管道输送CO₂作为碳捕集、利用与封存（carbon capture, utilization, and storage, CCUS）技术的中间纽带，对CCUS系统的运行起到至关重要的作用。而泄漏是CO₂管输过程中的主要风险，其中泄漏速率是评估管道泄漏事故的关键指标。由于泄漏过程涉及压力和物性的剧烈变化，仿真方法往往难以收敛。同时经典小孔泄漏对于CO₂管道泄漏的计算精度无法满足实际需求。为解决这一问题，提出了一种基于等熵膨胀过程和壅塞效应的数学模型，考虑缩脉效应对泄漏的影响，对泄漏口流通面积进行修正。该模型可用于CO₂管道泄漏口的温度、压力和泄漏速率的准确计算，其预测结果与泄漏实验数据吻合良好，表现出较高的计算精度和稳定性，显著优于经典小孔泄漏模型。该模型可为泄漏远场扩散的研究提供泄漏源强数据，进而为CO₂管输安全工程方面的决策提供参考。

The pipeline transportation of CO₂ plays a crucial role in carbon capture, utilization, and storage (CCUS) systems as an intermediate link. Leakage is the primary risk in CO₂ pipeline transportation process, with the leakage rate being a key indicator for assessing pipeline leakage incidents. Due to the significant variations in pressure and thermophysical properties during the leakage process, simulation methods often face convergence difficulties. Moreover, the classical small-orifice leakage model fails to meet the accuracy requirements for CO₂ pipeline leakage calculations. To address this issue, a mathematical model based on isentropic expansion and choked flow effects was proposed. The effect of vena contracta on leakage was considered, and the flow area at the leakage orifice was modified. This model allows for accurate calculation of the temperature, pressure, and leakage rate at the CO₂ pipeline leak, with the predicted results aligning well with experimental leakage data, demonstrating high computational accuracy and stability, significantly outperforming classical small-orifice leakage models. This model can provide leakage source strength data for research on far-field leakage dispersion, thereby offering a valuable reference for decision-making in CO₂ pipeline transportation safety engineering.