The analytical force prediction and dynamic response analysis of the Bristol H25A compressor

The objective of this research is to perform an in-depth study of the force components within the H25A compressor along with a computer simulation program and the dynamic response analysis of the compressor internals using the finite element method.

The model tor force prediction was created based on the assumption that the frame of the shell structure is rigid and the subassemblies within the shell behave as one lumped mass. Springs are the connections between the shell and the subassemblies. Various parameters of the model were entered through the preprocessor of the simulation program which provides a series of data entry forms. The processor part of the program contains several modules for performing different tasks, such as the eigenanalysis, kinematic force computation. displacement/velocity/acceleration prediction, spring-end force calculation and variable-speed motor simulation. The simulation program also features post-processor functions in order to display the results of the analysis in plots, tables or with animation.

Further research was focused on the correlation of the predicted force and orbit with the observations. With a finite element model of the full compressor. the spring-end forces due to the excitation at mass center were obtained from the dynamic response analysis and compared to the force gauge measurements. The excitations included the enforced displacement at the mass center which was regenerated from the accelerometer measurements. and the superposition of the kinematic forces and equivalent valve impact forces at the mass center.