Gas explosion overpressure and impact airflow velocity attenuation model

In order to reduce the great threat of gas explosion to coal mine operators and coal safety mining, the law of explosion overpressure and impact airflow velocity attenuation with the propagation distance of different volumes of gas-air mixed gas in roadway was deeply studied. Firstly, based on dimensional analysis, factors affecting the single-direction propagation attenuation of gas explosion overpressure in roadway were comprehensively considered, such as mixed gas energy, gas accumulation amount, measuring point distance and related parameters of roadway, and a dimensionless formula of single-direction propagation attenuation of gas explosion overpressure in roadway was obtained. Based on the regression analysis of the test data of gas explosion overpressure in large-size roadway, the mathematical model of unidirectional overpressure propagation attenuation in roadway was established, and the mathematical model of bidirectional overpressure propagation attenuation in roadway was established according to the law of energy similarity. According to the analysis process of influencing factors of single-direction propagation attenuation of gas explosion overpressure in roadway, a dimensionless formula of single-direction propagation attenuation of impact airflow velocity in roadway was obtained. Through regression analysis of test data of gas explosion impact airflow velocity in large-size roadway, a mathematical model of single-direction propagation attenuation of impact airflow velocity in roadway was established. According to the law of energy similarity, the mathematical model of the bidirectional propagation attenuation of the impact airflow velocity in the roadway was established. Secondly, according to the establishment process of the mathematical model of the unidirectional and bidirectional propagation attenuation of overpressure and impact airflow velocity in the roadway, the impact airflow velocity was included as one of the influencing factors in the consideration of the unidirectional propagation attenuation of gas explosion overpressure in the roadway in addition to the mixed gas energy, gas accumulation amount, measuring point distance and relevant parameters of the roadway. Based on the energy similarity law, the overpressure-airflow velocity relation of overpressure propagation attenuation in roadway was established. According to the establishment process of the overpressure-airflow velocity relation of the single and bidirectional propagation attenuation of gas explosion overpressure in roadway, the airflow velocity relation of the single and bidirectional propagation attenuation of the impact airflow velocity in roadway was established. Finally, the attenuation model and the mathematical relationship between overpressure and impact airflow velocity were verified. The results show that the energy of gas mixture, gas accumulation amount, the distance of measuring point, the hydraulic diameter and the cross-sectional area of roadway are the main factors affecting the attenuation of overpressure and impact airflow velocity. Both overpressure and impact airflow velocity are positively correlated with the amount of mixed gas accumulation. The greater the initial overpressure and impact airflow velocity, the faster the attenuation. The relative errors between the theoretical value and the test value of the attenuation model and the relative errors between the theoretical value and the test value of the relation are controlled at about 10%, and the overall consistency of the data is high, which verifies the reliability of the model and the mathematical relation, and can describe the law of gas explosion propagation more simply and intuitively, and realize the rapid calculation of overpressure and impact airflow velocity.