Fig. 5 Vibration model of dynamic vibration absorber attached to diesel engine
Specification of engine and generator for this study is shown on Table 5 and X-moment at generator synchronized speed with 100% load is as Table 6. For theoretical investigation assuming 6th resonance occurs at synchronized speed 103.4 rpm, four cases of mass ratio 1/15, 1/30, 1/60, 1/120 are considered. Absolute damping of foundation, hysteresis damping at absorber inner spring and X-moment In each load are conformed to actual condition for detail calculation and calculated amplitudes of dynamic vibration absorber and engine are shown on Fig. 6 and Fig. 7. As the diagram it is true that 6th X-mode resonance is more widely separated as bigger dynamic vibration absorber is applied, however it should be designed considering engine operating range, X-mode natural frequency of engine and space for fitting it in engine.
For this project, it is finally decided and made as μ= 1/60 size which are fitted at engine fore and after cylinder frame. If filled with oil with high viscosity, dynamic vibration absorber may be used for tuning damper. To check this effectiveness, vibration amplitude is simulated with optimum damping whose results show it can be reduced to one fifth of the previous non oil filled dynamic vibration absorber.
Table 5 Specification of the 9K80MC-S power stationary engine.
Fig. 6 6th order trans velocity amplitude of dynamic absorber moving part
