Design of intake port parameters for a free-piston engine
BU Xiangqi
XIAO Jin
Abstract：To address the optimization of scavenging performance in a Curtis-type free-piston engine,the horizontal scavenging target point,the inclination angle of the lateral intake ports,and the inclination angle of the intake ports opposite the exhaust port are selected as design variables.An experimental design is constructed using the Box-Behnken response surface methodology,and response surface models are established with charging efficiency,scavenging efficiency,and trapping efficiency as the optimization objectives.On this basis,a desirability function is introduced to achieve multi-objective comprehensive optimization,yielding optimal port geometric parameters that simultaneously account for charging,scavenging,trapping,and short-circuiting losses.Simulation results indicate that when the horizontal scavenging target point is 11.86 mm,the inclination angle of the intake ports opposite the exhaust port is 46.01°,and the inclination angle of the lateral intake ports is 40.37°,the engine achieves the best overall scavenging performance.Under these conditions,the corresponding charging efficiency,scavenging efficiency,trapping efficiency,and delivery ratio are 1.061,0.977,0.331,and 3.205,respectively.The study demonstrates that the integrated response surface-desirability approach provides an effective design framework and parameter selection reference for the multi-objective optimization of scavenging port geometry in free-piston engines.
Keywords：free-piston enginescavenging3D CFD simulationresponse surface methodology(RSM)
Publication Date：2026-02-28
Online Publishing Date：2026-05-22(First online date of this platform, not the publication date of the document)
Pages：10( 11-20 )