Dynamic analysis.pdfVIP

844 KSME International Journal, Vol. 17 No. 6, pp. 844--853, 2003 Dynamic Analysis of a Reciprocating Compression Mechanism Considering Hydrodynamic Forces T a e - J o n g Kim* School o f Mechanical Engineering and Research Institute o f Mechanical Technology, Pusan National Universit); Pusan 609-735, Korea In this paper, a dynamic analysis of the reciprocating compression mechanism of a small refrigeration compressor is performed. In the problem formulation of the mechanism dynamics, the viscous frictional force between the piston and the cylinder wall is considered in order to determine the coupled dynamic behaviors of the piston and the crankshaft. Simultaneous solu- tions are obtained lbr the equations of motion of the reciprocating mechanism and the time- dependent Reynolds equations for the lubricating film between the piston and the cylinder wall and |br the oil films on the journal bearings. The hydrodynamic forces of the journal bearings are calculated by using a finite bearing model along with the GiJmbel boundary condition. A Newton-Raphson procedure is employed in solving the nonlinear equations for the piston and crankshaft. The developed computer program can be used to calculate the complete trajectories of the piston and the crankshaft as functions of the crank angle under compressor-running conditions. The results explored the effects of the radial clearance of the piston, oil viscosity, and mass and mass moment of inertia of the piston and connecting rod on the stability of the compression mechanism. Key Words: Reciprocating Compressors, Piston Secondary Dynamics, Crankshaft-Journal Bearing System, Hydrodynamic Force, Dynamic Behavior 1. Introduction Compressor manufacturing is characterized by mass production, and therefore a method for pre- dicting the dynamic behaviors of the compression mechanism is required to enhance compressor performance and reliability, and to save time at the design stage. A reciprocating co