Study On Self-regulating Mechanism And Flow Field Optimization Of Self-adaptive Fire Water Monitor

Fire water monitor is a kind of equipment that can put out a fire by injecting high-speed water.Compared with the well-known international fire water monitor manufacturers such as TFT and Akron in the United States,fire water monitor manufactured by domestic enterprises has smaller range,higher pressure and poorer extinguishing effect under the same flow rate.Self-adaptive fire water monitor can automatically adjust the muzzle opening under different flow conditions,so as to adjust the flow velocity and flow field status at the exit.To research the self-adjusting mechanism and to optimize hydraulics performance of self-adaptive fire water monitor will help to make its range and working pressure under different flow conditions meet or exceed the requirements of national standard,which can improve the core competence of fire water monitor products in our country.According to the empirical formula of hydrodynamics and the previous simulation results of our research group,the calculation method of internal energy loss of self-adaptive fire water monitor is determined.Based on the three basic equations of fluid mechanics,namely Bernoulli equation,continuity equation and momentum equation,the self-adjusting mechanism model of self-adaptive fire water monitor is established and the calculation method of muzzle opening under different flow rates is determined.The internal energy loss,the inlet pressure of the monitor head and the muzzle opening of self-adaptive fire water monitor are analyzed.Under different flow conditions,the frictional head losses are small,and the local head losses of the elbow and the flow stabilizer are large,and both increase with the increase of the flow rate.When the flow rate increases,the increasing trend of the inlet pressure of the monitor head accelerates gradually,and the the increasing trend of the muzzle opening decreases gradually.The experimental device of testing the muzzle opening is designed.The correctness of the self-adjusting mechanism model is verified by comparing the theoretical and experimental results.At the same time,it provides the initial conditions for the simulation of the flow field of self-adaptive fire water monitor.The main evaluation indexes of the flow field performance of self-adaptive fire water monitor are determined,namely the form of streamline,the pressure differential between the entrance and the exit,the average turbulent kinetic energy of outlet,reaction force and reaction torque.The influence of the rectification devices on the flow field performance of self-adaptive fire water monitor is analyzed by using the flow field simulation method.The result shows that circumfluence in the flow field at the exit of the monitor head decreases obviously when the deflector and the flow stabilizer are installed simultaneously,and the pressure differential between the entrance and the exit and the average turbulent kinetic energy of outlet are significantly reduced.With the main structures of self-adaptive fire water monitor as three factors,namely the shape of the monitor core,the form of the flow stabilizer and the runner structure of the entrance of the monitor head,an orthogonal experiment is designed.As a result,the best combination of the three factors is determined.Based on the structure of self-adaptive fire water monitor determined by the orthogonal experiment,a new prototype is designed and manufactured.Through experiments,it can be seen that the range of the optimized self-adaptive fire water monitor is increased by more than 2.2% compared with the range of unoptimized self-adaptive fire water monitor.Besides,the working pressure decreases under certain flow conditions.