Design Method Of Single-Plate Blade By Load Distribution Control And Internal-Flow Analysis On Centrifugal Fan

Controlling loading distribution method is a kind of design method of blade shape line by adjusting the loading distribution on the blade surface. Because of the difference of the relative velocity between the pressure side and suction side called blade loading, loading adjusting could be carried out by way of changing the relative velocity contrast or other physical quantity that can express the blade loading.Single-plate blade and hollow-airfoil blade are two kinds of blade widely used on centrifugal fan. Both compared with each other, hollow-airfoil blade has better performance but accordingly high cost of manufacture. In addition, the hollow-airfoil blade is easily fretted in particle-rich environment that can lead the blade rotating to imbalance, which has a strong negative impact on the operation of fan. Compared with hollow-airfoil blade, single-plate blade has obvious advantages on cost of manufacture and operation stability, although aero performance of that is a little lower.The thesis focuses on the blade design based on 4-72 centrifugal fan. First, CFD simulation and analysis is carried out on the hollow-airfoil blade impeller in full working range with business CFD software. Basic character of flow field and performance curves of this impeller can be got. Flow losses is mainly concentrated on the near-shroud section called blade-end loss. Second, under the given working condition, different single-plate centrifugal blades are designed with several kinds of loading distribution by loading distribution method. In order to choose the best loading distribution, CFD simulation and analysis on the impellers above are adopted. Simulation result shows that impeller designed by forward loading distribution method has better efficiency and pressure rise. By comparison of the CFD result of new single-plate blade and hollow-airfoil blade, such conclusions can be got: without changing the shape of hub and shroud line and the number of blades, single-plate blade designed by the theory of loading distribution can get as high efficiency and pressure ratio as that of hollow airfoil blade. At the meantime, single-plate centrifugal impeller could prevent blade from being fretted in particle-rich environment that can lead the blade rotating to imbalance.