| With the improving energy usage efficiency requirement, more attention is being paid to the performance of the indoor unit of an air conditioner, especially the discharge air flux and the noise emission. To optimize the flow channel in the indoor unit and to reduce its noise emission are very necessary for energy saving and better life quality. Based on computational fluid dynamics (CFD) and computational aeroacoustics (CAA), the flow characteristic and the aerodynamic noise of the indoor unit in an air conditioner are studied with the commercial CFD software FLUENT in this dissertation, in order to offer a guideline for the optimization design of the flow channel in air conditioner enterprise and to reduce the test time aiming for flow channel optimization. The main research contents include:1) The flow field and sound field of the flow channel in indoor unit of an air conditioner is simulated by commercial CFD software FLUENT, based on a numerical model of the discharge air flow and the aerodynamic noise of air conditioner's indoor unit. The methods for treating the heat exchanger as porous media, coupling the moving zone and the immobile zone, and setting other numerical parameters are analyzed and discussed.2) Based on the numerical model of the discharge air flow, the influences of the clearance of stabilizer, the rear wall, the angle of outlet on the air flux of indoor unit are analyzed in details.3) Based on the numerical model of aerodynamic noise, the noise source and the aerodynamic noise category are analyzed and summarized, together with the noise frequency characteristics. The results of numerical simulation show that the dipole acoustic sources locating at the wall of stabilizer, the rear wall and the impeller are the main sources, and that the total noise in air conditioner is a combination of discrete and indiscrete noises. The results can be helpful for reducing the design noise in the flow channel of an air conditioner.4) The accuracy of numerical model is validated by the comparison between experimental and numerical results, which supports the universal application feasibility of our model. For the numerical aspect, the independence of the simulation result on the computational zone and the mesh number is analyzed. By comparing the experimental and numerical results, we find that the errors between the simulated and measured results for velocity field and pressure distribution in the flow channel of air conditioner are acceptable.5) Upon parameterizing the cross flow fan of air conditioner, the evolving process and pressure characteristic of eccentric vortex are obtained from the numerical simulation. The relationship between the performance of cross flow fan and the configuration parameter is analyzed, which can be a guideline and reference for the flow channel optimization of cross flow fan.6) Two noise-reducing methods, the frequency modulation based method and the inlet state improving method, are analyzed and suggested to reduce the total noise and to improve the quality of noise in cross flow fan, which can provide some suggestions for reducing the noise emission from the indoor unit of air conditioner.
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