And the change of fans performance is mainly caused by the increase of hydraulic loss inside the impeller due to the concealed motor and the low hydraulic efficiency of the impeller.

• 研究结果表明，电动机长度、外径、头部倾角对风机性能和噪声有较大影响，而内藏电动机引起叶轮内部流动损失增大、叶轮水力效率降低是影响风机性能的主要原因。