Abstract:
Abstract: The distribution of flow field, efficiency and spraying swath of an air-blast sprayer were influenced by its structure and its shape of the duct outlet. In this paper, an additional expansion swath duct was subjoined to the original circular duct in order to make the same air-blast sprayer have different spray characteristics. Aiming at the high duct efficiency, three different types of wide-swath air-blast sprayer's segment of expanding duct structure were optimized via numerical calculation and analysis of the internal flow field by using the RNG k-ε model. The simulating results indicated that the wind flowed in the duct was divide into three stages. The air flow was turbulent near the fan area. Inside the cylindrical duct and contraction duct, the air flow was not only layered but also turbulent. Moreover, in the expanding duct, the air flow was turbulent and the wind speed distributed renewed. Furthermore, the areas where air flow velocity change suddenly in type I and type III ducts were larger than that of type II duct. In the expanding duct, the turbulent area were also larger in type I and type III ducts, and that leaded this two types duct efficiency was more less than that of type II duct. The air flow total pressure at inlet and outlet, the air flow average speed and the duct efficiency were simulated. The optimized structure of expansion swath duct was obtained and the testing prototype was manufactured based on the numerical calculation results. The wind speed at the outlet and the swath of wide-swath air-blast sprayer were tested and measured via prototype test. The test results showed that the error between measuring and simulating of the flow field was within -1.49% to 1.91%. The relationship between spraying swath and blast distance of wide-swath air-blast sprayer appears to be quadratic polynomial. The widest spraying swath measured away from the outlet 4.5m along the duct axial direction was 3.56 m. Compared with the same power air-blast sprayer without segment of expanding duct, the swath of the wide-swath air-blast sprayer was expanded by 55.46%. The errors between numerical calculation and actual measurement were within the engineering tolerated values. The numerical calculation model, boundary conditions, numerical calculation hypothesis, and the methods what selected in this paper can meet the requirement of engineering numerical calculation.