The Spiral Design Of Outlet Volute For Centrifugal Compressor

Centrifugal compressor has the advantages of high compact structure, light weight, easy operation, simple maintenance and high speed, can be directly drived by machine, easy to be controlled automatically. Therefore it has been widely used in several areas, such as in the areas of air separation, coal chemical industry, and petrochemical industry. In all the fields, it plays an extremely key role. At present, people mainly focused on the improvement and optimization of the main rotating element. For a long time, people mainly focused on the improvement and optimization of the main rotating element, the impeller of the centrifugal compressor, to improve the performance of the compressor, while the stationary components, such as the volute was ignored.However, with the development of the research work, the potential to improve the impeller’s performance is gradually exhausting. Therefore, people start to be keen on the researching of the stationary components, such as the diffuser and the volute, in order to improve their energy conservation potential and the overall performance of the unit. In the traditional design of the volute, a large portion of the small cross section would be cut off near the throat of the volute so that the small cross section domain is connected to the discharging pipe directly. This may create an inner loop flow inside the volute, and cause some additional flow loss.A new design of the volute was proposed based on SBW’s volute in this paper, each section of the volute was added with an axial displacement, so that the centerline of each section has been in the form of a helix shape line, and the small section and discharging pipe had no longer intersect with each other. Therefore, the inner flow losses had been avoided and the efficiency of the compressor had been increased. The research method has been verificated by the experiment. The performance of new design product is improved, meanwhile, the manufacture and operating cost is reduced. It is a big significance to enhance the corporate competitive force.In order to ensure the accuracy of the calculation results, a complete model with a whole stage and the inner volute for gas extraction was established. The model is consists of impeller, diffuser, bend, middle gas extraction, backflow and exhaust volute. The commercial computational fluid dynamics software FINE-TURBO was used for the numerical simulation of the flow inside the physic model. The detailed performance parameters as well as the detailed flow parameters distribution were obtained and analyzed. The main research conclusions are listed as follows:different design parameters were adjusted based on the simulation and analysis results, and a final design was obtained.Simulation results show that an increment of1.15%of the efficiency can be achieved by this new design method, and the aerodynamic parameters distribution of the full flow field, including extraction structure, are obtaine. The impact of the different spiral every cross section along the axial offset on the efficiency is analysed. The efficiency of the volute tongue deflector arrangement is limited, and brings about certain difficulty to processing and manufacturing, so this structure design is give up based on the requirement of engineering and economic consideration. The design method proposed in this thesis can be applied to all the inner volute structure design.