The Implementation and Comparison of Calculation Methods of Natural Torsional Vibrations for Reciprocating Compressors

The problem of torsional vibrations is relevant for reciprocating compressors due to the occurrence of alternating torques that create additional torsional stresses during operation. Such vibrations are particularly dangerous in resonance frequencies when the first natural vibration frequency coincides with the harmonic component of the lower order of forced vibrations. This article analyzes the methods described in the literature for calculating natural torsional frequencies of crankshafts of multirow reciprocating compressors. Recommendations are given on selecting an appropriate calculation method at various design stages. The analytical dependencies that describe three various methods are presented: the iterative method based on moments equation, the method of continued fractions (Tersky’s method) and the matrix method. The stages of calculation are described analytically, and the calculation results are compared. The developed computational software is presented.