| The smoke,dust and high temperature produced by building fire are the main obstacles to carry out fire fighting.The research and development of fire fighting equipment with the functions of smoke elimination,dust reduction and temperature reduction is an important guarantee for the personal safety of firefighters and victims and for the purpose of more effective fire fighting.As a fire-fighting auxiliary equipment with good explosion-proof performance,convenient movement,smoke abatement and dust reduction,the Hydraulic smoke elimination and exhaust mechine has attracted the attention of relevant fields.In this paper,the core component of the hydraulic smoke arrester,water turbine,is taken as the research object.Based on the study of the influence of the structural parameters on the flow field characteristics and performance of the water turbine,the optimal design of the water turbine structure is studied in order to provide a reference for the research and development of the water turbine and the hydraulic smoke arrester.The main research work and conclusions are as follows:1.On the basis of comprehensive investigation and analysis,the internal flow calculation model of Water wheel is established,and the existing internal flow field of Water wheel is simulated,and the reliability of the model is verified by experiments.2.The effects of nozzle length,nozzle diameter,nozzle number,nozzle area and nozzle angle on the internal flow characteristics and efficiency of the straight nozzle water turbine are studied.The key structural parameters affecting the performance of the water turbine are analyzed to lay the foundation for the optimization of the water turbine structure.The results show that the nozzle length is one of the important factors affecting the efficiency of Water wheel,and the smaller nozzle length is easier to obtain higher efficiency;the effect of nozzle angle on the efficiency of Water wheel is obvious,the increase of nozzle angle reduces the efficiency;other parameters have relatively small impact on the efficiency of Water wheel.3.The influence of the angle between the bend and the nozzle on the efficiency of the water turbine is studied.The results show that the bend angle has a significant effect on the efficiency of water turbine,and the maximum efficiency increases first and then decreases with the increase of the bend angle;when the bend angle is less than 90 °,the maximum efficiency corresponds to the speed of 1200 rpm,and when the bend angle is greater than or equal to 90 °,the maximum efficiency gradually shifts to the condition of speed reduction.4.The relationship between the velocity ratio of straight nozzle and curved nozzle and the maximum efficiency is analyzed under different structural parameters.The speed ratio corresponding to the highest efficiency of water turbine is different under different structures,parameters and working conditions.The speed ratio of straight nozzle water turbine is between 0.59 and 0.88,the speed ratio of curved nozzle water turbine is between 0.53 and 0.82,and the overall average is about 0.7.5.The optimal design of water turbine structure is studied.The optimal variables of water turbine are determined by orthogonal test method,the sample set of water turbine optimization is established by uniform test design method,the influence of interaction between the optimal variables on water turbine efficiency is analyzed by response surface method,and the water turbine structure is optimized by genetic algorithm.The results show that the efficiency of the curved nozzle water turbine is significantly higher than that of the straight nozzle water turbine;after optimization,the efficiency of the straight nozzle water turbine is increased by 5.39 percentage points to 49.62%,and the corresponding structural parameters,such as nozzle area of 103.4mm2,nozzle diameter of 24 mm,nozzle length of 382.8mm,nozzle number of 2;after optimization,the efficiency of the curved nozzle water turbine is increased by 15.4 percentage points to 81.47%,and the corresponding structural parameters,such as nozzle area,nozzle diameter of 24 mm,nozzle length of 382.8mm The area is 109.92mm2,the diameter of the bent nozzle is 32.96 mm,the length of the bent nozzle is 480.96 mm,the angle of the bent nozzle is 75.94 °,and the number of the bent nozzles is 2. |
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