Research On Lifting Operation Stability For Ladder Tower Fire Fighting Vehicle

At present,there are many generally problems of ladder fire fighting vehicle,such as the lack of operation safety in the face of complex harsh conditions of the fire site,and it can only be lifted up to extinguishing the fire with the support of the parking leg.In the context of the increasingly urgent demand for fire emergency rescue technology and equipment,it is difficult to meet the needs of urban safety and industrial safety.Therefore,new type carrier liquid ladder tower fire fighting vehicle was born.On the one hand,as a special vehicle equipped with both ladder top fire monitor and a tank top fire monitor,the synchronous injection of the dual fire water monitor can greatly increase the coverage space of fire fighting liquid,and realize the single vehicle three dimensional layered space fire extinguishing.On the other hand,it has a new mode of synchronous fire extinguishing with high and low fire water monitor in the moving state,which is of great significance to reduce personnel damage and improve fire extinguishing efficiency.However,in the complex mode of moving state and raising fire extinguishing,the stability of the vehicle is related to many factors.This subject is supported by the National Key R&D Program of China “Key Technology Research and Product of New Ladder Tower Fire Fighting Vehicles”(No.2016YFC0802909),this dissertation has carried out research on the ladder tower fire fighting vehicles safe operation for lifting of fire fighting This work is carried out based on fluid mechanics,finite element simulation,signal processing,virtual prototype technology and other related theories,and methods.The purpose of the corresponding research is to master the factors affecting the stability of ladder tower fire fighting vehicle fire extinguishing,and reveal the scope of safe fire extinguishing operations,so as to developed a ladder tower fire fighting vehicles with strong site applicability and outstanding fire fighting ability to provide necessary theoretical support.The main study contents of this thesis can be summarized as follows:(1)On the basis of the introduction of the whole vehicle layout and basic working principle of the ladder tower fire fighting vehicle,this dissertation analyzes the influencing factors of the ladder tower fire fighting vehicle safety fire extinguishing,as well as points out the focus of this research work.The relevant experimental platforms are constructed to carry out,which include the fire water monitor jet reaction forces test platform,the fire rescue ladder vibration test platform,and the ladder tower fire fighting vehicle tire vertical loads distribution test platform.The necessary experimental datas are supported to verify the reliability and accuracy of the research content involved in this dissertation.(2)Firstly,the study focus on characteristics of one way fluid-structure interaction of fire water monitor is carried out.In order to obtain theoretical calculation results under different operation working conditions,the solution equation of the fire water monitor jet reaction forces theory is pointed out through using the analysis theory of fluid mechanics;The one way fluid structure coupling analysis approach is proposed to realize the simulation research on the characteristics of jet reaction forces,structural deformation and stress distribution under different working conditions of inlet mass flwor rate and fire water monitor pitch angles;The accuracy of the numerical simulation results and theoretical calculation results are verified by comparing the errors with the experimental results.(3)Secondly,the research on the vibration characteristics of fire rescue ladder under different working conditions is carried out.Based on the physical model of fire rescue ladder system and finite volume method,the modelling methods of threedimensional simplified model and structural numerical simulation model are pointed out.The naural modal vibration characteristics of fire rescue ladder under different working conditions are studied based on modal analysis,prestressed modal analysis and transient dynamic analysis methods by setting effective boundary conditions and contact algorithm.The research on the influence of sudden change speed,buffer device,load mass and amplitude angles on the vibration characteristics of the fire rescue ladder was carried out through combined with the experimental test platform,and the validity of the simulation results are verified.The method of data fitting based on the results of numerical analysis is proposed to establish the prediction model of fire rescue ladder vibration frequency.(4)Finally,the study on the fire extinguishing stability of ladder tower fire fighting vehicle is carried out.Considering the complexity of the whole vehicle system structure and the difficulty of studying its dynamic characteristics,the virtual prototype simulation method is proposed to realize the construction of the parameterized virtual prototype model of the ladder tower fire fighting vehicle,and the reliability and effectiveness of the model are verified.Based on the above model and the tire vertical load of each axle as the basis,the effects of different operation parameters such as working attitude of the fire rescue ladder and the jet reaction forces of the fire water monitor on the stability of vehicle rollover working condition,uniform motion working condition,braking working condition and steady state rotation working condition are studied.The scope of safe operation of vehicle is pointed out.There are 108 figures,17 tables and 173 references in this dissertation.