Study On Thermal Characteristics Of Aerostat Ballonet

Aerostat can stay in the air for a long time and has a strong viability, it has a broad application prospect in the scientific research, civil, military and other fields. The thermal characteristics of aerostat ballonet and the gas tightness of ballonet are related. The gas tightness of ballonet determines the flying time of aerostat, it is crucial to the design process of aerostat. To researh the thermal characteristics of ballonet, the methods of theoretical formula, numerical simulation and experimental study are used in this dissertation, with the single spherical ballonet aerostat as the research object.The complex heat transfer behavior of ballonet under different working conditions is studied when the gas is not leaking in this dissertation. The model of atmospheric environment,convective heat transfer and radiation related to the thermal characteristics of ballonet are established. Considering the complexity of the external environment,the average convective heat transfer coefficient and the amount of received radiation are calculated by the heat transfer formula. The thermal characteristics of ballonet under different working conditions is simulated by FLUENT. The influences of date, region, wind speed, the heat radiation characteristics of material of ballonet, altitude and off course on the thermal characteristics of ballonet is researched. The effection of fixed height, absorption rate and emissivity on the thermal characteristics of ballonet (the average of maximum temperature of ballonet surface and the maximum temperature difference of ballonet surface),is researched by range analysis. The mathematical equation between different conditions (fixed height, absorption rate and emissivity) and the thermal characteristics of ballonet (the average of maximum temperature of ballonet surface and the maximum temperature difference of ballonet surface) is established by stepwise regression analysis. The experiments of the thermal characteristics of ballonet are carried out in the lab of aerostat ballonet under different environments. The reliability of the method of numerical simulation is proven by comparing the experimental results with the simulation results.