Development of High-Efficiency Half-Ducted Propeller Fan for Packaged Air Conditioners

2014 ◽  
Author(s):  
Taku Iwase ◽  
Tetsushi Kishitani
Keyword(s):  
Noise Level ◽  
High Efficiency ◽  
Static Pressure ◽  
Suction Side ◽  
Design Tool ◽  
Optimization Techniques ◽  
Aerodynamic Noise ◽  
Air Conditioner ◽  
Fan Noise ◽  
Ducted Propeller

We developed a high-efficiency half-ducted propeller fan to reduce the electric power consumption of the outdoor unit of a packaged air conditioner by using a design tool combining computational fluid dynamics (CFD) with multi-objective optimization techniques based on a genetic algorithm (GA). The baseline fan was a half-ducted propeller fan with three blades of a currently available product. Blade shape was defined using 16 design variables including inlet and outlet blade angles, setting angles, blade length, sweep angles, dihedral angles, and so on. An in-house program was used to automatically generate the grids for CFD calculation. The objective functions were static pressure efficiency and fan noise level for optimization. The fan noise was calculated with an aerodynamic noise prediction model that used the relative inlet and outlet velocities of the fan blades from the CFD results. We found there was a trade-off relationship between the static pressure efficiency and the fan noise. We then selected the optimized fan that had the same noise level as the baseline fan but with an improved static pressure efficiency. The blade tip of the optimized fan was curled toward the suction side direction. Finally, we confirmed through experiments that the static pressure efficiency of the optimized fan was increased by 1.6% compared to the baseline fan.

Development of High Efficiency Propeller Fan for Heat-Pump Unit Using CFD and Numerical Optimization

2011 ◽  
Author(s):  
Hironobu Yamakawa ◽  
Taku Iwase ◽  
Shigehisa Funabashi ◽  
Kouichi Sakamoto ◽  
Yutaka Enokizu ◽  
...  
Keyword(s):  
Numerical Optimization ◽  
Flow Model ◽  
High Efficiency ◽  
Optimization Techniques ◽  
Aerodynamic Noise ◽  
Navier Stokes ◽  
Objective Functions ◽  
Fan Noise ◽  
Heat Pump Unit ◽  
Computational Fluid Dynamics Cfd

We developed a high-efficiency propeller fan to reduce electric power consumption of the fan motor for outdoor heatpump units, and we developed a designing tool combining computational fluid dynamics (CFD) with multi-objective optimization techniques based on the genetic algorithm (GA). In CFD, a numerical model is calculated using commercial software based on steady state, Reynolds-averaged Navier-Stokes (RANS) and k-ε turbulent flow model. The objective functions are fan efficiency and fan noise for optimization. Fan efficiency is calculated directly from the CFD results, and fan noise is calculated using an aerodynamic noise prediction model using the relative inlet and outlet velocities of the fan blades from the CFD results. We fabricated a high-efficiency propeller fan characterized with curled trailing edge tips from Pareto optimal solutions. The experimental results from the performance of the fan showed the developed fan was more efficient than conventional fan.

Calculation of Aerodynamic Noise for Centrifugal Fan of Air-Conditioner

2013 ◽  
Author(s):  
Taku Iwase ◽  
Hideshi Obara ◽  
Hiroyasu Yoneyama ◽  
Yoshinobu Yamade ◽  
Chisachi Kato
Keyword(s):  
Sound Pressure ◽  
Static Pressure ◽  
Pressure Fluctuations ◽  
Coarse Grid ◽  
Aerodynamic Noise ◽  
Absolute Velocity ◽  
Centrifugal Fan ◽  
Air Conditioner ◽  
Simulation Code ◽  
Fine Grid

