Study on pressure balance and clearance flow characteristics of composite-grooved piston–copper pair

Combining different nonsmooth surface structures on the friction pair can form a synergy effect of pressure and increase both the pressure balance and clearance flow characteristics. In view of the above findings, a composite-grooved structure, which combines with a helical groove and an annular groove, is designed in this paper and applied in a piston–copper pair. Compared with the existing related research, this paper has more scientific methods and multifaceted systematic. The numerical simulation method is applied to analyze the flow characteristics of six composite-grooved pistons from the aspects of pressure distribution, tilting torque and clearance leakage, the pressure balance and clearance flow. Results show that different groove patterns and different groove designs have different effects on the effectiveness of piston–copper pairs. Through comprehensive analysis, the specific influence of different groove patterns and groove designs is given, and the design instructions for improving the pressure balance and clearance flow characteristics of the piston–copper pair are obtained. Therefore, the result and methodology presented in this paper are expected to be used to design new-type piston.