Acoustic characteristic simulation analysis and noise reduction design of dual-tube shock absorber compensation valves

Noise generated by shock absorbers during vehicle operation significantly affects ride comfort. However, the single-phase flow-acoustic coupling mechanisms within the internal valve system remain insufficiently explored. To address this, this study establishes a systematic framework integrating diagnostic experiments, computational aeroacoustics (CAA), and physical validation. Bench tests first utilized a mechanical retaining ring to isolate the compensation valve as the root source of abnormal noise during the rebound stroke. Subsequently, a single-phase CAA model, combining the SST k-ω turbulence model with the Lighthill acoustic analogy, was developed. Results indicate that high-frequency noise is fundamentally driven by localized velocity surges, shear layer instabilities, and separation-induced dipole sources at the micro-throttling gaps. A parametric sensitivity analysis revealed that the bottom valve’s constant-flow orifice radius and the throttle hole dimensions are highly sensitive parameters governing fluid dynamics and acoustic radiation. Notably, oil viscosity exhibits a distinct hydrodynamic threshold above 0.0104 Pa·s, where excessive viscosity exacerbates hydrodynamic blockage and massive flow separation, increasing noise intensity. Finally, a joint multi-parameter collaborative optimization was implemented. Physical bench tests confirmed that the optimized valve structure synergistically relieved local jetting velocities, achieving an absolute external radiated noise reduction of 7.1 dB while successfully maintaining the required damping force. This study provides a rigorous theoretical and engineering foundation for the low-noise design of automotive shock absorbers.