Flow fields in a centrifugal fan for an indoor unit of an air-conditioner were calculated with finite element method-based large eddy simulation (LES) with the aim of predicting fan performance and aerodynamic noise in this study. The numerical simulation code employed throughout the LES was called FrontFlow/blue (FFB). We compared 10M grid [coarse grid] and 60M grid [fine grid] calculation results for investigation of influence of grid resolution. In the fine grid, the number of grid elements in blade-to-blade direction, and of region between the shroud and the bell mouth increased in particular. By calculating with the fine grid, calculated distributions of absolute velocities at blade exit reasonably agreed with experimental results. Because of this, maximum absolute velocity by fine grid near hub decreased as compared to those by coarse grid. Calculated sound pressure level by fine grid was therefore smaller than that by coarse grid, and the overestimation of sound pressure was suppressed by calculating with fine grid. This decrease of the absolute velocity was a first factor for the improvement of calculation accuracy. Moreover, number of captured streaks on the blade, hub, and shroud surfaces by fine grid increased as compared to those by coarse grid. As a result, size of streak by fine grid became smaller than that by coarse grid. Static pressure fluctuations by fine grid on the blade, hub, and shroud surfaces therefore reduced as compared to those by coarse grid. Aerodynamic noise was related to static pressure fluctuations according to Curle’s equation. This reduction of static pressure fluctuations was therefore a second factor for improvement of calculation accuracy.

The Influence of Non-Uniform Impeller on the Cross Flow Fan Noise

2016 ◽  
Vol 693 ◽  
pp. 251-256
Author(s):  
Zhi Qiang Yang ◽  
C.J. Wu
Keyword(s):  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Internal Flow ◽  
Broadband Noise ◽  
Aerodynamic Noise ◽  
Air Conditioner ◽  
Fan Noise ◽  
Power Spectral ◽  
Cross Flow Fan

The aerodynamic noise of a cross flow fan with uneven blade spacing in room air-conditioner was simulated by computational aerodynamic acoustics (CAA) method. It is detailed to analyze the vorticity distribution of the flow field and the power spectral density of measured points’ pressure fluctuations, and the results demonstrate the non-uniform impeller used in this paper can significantly improve internal flow characteristics. Thus the broadband noise got reduced.

Numerical and Experimental Investigation of Flow Behaviour and Aerodynamic Noise in Axial Flow Fan of Air-Conditioner

2011 ◽  
Author(s):  
Xifeng Zhao ◽  
Jinju Sun ◽  
Zhi Zhang
Keyword(s):  
Hybrid Method ◽  
Performance Test ◽  
Noise Analysis ◽  
Aerodynamic Performance ◽  
Aerodynamic Noise ◽  
Air Conditioner ◽  
Acoustic Analogy ◽  
Fan Noise ◽  
Trailing Edge ◽  
Impeller Blade

To improve aerodynamic performance and reduce noise for a split air conditioner outdoor unit fan, a hybrid method is developed, which combines the Computational Fluid Dynamics (CFD) flow simulation with Computational Aero Acoustics (CAA) noise analysis, where Large Eddy Simulation (LES) model and Ffowcs Williams-Hawkings (FW-H) acoustic analogy model are solved respectively for the unsteady flow characteristics and far field noise solutions. Experimental tests are conducted respectively for fan aerodynamic performance and acoustic behavior, with the aerodynamic performance test rig and semi-anechoic room. Numerical results demonstrates that the main dipole sound sources are located mainly on the blade trailing edge and tip surface, and shroud and casing inner surface, such a distribution is caused by fluctuations in instantaneous pressure associated with rotor-stator interaction. The casing dipole sources contribute largely to the total noise of the fan, and are the main causes for fan noise. It is demonstrated both numerically and experimentally that modifications of impeller blade geometry are effective to reduce the fan noise. Two redesign schemes, the concaved-trailing edge and flanging outer-edge blades, are used, but the latter is more effective in reducing the fan noise as well as shaft power simultaneously. The predicted SPL agrees well with the measured results at the fundamental frequency of the highest intensity, and the hybrid method used in the present study is justified.

Quantitative Evaluation of Flow-Induced Fan Casing Structural Vibration and Noise Radiation of Air-Conditioner Outdoor Unit

2014 ◽  
Author(s):  
Xifeng Zhao ◽  
Jinju Sun ◽  
Renheng Gao ◽  
Zhi Zhang ◽  
Weifei Xue
Keyword(s):  
Quantitative Evaluation ◽  
Noise Level ◽  
Sound Radiation ◽  
Numerical Approach ◽  
Structural Vibration ◽  
Aerodynamic Noise ◽  
Response Analysis ◽  
Air Conditioner ◽  
Radiation Boundary Conditions ◽  
Noise Radiation

