage compartment cavity. Special attention is placed on the effect of a double walled partition between the main compartment cavity and the luggage compartment. The system is studied using ANSYS finite element (FE) code. The modelling involved shell finite elements for the structure and three-dimensional (3D) acoustic elements for the cavities. The 3D FE modal analysis produced results visualizing the complex picture of acoustic-structure coupling in the lower frequency range (30–200 Hz). It was found that strong coupling between the thin walled structure and the acoustic enclosures exists in the vicinity of any acoustic resonance. The key noise reduction principle examined is the passive application of a characteristic impedance mismatch. Using an FE model, numerical simulations are conducted to study the effect of various design parameters on acoustic transmission. The results show that at least 8 dB reductions in sound pressure level may be achieved with a modest level of vacuum in the double partition between the main cabin and the luggage compartment cavity.

Physics-informed Broadband Noise Source Identification and Prediction of an Ideally Twisted Rotor

2021 ◽  
Author(s):  
Christopher Thurman ◽  
Nikolas S. Zawodny ◽  
Nicole A. Pettingill ◽  
Leonard V. Lopes ◽  
James D. Baeder
Keyword(s):  
Source Identification ◽  
Noise Source ◽  
Broadband Noise ◽  
Noise Source Identification

scholarly journals Noise Reduction Effect of Superhydrophobic Surfaces with Streamwise Strip of Channel Flow

2021 ◽  
Vol 11 (9) ◽  
pp. 3869
Author(s):  
Chen Niu ◽  
Yongwei Liu ◽  
Dejiang Shang ◽  
Chao Zhang
Keyword(s):  
Reynolds Number ◽  
Drag Reduction ◽  
Noise Reduction ◽  
Channel Flow ◽  
Superhydrophobic Surface ◽  
Sound Field ◽  
Flow Noise ◽  
Slip Boundary ◽  
Eddy Simulation ◽  
Reduction Effect

Superhydrophobic surface is a promising technology, but the effect of superhydrophobic surface on flow noise is still unclear. Therefore, we used alternating free-slip and no-slip boundary conditions to study the flow noise of superhydrophobic channel flows with streamwise strips. The numerical calculations of the flow and the sound field have been carried out by the methods of large eddy simulation (LES) and Lighthill analogy, respectively. Under a constant pressure gradient (CPG) condition, the average Reynolds number and the friction Reynolds number are approximately set to 4200 and 180, respectively. The influence on noise of different gas fractions (GF) and strip number in a spanwise period on channel flow have been studied. Our results show that the superhydrophobic surface has noise reduction effect in some cases. Under CPG conditions, the increase in GF increases the bulk velocity and weakens the noise reduction effect. Otherwise, the increase in strip number enhances the lateral energy exchange of the superhydrophobic surface, and results in more transverse vortices and attenuates the noise reduction effect. In our results, the best noise reduction effect is obtained as 10.7 dB under the scenario of the strip number is 4 and GF is 0.5. The best drag reduction effect is 32%, and the result is obtained under the scenario of GF is 0.8 and strip number is 1. In summary, the choice of GF and the number of strips is comprehensively considered to guarantee the performance of drag reduction and noise reduction in this work.

Design of a 0.1~18GHz High-Power Broadband Noise Source

2020 ◽  
Author(s):  
Rikang Zhao ◽  
Tingming Yao ◽  
Xidong Duan ◽  
Guoqing Fan ◽  
Shoumei Cheng ◽  
...  
Keyword(s):  
High Power ◽  
Noise Source ◽  
Broadband Noise

scholarly journals Analysis of the Influence of Different Bionic Structures on the Noise Reduction Performance of the Centrifugal Pump

Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 886
Author(s):  
Cui Dai ◽  
Chao Guo ◽  
Yiping Chen ◽  
Liang Dong ◽  
Houlin Liu
Keyword(s):  
Flow Field ◽  
Noise Reduction ◽  
Centrifugal Pump ◽  
Great Influence ◽  
Frequency Doubling ◽  
Sound Field ◽  
Internal Flow ◽  
Test System ◽  
Centrifugal Pumps ◽  
External Characteristics

The strong noise generated during the operation of the centrifugal pump harms the pump group and people. In order to decrease the noise of the centrifugal pump, a specific speed of 117.3 of the centrifugal pump is chosen as a research object. The bionic modification of centrifugal pump blades is carried out to explore the influence of different bionic structures on the noise reduction performance of centrifugal pumps. The internal flow field and internal sound field of bionic blades are studied by numerical calculation and test methods. The test is carried out on a closed pump test platform which includes external characteristics and a flow noise test system. The effects of two different bionic structures on the external characteristics, acoustic amplitude–frequency characteristics and flow field structure of a centrifugal pump, are analyzed. The results show that the pit structure has little influence on the external characteristic parameters, while the sawtooth structure has a relatively great influence. The noise reduction effect of the pit structure is aimed at the wide-band noise, while the sawtooth structure is aimed at the discrete noise of the blade-passing frequency (BPF) and its frequency doubling. The noise reduction ability of the sawtooth structure is not suitable for high-frequency bands.

Numerical simulation for fan broadband noise prediction

2011 ◽  
Vol 20 (1) ◽  
pp. 58-63 ◽  
Author(s):  
Takaaki Hase ◽  
Nobuhiko Yamasaki ◽  
Tsutomu Ooishi
Keyword(s):  
Numerical Simulation ◽  
Broadband Noise ◽  
Noise Prediction
Sign in / Sign up

Export Citation Format

Share Document