Experiment Study Of The Improved Fire Fighting Hydraulic Giant

Directing against the problems of the current fire fighting giant in China, according to turbulence theory of hydromechanics and aerodynamics theory, the project of the improved fire fighting water giant is provided in the thesis. The improved fire fighting water giant consists of stabilizer, self-excited oscillation pulsed jet nozzle and transition connections etc.Setting forth the development process of fire fighting water giant and its current situation, the technical project of which pulsed jet instead of continuous jet to improve fire fighting water giant is provided.The thesis briefly discussed the mechanism of self-excited oscillation pulsed nozzle, according to shear layer theory and stability theory, the characteristic of shear flow and the mechanism to produce, amplify and feedback the disturbances wave in oscillating cavity are analyzed. The velocity equations of shear flow in cavity are analyzed .The amplifying mode of the disturbance wave is the space mode. The amplifying factor is very dependent on the frequency of the disturbance, the length of the cavity and the state of the shear flow. The effective feedback condition has been established. The mathematical model of incompressible, two-dimension liner of vortex for the interaction of the discrete vortex with the impinging edge is put forward. The free shear layer instability to amplify disturbances is independent of originality disturb amplitude value; Reynolds number and Mach number only depended on Strouhal number. The digital computation of Strouhal number is discussed. The influence of the geometrical parameters for self-excited oscillation pulsed jet nozzle and its performance have been examined by the test. The structure parameters of self-excited oscillation pulsed jet nozzle in fire fighting water giant have been established.To improve the extinguish effect of fire fighting water giant; a stabilization device is installed in the fire fighting water giant. The motional performance of fluid in the duct of water giant is analyzed. The author proposed that the honeycombing stabilizer is adopted in the duct of water giant, and the parameter for the stabilizer put forward.Under the same condition, the site test indicates that the jet of the improved water giant spout with the pulse as if a continue series of water bombs, and the offdistance of the jet has been improved. The recoil force of water giant is reduced, and the operator feels relax.