Effect of dimensionless vent ratio on the flame-shock wave evolution dynamics of blended LPG/DME gas explosion venting

To reveal the flow field-shock wave-flame coupling evolution law of LPG/DME blended gas explosion venting under different dimensionless vent ratio(K_V), the numerical model for multi-blended gas explosion venting was established and research of blended gas explosion venting at K_V = 0.02–0.21 was carried out based on experimental verification. The results show that, after the vent opens, the turbulence intensity increases, the velocity gradient of the flow field increases, the maximum explosion wind velocity(V_max) of the outfield varies linearly with K_V, and the flame of “mushroom shape” is elongated, and “break flame” occurs under the action of the relative motion of “primary and secondary vortex group”. When K_V＞0.02, the flame propagation velocity increases locally because of the thermal-mass diffusion instability, and with increasing K_V, the average flame propagation velocity decreases from 258.29 m/s to 226.58 m/s. In the process of explosion venting, a typical shock wave fluctuating pressure waveform curve is formed in the outfield. Under the combined action of the infield pressure venting effect and the outfield turbulence intensity, the maximum explosion overpressure in the outfield (P_max) reaches maximum 423.97 kPa at K_V = 0.07. Meanwhile, the larger the K_V, the greater the shock wave velocity due to the lead role of the infield explosion venting shock wave and outfield flame compression shock wave on the shock wave propagation velocity.