Abstract
In order to study the internal flow characteristics and external droplet velocity distribution characteristics of the swirl nozzle, the following methods were used: numerical simulations were used to study the internal flow characteristics of a swirl nozzle and phase Doppler particle velocimetry was used to determine the corresponding external droplet velocity distribution under medium and low pressure conditions. The distributions of pressure and water velocity inside the nozzle were obtained. Meanwhile, the velocities of droplets outside the nozzle in different sections were discussed. The results show that the flow rate in the swirl nozzle increases with the increase in inlet pressure, and the local pressure in the region decreases because of the excessive velocity at the internal outlet section of the swirl nozzle, resulting in cavitation. The experimental results show that under an external flow field, the minimum droplet velocity occurs in the axial direction; starting from the axis, the velocity first increases and then decreases along the radial direction. Swirling motion inside the nozzle and velocity variations in the external flow field occur under medium and low pressure conditions. The relationship between the inlet pressure and the distributions of water droplets’ velocities was established, which provides a reference for the research and development of the swirl nozzle.
Highlights
Water-mist fire extinguishing technology is playing an increasingly important role in the field of modern fire protection
Few studies have been conducted to determine the characteristics of the internal flow in swirl nozzles and the external droplet velocity distribution. erefore, in order to provide more research and corresponding data for reference, the characteristics of the internal flow field and the external droplet velocity distribution of a swirl nozzle are investigated in this study under medium and low pressure conditions; the internal flow profile in the swirl nozzle and the change law of the external droplet velocity are presented
Section (Z 0) of the nozzle under different inlet pressure conditions. e inlet pressure of the swirl nozzle is set to 1 MPa, 2 MPa, 3 MPa, 4 MPa, 5 MPa, and 6 MPa from small to large
Summary
Water-mist fire extinguishing technology is playing an increasingly important role in the field of modern fire protection. Pressure nozzles are widely used in fire protection because of their simple structure, large atomization angle, and production of a uniform droplet distribution [3]. Marchione et al [8,9,10] studied spray characteristics, such as the spray cone angle and the film breakage length, of the external flow field under different spray pressures. Erefore, in order to provide more research and corresponding data for reference, the characteristics of the internal flow field and the external droplet velocity distribution of a swirl nozzle are investigated in this study under medium and low pressure conditions; the internal flow profile in the swirl nozzle and the change law of the external droplet velocity are presented Few studies have been conducted to determine the characteristics of the internal flow in swirl nozzles and the external droplet velocity distribution. erefore, in order to provide more research and corresponding data for reference, the characteristics of the internal flow field and the external droplet velocity distribution of a swirl nozzle are investigated in this study under medium and low pressure conditions; the internal flow profile in the swirl nozzle and the change law of the external droplet velocity are presented
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