The Geometry Design And Structure Investigation Of Centrifugal Compressor Blade

The centrifugal compressor is a kind of rotating impeller machinery. Accelerated by the rotating impeller, the gas was improved in kinetic energy and pressure. The diffuser will slow down the gas and furtherly increase it's pressure, after which the proper gas will be obtained. With the advantage of large flow, compact structure and high efficiency, the centrifugal compressor was widely used in every field in national production. As the most important part in centrifugal compressor, the impeller blade should be comprehensively investigated due to his great influence on the compressor performance and efficient working range.The Bezier curve is adopted to design the profile of the meridional plane; Based on the relative profile length, the proper blade angle distribution types are chosen for the hub profile and shroud profile, followed with the establishment of the models of three different blades. Result from CFD reveals that when blade angle distribution type of hub profile is set to front loading and the shroud profile is set to middle loading, the compressor can get the best performance and uniform blade pressure.After the discussion of the influence of blade thickness to the compressor performance, the stress distribution and the deformation of blade are investigated using the Fluid-Structure Interaction (FSI) method. During the analysis process, the blade pressure^ the centrifugal force and the synergistic effect of the above two loads are considered independently. Result from FSI shows that, compared to the blade pressure, the centrifugal force has much more influence on the stress distribution and the deformation; the two loads has the same direction contributing to the maximum total deformation, however the two loads may not enlarge the maximum equivalent stress; the danger point locates on the leading edge, near the hub of the blade, with the maximum equivalent stress showing up at the pressure side at the leading edge near the hub; the maximum total deformation locates on the leading edge near shroud of blade.It is well known that the tip clearance has influence on the compressor performance. In this paper, six impeller models with different tip clearance height are built, followed by the detailed investigation of the influence of tip clearance on the compressor performance and flow inside the compressor. A series of conclusions are obtained:the increase of tip clearance height will result to the decrease of isentropic efficiency and total pressure ratio; the existence of tip clearance affects the distribution of the static pressure of blade at the top area, and will result to the uniform distribution of blade load; when the tip clearance height goes up, the mass of tip clearance leakage flow will increase with a linear trend; the existence of tip clearance affects the main flow in the compressor channel, the affected area locates at the downstream of the flow near the shroud of the impeller; the tip clearance leakage flow has influence on the flow of the vaneless diffuser, the influenced flow starts at the inlet and end at the exit.The results and conclusions obtained in this paper provide a reference for the design and optimization of the semi-open radial centrifugal compressor.