为了满足涡旋压缩机对综合性能优良型线的需求，本文提出了一种结合渐变截面与变截面优势的三段变径基圆渐开线（Three-segment Variable-Radius Involute，T-VRI）涡旋型线模型。首先，基于微分几何理论，建立了基于曲率半径函数的T-VRI的统一数学模型。接着，详细推导了吸气腔和排气腔的容积计算公式，并提出了容积比、面积利用系数及泄漏线长度等几何评价指标。最后，利用有限元仿真软件Pumplinx对T-VRI型线的变截面涡旋压缩机进行了计算流体动力学（CFD）数值模拟。研究结果表明：在相同安装尺寸下，相较于传统圆渐开线等截面型线，T-VRI型线的内容积比提升了18.37%，面积利用系数提升了9.19%，从而提高了容积效率与材料利用率；相比具有相同容积比的变径基圆渐开线（Variable-Radius Involute ， VRI）渐变截面型线，泄漏线长度减少了19.47%。此外，相邻高压腔及对称工作腔的压差分别降低了22.16%和11.55%，有利于涡旋压缩机的更平稳运行，该研究为高性能变截面涡旋型线的设计提供了理论支持与方法依据。

To address the demand for scroll compressors with enhanced overall performance, this paper introduces a Three-segment Variable-Radius Involute (T-VRI) scroll profile, which combines the advantages of gradually varying and variable cross-sections into a single design. First, a unified mathematical model for the T-VRI is developed using differential geometry, based on the curvature radius function. Following this, detailed formulas for calculating the volumes of the suction and discharge chambers are derived, and key geometric evaluation metrics such as volume ratio, area utilization coefficient, and leakage line length are proposed. Finally, Computational Fluid Dynamics (CFD) simulations of the flow field within the T-VRI scroll compressor are performed using the Pumplinx software. The study's findings indicate that, under identical installation dimensions, the T-VRI profile increases the internal volume ratio by 18.37% and the area utilization coefficient by 9.19% compared to traditional circular involute equal-section profiles, thereby enhancing both volumetric efficiency and material utilization. Additionally, compared to the VariableRadius Involute (VRI) profile with a gradually varying cross-section and the same volume ratio, the T-VRI profile reduces leakage line length by 19.47%. Furthermore, the pressure differentials in adjacent high-pressure chambers and symmetrical working chambers are reduced by 22.16% and 11.55%, respectively, contributing to more stable compressor operation. This research provides valuable theoretical support and methodological guidance for the design of high-performance variable cross-section scroll profiles.