Study On The Aerodynamic Optimization And Structure Improved Design Of Semi-Open Impeller

As a general machinery products,centrifugal compressor occupies an important status in the national economy, and its operating performance has a great influence on the use of energy. With the rapid development of economic society, the demand of energy is rising, therefore, improving the centrifugal compressor performance and enhancing its efficiency, making full use of existing energy sources, clearly has very important practical and long-term significance.As the core component of centrifugal compressor, the performanc of impeller determines the efficiency of the whole machine. Therefore, how to improve the impeller aerodynamic performance and improve the impeller rotor dynamic characteristics is a focus in the study of this article. The paper performs optimization analysis on semi-open impeller, concrete research have been focused on two aspects of blade type and structure of the impeller back plate.In this paper, using the impeller machinery sector dedicated CFD simulation analysis software NUMECA to simulate the inner flow field of semi-open impeller, To find the problems existing in the impeller, the paper uses the existing international famous NREC mechanical design software for the optimization design of impeller. With the new design by software, concrete structure and assembly approach unchanged, the polytropic efficiency increased by 2.05%.With new design method be taken, although the efficiency of the impeller is improved, relative to the high performance and high efficiency of impeller, the rise is not very ideal, the impeller efficiency is low, and do not accord with the requirement of high performance impeller design. Based on the purpose of further enhancement of the efficiency of the impeller, this paper puts forward a new design scheme of the structure of impeller back plate. Using finite element analysis software ANSYS, considering the impeller itself operation of the centrifugal force and the flow field aerodynamic load factors such as joint action, which is under the condition of considering fluid-structure coupling interaction, the finite element analysis was carried out on the impeller, considering factors such as impeller stress and strain, getting the optimal design scheme. The optimal design of impeller back plate obviously improve the rotor dynamic characteristic of the impeller, the impeller run vibration amplitude reduced half. Vibration amplitude and original impeller impeller blade tip clearance design is 0.6 mm, was relatively large. Through optimizing design, we can more precisely control the blade tip clearance, making its value within the range of control in a more ideal. Making use of NUMECA to do the CFD simulation of final design of the impeller, finding 2.966% of the impeller polytropic efficiency promoted, eventually impeller polytropic-efficiency reached 90.689%,fully meeting the requirements of practical engineering.This paper performs contrastive analysis for three kinds of impeller type load distribution on the blade surface static pressure, finding that eventually new impeller blade surface loading distribution be more uniform and reasonable. At the end, the paper also simulates and analyses the off-design condition, finding the new impeller still can have high efficiency under the condition of variable flow, indicating that impeller runs stably and has good performance of off-design working condition.