Design And Optimization Of Centrifugal Compressor Impellers By Distribution Of Blade Loading

Centrifugal Compressor occupies an important position in various departments of the national economy, and as a core component of centrifugal compressor, the performance of impeller affects centrifugal compressor even the whole industrial process, so the design and optimization method of centrifugal impeller have been concerned by researchers.The design method of centrifugal impeller is mainly divided into two categories, direct design and inverse design. The direct design method changes the blade profile by controlling parameters of geometry directly, and estimates the performance on blade by CFD numerical simulation which relies on the design experience to a large extent while in the inverse method the required flow distribution is specified and the corresponding blade geometry is computed which avoids the drawback of direct method. So the problems that how to achieve an efficient blade through reasonable blade loading distribution come forth.The 3D inverse design method is used to design a medium flow coefficient shrouded centrifugal impeller. Different blade loading distributions are applied to the shroud and the hub in order to investigate effects of different blade loading distributions on aerodynamic performance, geometry parameters and flow field of centrifugal impellers. Results show that higher design efficiency can be obtained with front-loading on the shroud, but the surge margin is narrow. While for the shroud with after-loading, higher efficiency at small flow rates are achieved, but coupling with a faster efficiency drop at large flow rates. The middle-loading shroud has a wide working range. Blade loading distributions on the hub also have great influence on aerodynamic performance of the impeller. Compared with the front and middle loading distributions, the after-loading distribution on the hub can obtain higher efficiency and wider working range. Where the internal flow phenomena such as backflow, secondary flow and friction loss were analysed in this article and summarized conclusions in the design process of centrifugal impellers by different blade loading distributions.At last, two typical centrifugal impellers, a large flow coefficient and a medium-small coefficient impeller, were designed and optimized according to the obtained conclusions. The design point efficiency of the large flow coefficient impeller is 96.5% coupling with widely operating range, and the stage efficiency of medium-small flow coefficient was increased by 1.3%. The resulting conclusions provide guidance for design and optimization of centrifugal impellers.