# Gas explosion characteristics and spray control mechanism in underground square

## TL;DR

This paper studies how gas explosions behave in underground pipelines and how spray systems can control them, finding that optimal spray pressure reduces explosion overpressure.

## Contribution

The study identifies optimal spray pressure (0.6 MPa) for suppressing gas explosion overpressure in underground square pipelines.

## Key findings

- Gas explosion overpressure has three stages: gentle, rising, and decay, with rapid growth and slow decline trends.
- Spray pressure influences explosion suppression in a promotion–inhibition–promotion pattern across different pressure ranges.
- At 0.6 MPa spray pressure, peak overpressure and propagation rates are minimized, achieving the best suppression effect.

## Abstract

The spray system mechanism during a gas explosion in an underground square pipeline is complex. In this paper, the underground square of Fuxin City is selected as the research object. FLACS numerical simulation software is used to analyze the spatial and temporal distribution characteristics of a gas explosion in an underground square pipeline with an unopened spray system using combustion and combustion rate models. Different spray pressures were compared and analyzed to determine the optimal spray control pressure, and the spray system mechanism was clarified. The results revealed that the gas explosion overpressure is divided into the overpressure gentle, overpressure rising, and overpressure decay stages, corresponding to a trend of rapid growth and slow decline. The influence of spray pressure on the gas explosion exhibits a promotion–inhibition–promotion trend, corresponding to 0–0.2 MPa, 0.2–0.6 MPa, and 0.6–1.6 Mpa, respectively. The peak overpressure and overpressure propagation rates are the lowest at 0.6 MPa, and the explosion suppression effect is the most pronounced. The spray system mechanism varies with the explosion overpressure stages. Generally, the time to peak value, that is, the peak time, the overall duration of the explosion, and the duration of the explosion stage decrease, whereas the peak explosion overpressure decreases.