Limit And Shakedown Analysis Of Centrifugal Compressor Impeller

Impeller is an important rotating component of the centrifugal compressor.Its limit and shakedown analyses are of great engineering significance to determine its safety performance and to improve enterprise's economic benefit.However,the shakedown analysis of complex three-dimensional structures is a difficult problem.In this paper,the linear matching method(LMM)based on the upper bound shakedown theorem is applied to the complex three-dimensional structure,and the limit and shakedown analyses of the enclosed and unshrouded impellers are carried out to broaden the engineering applicability of the method.The main research contents include the following aspects:(1)Based on the finite element analysis software ABAQUS platform,the linear matching method for three-dimensional structures is studied and a general program is compiled.The limit and shakedown domains of a holed plate subjected to biaxial loading as well as a cantilever beam under the combined action of axial tension and bending moment are calculated.The validity of the algorithm is verified by comparative analyses.The limit and shakedown loads of some numerical examples with different element types are compared to investigate the influence of element types.The results show that the linear matching method is suitable for the three-dimensional solid element.The results of calculation with the same element type and different grid densities are also compared to analyze the mesh convergence of the algorithm.(2)The limit and shakedown speeds of the enclosed and unshrouded impellers under the action of centrifugal force are obtained through the limit and shakedown analysis.The calculated results by using the linear matching method are compared with these by using the elastic-plastic incremental method,the step-by-step method and the double elastic limit load method to demonstrate the accuracy and the applicability of the linear matching method.By comparing the calculation time of different solution methods,the efficiency of the linear matching algorithm is verified.The limit and shakedown domains of the enclosed and unshrouded impellers under the combined action of centrifugal force and internal pressure on axle hole are obtained.(3)Yield area ratio is an important parameter to measure the safety state of the impeller.The yield area ratios of the enclosed and unshrouded impellers are calculated and the change rule of them with rotating speed is analyzed,which reveals the relationship between yield area ratio and shakedown speed.