Noise level of AC (Air-Conditioner) outdoor unit fan system has always been receiving much concern. It involves both aerodynamic noise and vibroacoustic noise. But most previous studies have been focused on aeroacoustics, and less attention is paid to the latter. The objective of present study is to identify the influential factors of vibroacoustic noise and quantify its contribution to the overall noise level of the fan system. A numerical approach has been developed for predicting the flow-induced fan casing vibration and noise radiation. A fluid-solid-sound unidirectional coupling technique is used to transfer the unsteady loading to the structure, and the results arising from structural vibration analysis are used as sound radiation boundary conditions. Unsteady fan flow is solved by Large Eddy Simulation (LES) method. Then, the fluid force produced by the fluctuating pressure component acting on the inner casing surfaces is obtained, and it is used as external excitation in the Finite Element Analysis (FEA) model of the casing structure. Further, harmonic response analysis is conducted and the obtained results are used to calculate sound radiation through Indirect Boundary Element Method (IBEM), while the displacement amplitude obtained in structural analysis is used as boundary condition. Experimental tests are conducted respectively on fan aerodynamic and aeroacoustic performance, and casing vibration. The numerical approach is partially validated by the experimental data. The validated models are used to predict the vibroacoustic noise, based on which, a quantitative evaluation of its contribution to overall sound level is conducted.

Investigation of the Flow and Noise Distribution on a Blower via Integration of Simulation and Experiments

2017 ◽  
Vol 34 (2) ◽  
pp. 151-158 ◽  
Author(s):  
Y. D. Kuan ◽  
J. M. Huang ◽  
J. H. Wong ◽  
C. Y. Chen ◽  
S. M. Lee ◽  
...  
Keyword(s):  
Flow Field ◽  
Noise Level ◽  
High Efficiency ◽  
Characteristic Curve ◽  
Aerodynamic Noise ◽  
Noise Distribution ◽  
Carbon Reduction ◽  
The Difference ◽  
And Performance ◽  
Experimental Values

AbstractAs the consciousness of energy saving and carbon reduction and comfortable environment is paid increasing attention to, the common objective of various countries with decreasing energy is to develop and popularize high efficiency and low running noise blowers. This study uses CFD to calculate the flow field and performance of a blower and compare with the experimental measurement. The characteristic curve of blower shows that the simulated and experimental values are close to each other, the difference between the values is only 0.4%. This analysis result proofs the CFD package is a highly reliable tool for the future blower design improvement. In addition, this study discusses the noise distribution of blower flow field, the periodic pressure output value calculated by CFD is used in the sound source input of sound pressure field, so as to simulate and analyze the aerodynamic noise reading of the flow field around the blower. The result shows that the simulated value of flow field around the fan has as high as 80.5 dB(A) ∼ 81.5 dB(A) noise level and is agree with measurement (82 dB(A)). The noise level is low but has a sharp noise. According to the numerical results, designer of the blower modify the tongue geometry and remove the sharp noise.

scholarly journals Low-pressure reversible axial fan with straight profile blades and relatively high efficiency

2012 ◽  
Vol 16 (suppl. 2) ◽  
pp. 593-603 ◽  
Author(s):  
Zivan Spasic ◽  
Sasa Milanovic ◽  
Vanja Sustersic ◽  
Boban Nikolic
Keyword(s):  
Numerical Simulations ◽  
High Efficiency ◽  
Suction Side ◽  
Standard Test ◽  
Maximum Efficiency ◽  
Specific Work ◽  
Blade Profile ◽  
Operating Characteristics ◽  
Axial Fan ◽  
Increase Energy Efficiency

The paper presents the design and operating characteristics of a model of reversible axial fan with only one impeller, whose reversibility is achieved by changing the direction of rotation. The fan is designed for the purpose of providing alternating air circulation in wood dryers in order to reduce the consumption of electricity for the fan and increase energy efficiency of the entire dryer. To satisfy the reversibility of flow, the shape of the blade profile is symmetrical along the longitudinal and transversal axes of the profile. The fan is designed with equal specific work of all elementary stages, using the method of lift forces. The impeller blades have straight mean line profiles. The shape of the blade profile was adopted after the numerical simulations were carried out and high efficiency was achieved. Based on the calculation and conducted numerical simulations, a physical model of the fan was created and tested on a standard test rig, with air loading at the suction side of the fan. The operating characteristics are shown for different blade angles. The obtained maximum efficiency was around 0.65, which represents a rather high value for axial fans with straight profile blades.

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