Thermal Characteristics Of Sightseeing Manned Airship And Defrosting Performance Of Cockpit Windshield

Manned airship with its smooth flight,long endurance time,slow flight speed,low requirements for the takeoff and landing site will be more and more favored by the market with the opening of the low-altitude field supervision.The safety design of manned airship is significant to accelerate the process of airship becoming aerial tour vehicles.Since the manned airship liftoff depends on the density difference between the inside and outside gasbag,the temperature fluctuation of the envelope and internal floating gas caused by the environment will lead to the change of altitude and stability.Therefore,this thesis studied the thermal characteristics and defrosting characteristics of manned airship through numerical simulation.Next,the review was focused on the influence of different environment and structural parameters on its thermal characteristics.The main research contents and achievements are as follows:(1)In this thesis,a kind of capsule structure manned airship is proposed,which is composed of main helium gasbag and additional helium gasbag.Then,the mathematical models of its thermal environment are established,including atmospheric thermal model,solar radiation model,long-wave radiation model and convective heat transfer model.Afterwards,based on the thermal model,the heat balance equations of the main helium gasbag,the additional helium gasbag,the pod,the solar cells,the lower envelope of the solar cells and other envelope were established respectively.The hourly temperature of each part of the manned airship under different working conditions is solved by Runge-Kutta method and obtained by programming C++ language.(2)Through grid independence verification,the grid number of manned airship meeting the requirement of calculation accuracy was given.Then,the effects of fineness ratio,season,latitude,orientation,envelope radiation characteristics and solar cells on the temperature of each part of manned airship were analyzed.Lastly,the strategies and methods for alleviating the overheat of batteries are pointed out.(3)Based on the hydrodynamic simulation technology,the influence of different parameters on the defrost characteristics of manned airship windshield was analyzed.Concretely,the effects of single air supply outlet and double air supply outlet on frost thawing characteristics were compared.In addition,the influence rule of supply air temperature on defrosting time is given,and the direction of the optimization of supply air temperature is pointed out.Particularly,the recommended values of air supply velocity and direction are given coupled with energy consumption and frost layer phase change characteristics.The above research results have perfected the research on the stability of manned airship flight and discussed the key issues such as frosting about the cockpit windshield,it can provide a technical reference for the safety design of manned airship.