A Study of Design and Analysis of Deswirl Vane in Two-Stage Centrifugal Pressurize Machinery

• Main Authors: Yue-Hann Tsai, 蔡岳翰
• Other Authors: Jeng-Min Huang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/64017177817901808406

碩士 === 國立勤益科技大學 === 冷凍空調系 === 100 === This study numerically investigates the performancs of deswirl vanes in two kinds of centrifugal compression machines. First one is the return system( included vaneless diffusor, return channel, deswirl vane, bend channel) of an low specific speed two-stage high pressure fan. The other one is a two-stage refrigerant compressor with double-row deswirl vanes, and the second row can be used as the IGV of the second-stage impeller. Numeca Fine/Turbois used to calculate the flow field of the R-134a centrifugal compressor while STAR-CD is for the high prssure fan. The turbulent models selected are the Spalart-Allmaras model for compressor and the k-Epsilon High Reynolds Number model for fan. In the high pressure fan, the parameters include inflow angle, length, exit width of vaneless diffuser and the blade number of deswirl vane. This study used the tested impeller to verify the accuracy of numerical calculations, with good consistency. The analytic results showed that the overall pressure loss of impeller and flow return system is effectively reduced when the inflow angle of vaneless diffuseer is 15° and tangential to wheel velocity ratio is 0.46. A vaneless diffuser was required and its length referred to the maximum outer diameter of the volute casing. The performance of a contracted-wall vaneless diffuser was not improved over that of a parallel-wall one. The suggested number of blades in a deswirl vane was 12. The downstream affects the upstream in several areas inside the flow return system, thus, the flow return system must be calculated integrally. In the centrifugal compressor, a two-row deswirl vane which is cutting the single vane at its middle place and staggering 7.5 degres has a better performance than other cutting and staggering. Besides, near surge flow rate, the second row vane of the above double-row deswirl vane rotates 10 degrees resulting only 0.3~0.6% efficiency decrements but residue a tangetial velocity of 15m/s to be the preswirl of second stage impeller. It is suggested using this design as deswirl vane. (Keyword: Deswirl vane, two-stage compression, centrifugal high pressure fan, centrifugal compressor, CFD）