Numerical Simulation Of The Flow Field For Air-conditioner Outdoor Set And The Noise Prediction Of Its Axial Fan

With the advance of standard of living and the renovate of consume concept, the technical indexes, like noise, flow rate, and efficiency for axial flow fans which are installed in the air-conditioner outdoor set, receive great attention in the design. In this paper, the inner flow field of the outdoor set is simulated by commercial CFD software-Fluent to study the influence on its flow field and acoustic field caused by the various geometric parameters. The aeroacoustic noise is forecasted by using Lighthill acoustic analogy method, and the reliability of this method to forecast the aeroacoustic noise of the axial fan is discussed also. The particular works contain two aspects:First, based on the assembly drawing and performance target of the air-conditioner outdoor set which is supplied by the manufacturer, a reasonable CFD computational model of the outdoor set with its components has been built. This provides a theoretical foundation and the basis of numerical simulation for optimizing the structure of the outdoor set later. On this basis, the improvement of its duct system has been carried out.Second, the aeroacoustic noise of the axial fan is simulated by the commercial CFD software-Fluent. The results are analyzed to provide some theoretical basis for the differences of the noise characteristic obtained from experiment between the two fans. At the same time, the validity of the numerical simulation has been verified by comparing the CFD results.The whole paper is divided into five chapters. In Chapter 1 (INTRODUCTION), the progress at home and abroad of the numerical simulation and its experimental study of axial flow fan is discussed. In Chapter 2 (STUDY OF THE TIP VORTEX IN AXIAL FLOW FAN FOR AIR-CONDITIONER OUTDOOR SET),we simulated the three-dimensional flow characteristics of the tip vortex of axial flow fans used in air-conditioner outdoor set including in the model all the set components (motor, exchanger…). The numerical model solves the three-dimensional Reynolds-Averaged N-S equations together with the RNGκ-εturbulent model and the SIMPLE algorithm. The spectral distribution and the inner flow results of the fan when taking the blade surface as the noise source are studied In Chapter 3 ( AERODYNAMIC NOISE PREDICTION OF THE AXIAL FAN IN AIR CONDITIONER OUTDOOR SET)to provide reference for designing low-noise axial fan. The experimental results provide the checking basis for numerical simulation in Chapter 4(NOISE MEASUREMENT EXPRIMENTAL STUDY).The flow channel structure of the air-conditioner duct system is optimized by experiment and CFD method in Chapter 5(IMPROVEMENT OF THE DUCT SYSTEM FOR AIR-CONDITIONER OUTDOOR SET).