| The centrifugal fan, as an indispensable turbo-machinery to industry and daily life, are used widely. In the certain project application, in order to make use of shaft work of prime mover, simplify the process and save space, air-induced supercharge should be integrated to the equipment system. However, the traditional volute centrifugal fan cannot meet the requirement because it has large size in radial direction and because it has the tangential outlet Therefore, this paper put forward and design a set of embedded booster fan, which is also called guide vane booster fan based on its structural characteristics.First, in order to reduce the size of the equipment, this paper designs and optimizes vane diffuser. Then, the author designs parameterized outlet of the guide vane to change the direction of air outflow. Last, for the simplified three-dimensional model, the numerical analysis and distributions of the inner flow field are discussed. Meanwhile, the effect of both structural parameters and operating parameters on each element and whole structure are investigated. The following conclusions can be drawn:(1) Under the design requirements of small flow, small radial size, large pressure ratio and fane with changing direction, it is a good attempt to match vane wheel with vane diffuser and guide vane in outlet. Under standard conditions, total pressure efficiency of the whole machine can reach about 78% and static pressure efficiency can reach about 77% by matching them reasonably. The mass flow rate within economical operational zone is in the range of 0.15kg/s-0.32kg/s, and the stable region above 0.17kg/s, according with the theory condition.(2) The transition between dynamic pressure and static pressure can be divided into two steps:the conversion ratio inside the vane diffuser is 62%, accounting for 52.7% of total kinetic energy. Majority energy realizes the first conversion inside the vane diffuser; the conversion ratio inside outlet guide vane is 85%, accounting for 12.75% of total kinetic energy. Minority energy realizes the second conversion inside the outlet guide vane. The transition of the whole machine between dynamic pressure and static pressure is 65.45%, reaching the requirement of energy conversion.(3) Compared to the effects of outlet guide vane on the performance of the whole machine, the largest effect results from the vane diffuser. The parameters of the vane diffuser with the most influence on the performance of the whole machine are given as following: inner and outer diameter of the diffuser, width of the diffuser and warp angle of the vane. With the increasing of each parameter, the trends of pressure rise, efficiency and conversion are firstly increases and then decreases, appearing an optimal value in the middle. Envelope angle in arc segment of outlet guide vane have the greatest influence on the performance of the whole machine. On a small scale, pressure rise, efficiency and conversion ratio have increasing trend. On the contrary, the tangential velocity has a decreasing trend. Therefore, designing the vane diffuser reasonably plays a key role in guaranteeing the excellent performance of the whole machine.(4) The conversion of the guide vane is not influenced by changing flux rate basically. However, the conversion of the vane diffuser is influenced greatly. The energy conversion of the vane diffuser is decreased with increasing the flux rate. The change is slow in the range of small flux rate and drastic in the range of big flux rate. Analyzing the results shows that the performance of booster and whole model decreases when the flow rate increases to 1.4 times of design flow rate. |
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