Abstract: In view of the problem of insufficient powder spraying distance of heavy-duty powder fire trucks, it is proposed to use secondary pressurization to improve the spraying distance of heavy-duty powder, and the influence of the position of secondary pressurization, the number of pressurized ports and the pressure on the spraying effect of powder in fire trucks is analyzed through theoretical analysis, numerical simulation and experimental study. Research indicates that, compared with directly raising the pressure of the main driving gas source, the secondary pressurization through the transportation pipeline can more effectively reduce the pressure loss of gas-solid two-phase flow to enhance the exit velocity and range of the powder. The position of the pressurized port has a greater impact on the powder injection range, and the powder injection effect of secondary pressurization in the middle of the boom is better than that of pressurization at both ends of the boom. The powder injection distance increases with the increase of pressurization pressure, and the secondary pressurization at 0.15 MPa in the middle of the boom can increase the maximum exit velocity and effective powder coverage by 61.8% and 28.4%, respectively, showing the best injection effect.

Key words: elevating fire truck, pneumatic conveying, secondary pressurization, spraying distance, gas-solid two-phase flow