Internal flow field and operational efficiency evaluation model of hydraulic cylinder considering inlet pressure and clearance impacts

This study addresses the critical issue of the coupling effect between inlet pressure and radial clearance on hydraulic cylinder operational efficiency, proposing a comprehensive evaluation method combining numerical simulation using dynamic mesh technology and empirical equations. By establishing a piston-cylinder clearance flow field model, the dynamic correlation mechanisms of oil film pressure gradient, leakage characteristics, and energy dissipation under different operating conditions are systematically revealed. The results indicate that under high inlet pressure (2 MPa), an optimal threshold of 0.75 mm for radial clearance is identified, where efficiency improves by 5%. However, once the threshold is exceeded, leakage increases sharply, leading to a significant decline in efficiency. At low pressure (1 MPa), leakage dominates energy consumption, with minimal impact from changes in clearance on energy efficiency. Furthermore, the oil film pressure and velocity gradients jointly regulate system response. Narrow clearances result in a faster response but higher energy consumption, whereas moderate clearances balance leakage and shear losses, enhancing system stability. This study provides theoretical support for hydraulic system energy efficiency optimization and clearance design.