Numerical Investigation of Natural Gas Pipeline Physical Explosions with a Compressibility-Factor-Based Non-Ideal Initial State Correction

Abstract

Long-distance high-pressure natural gas pipelines underpin low-carbon energy supply, and rupture of an in-service segment radiates an overpressure wave whose impact radius governs safety-distance determination. Current assessment relies on the TNT-equivalence method, whose point-source geometry, instantaneous energy deposition, and ideal-gas treatment contradict the cylindrical source, finite-rate efflux, and non-ideal initial state of an actual rupture, leaving safety distances systematically biased. An Arbitrary Lagrangian-Eulerian (ALE) fluid-structure interaction model coupling crack propagation with gas release is constructed in LS-DYNA, in which the initial gas state is corrected using the compressibility factor Z, representing a non-ideal initial-state correction rather than a fully real-gas equation of state. Benchmarked against the P4 full-scale X90 burst, the ALE framework reproduces the measured peak overpressure within 4.6% at 10m and 29.0% at 50m, whereas the TNT simulation overshoots the 10m peak by 24.5% and underpredicts the 50m peak by 69.4%. The Z-correction alone contributes a 9.7% peak uplift at 10m, providing a physically consistent basis for refining pipeline safety-distance provisions.