Numerical Simulation And Experimental Research Of Seven-nozzle With Water Mist

China has been the prime incentive of global economic growth since its growing importance in international arena.The fire prevention work in China has then developed rapidly by China's increasing participation in international activities,such as its accession into WTO,the successful holding of the Olympic Games in 2008 and the APEC conference in2014.On the fire prevention work,the fire-fighting system plays a significant role,being the most effective means to secure people's life and property.And water fire suppression system is one of the most widely used and newly developed fire-fighting systems,being zero pollution,high fire extinguishing efficiency and minimum quantity of water requirements and wide range of protection.As a promising and frontier subject in the fire-fighting work,it has been under continuous study by fire research institutes and manufactures both abroad and in China and great achievements and precious experience have been made.Being the core and key part of Water Mist Fire Suppression System,the water mist nozzle decides the performance of the fire-fighting system.Still,there has a great gap to realize the ideal atomizing effect in practice,therefore,it is of great necessity to study the system and atomizing effect of water mist nozzle.By making a comparative study between the single-nozzle with water mist and the multi-nozzle with water mist,we learn that both of them have limitations.For example,the single-nozzle has a small protection radius,and the multi-nozzle is too big in size and in flow coefficient.On the basis of that,this study analyzes the main characteristic parameters and their influential factors of water mist nozzle,and devises a new type of water mist nozzle---seven-nozzle with mixed swirl water mist.It is consist of an intake on the top and two oblique intakes in both sides,and an orifice on the center of the bottom,and six lateral orifices with 60° from each other located on the same circle.The intake on the top is designed to offer enough axial momentum for jet flow so as to realize total fire extinguishing.Two oblique intakes are designed to supply impact force for perpendicular incidence flow in the mixed flow field.The incidence rotational flow produced in that field could supply enough axial momentum for the jet flow.In such a way,the angle of atomization will be enlarged.The seven orifices are structured to enlarge the atomization angle of the nozzle.Due to the complexity of atomization process and mechanism of the water mist nozzle,the establishment of the model and the process of statistical analysis should be done under the guidance of rich knowledge about mathematics and the fluid mechanics.At present,there are only several approximate mathematical model describing this kind of fluid field.Therefore,experiment plays an important part in designing and producing the water mist nozzle.This study optimize the parameters of the seven-nozzle with water mist by making theoretical research and numerical simulation as well as experimental verification.By using the software CFX,the author makes simulations on the nozzle with different structure under the same pressure and discusses the structural parameter's influence over the atomization effect.On the basis of the simulation,the author attempts to optimize the structure.Moreover,the author studies the nozzle's spray pattern in practice and analyzes the reasons for inferior performances so as to further optimize the nozzle.During the experiment,the author pays close attention to the atomization angle,the flow coefficient K,and the jetting range.The experiments show that an ideal atomization angle and jetting range could be realized when the nozzle is provided with limited high pressure and when the flow is supplied with enough motion.Provided with that,the nozzle could enlarge its range of fire extinguishing.Therefore,such kind of nozzle has a promising application prospect.