Numerical study on the damping characteristics of a shock absorber valve utilizing different velocities through CFD analysis

Abstract

Shock absorbers or hydraulic dampers are power dissipating devices. The fluid flow inside the damper is governed by predefined passages. The damping effect is accomplished by the resistance of oil to flow through the restrictions. The impact of the viscosity and the velocity of the oil determines the fluid flow behaviour and hence, the resulting damping effect. The piston inside the damper has various orifices or piston valves that cause different flow losses. These losses are observed during the extension and compression strokes of the damper. In the compression and extension strokes, rebound and compression pressures are developed at the damper orifice. In this work, Computational Fluid Dynamics (CFD) analysis is carried out on a rear side two-wheeler automobile mono tube damper to investigate the variation of the damping properties using viscous oils. Averaged Navier-Stokes equations are solved by the SIMPLE method and the RNG k-ε is used to model turbulence. The piston contains eight orifices which separate the rebound and compression chambers of the damper. The numerical analysis used four values of velocity; 0.8, 1, 1.2, and 1.5 m/s. The viscous fluid model was SVI2.5, having viscosity value of 0.009 Pa.s. The damping coefficient values for rebound and compression sides were obtained based on their pressure values showed in the CFD contour plots. It was noticed that the increasing trend of damping coefficient is linearly for two velocity's intervals; (0.8-1) m/s and (1.2-1.5) m/s, and nonlinearly for velocity interval of (1-1.2) m/s.