Study On Blasting Energy Of Aircraft Tire And Dynamic Response Of Burst Debris

Airplane is one of the most important transportations in the world,and also one of the most significant military equipments.As a vital role in the process of taking off and landing,aircraft tire supports all the weight of airplane and rolls on the runway.The security and reliability of aircraft tire relates directly to the aircraft safety and the safety of people's lives and properties on board.At present,although the tire burst mode has been defined in airworthiness standards,some defects exist.For example,when the aircraft tire bursts,the velocity of the debris will be significantly increased,rather than consistent with that of tire as airworthiness standards because of the impact of internal pressure.The pressure attenuation formula of High-speed gas jet in the process of tire burst is not universal,lacking the simulation under real environment of taking off and landing and the recognition to the hazard of dynamic pressure.In addition,the process of tire burst experiment is extremely sophisticated and operated difficultly,causing related research is seldom reported.In summary,studies on aircraft tire blasting have been carried out,and the main research of this thesis can be described as the follows:(1)To aim at studying the model of debris hazard,the model of dynamic response of burst debris under internal pressure releasing was simulated by using dynamic grid and user defined function in Fluent and the dynamic response program was coded by using the user defined function.According to the analysis,the dynamic process of debris can be decomposed into two stages:acceleration phase under the impact of internal pressure releasing and deceleration motion phase under air resistance.The real-time pressure difference between both sides of debris,was regarded as the only power source of the simplified physical burst model to analyze the velocity of debris,the flow field pressure and velocity changes affected by internal pressure,making up the deficiency of the mathematical model without considering the balance of internal and external pressure,which can provide numerical reference for predicting the energy of debris after bursting and the energy of burst airflow.(2)As for the model of high-speed gas jet,the real aircraft landing module and geometric model of tire were taken into account.The model of high pressure gas jet produced by internal tire pressure releasing in air flow field of landing module was built by computational fluids dynamics methods which include RANS mixing method in computing aspect,standard k-e turbulence model widely used in engineering application,and wall-function method as near wall treatment etc.The numerical simulation of various physical norms of fluids in landing module during tire burst process was realized by using flow field analysis in Fluent to solve the physical response like the gas pressure and velocity distribution in flow field after tire burst,which could predict the attenuation curve of tire internal gas after tire burst,obtain the high pressure jet flow motion status with the energy,estimate destructive ability and put forward the theory basis so as to take precautions effectively against tire burst accident in landing module.This article mainly includes three innovations.Firstly,numerical simulation adopted the combination of local remeshing method and spring deformation method and the combination of dynamic mesh method and the user defined function to successfully overwhelm some drawbacks like the poor quality of the grid,negative volume,the result of divergence etc.caused by large displacements of debris flying.Secondly,considering the real geometric model of aircraft tire,the model of high pressure gas jet produced by internal tire pressure releasing in air flow field of landing module was built by computational fluids dynamics methods.Thirdly,comparing the results of simulation with the results in literature,the rationality of calculating results were discussed and the recommendation of airworthiness and security was put forward.This study provides theory and technique basis for hazard of tire burst debris in aircraft field and high-speed gas jet in landing module.The result of study will make further efforts to be used in the alert system of aircraft tire accident,providing firm support for airworthiness and security.