Parametric Optimization of Variable Lead Curves for Screw Rotors in Twin-Screw Air Compressors

Twin-screw air compressors are widely used in industrial applications due to their stability, reliability, and high efficiency. To meet increasing performance demands, optimization of rotor lead curve design has become critical. Multi-stage variable lead designs allow effective control of chamber volume variation, improved gas sealing, and reduced internal leakage. This study investigates the design and performance effects of multi-stage variable lead curves for twin-screw compressor rotors. Under identical rotor profiles, helical section lengths, and wrap angles, multiple variable lead curves are designed and their geometric characteristics compared. The lead curve is divided into suction, compression, and discharge segments, with reference angles derived from constant-lead working conditions to define design parameters. Based on the identified design trends, lead parameters are normalized using constant lead values and wrap angles. A predictive model is developed using a radial basis function approximation integrated with ISIGHT and a uniform experimental design. Global optimization is then performed in Mathematica using a least-squares approach. The optimized designs are validated through geometric analysis and evaluation of volumetric and isentropic efficiencies across different rotational speeds. The results provide useful guidance for rotor lead curve optimization in twin-screw air compressors.