Research On Internal Thermal Environment Of Air-supported Membrane Structure Considering Thermal Performance Of Membrane

In recent years,air-supported membrane structures have been more and more used in large space structures due to their good mechanical properties,economy and environmental protection characteristics.In the past,studies on membrane material and air-supported membrane structures mostly focused on mechanical properties.There is little research on thermal performance of membrane material and indoor thermal environment of air-supported membrane structures.However,the membrane material is very thin and light,and the changes of outdoor temperature,sunshine radiation and other environment greatly affect the thermal environment inside the air-supported membrane structures and the comfort of personnel activities.Therefore,it is necessary to carry out relevant research.Based on the above research background,the paper mainly carries out the following aspects:1.The thermal performance of membrane material was tested.Firstly,the thermal radiation property of single layer membrane is tested based on spectrum method,and the reflection,transmission and absorption coefficient of fabric membrane to sunlight are given.It is found that coating and color have a great influence on the spectral reflectance ratio of membrane material.Secondly,the steady-state method and the transient method are used to test the thermal conductivity of the membrane at room temperature.The applicability of the two methods is given.Steady state method is recommended at room temperature;transient method is recommended when considering temperature changes.The influence of temperature change on thermal conductivity of membrane material was investigated.On this basis,the steady-state plate method and the protective hot box method are used to study the heat transfer performance of the multilayer composite membrane components.It is found that the thermal resistance measured by steady-state plate method is larger.2.The numerical simulation method and evaluation standard of indoor thermal environment of air-supported membrane structures are studied.The CFD numerical simulation method of indoor thermal environment is summarized and verified by two examples.Suggestions on setting flow field parameters such as model for indoor thermal environment simulation are given: RNG k-ε model is recommended for turbulence model,discrete coordinate DO model for radiation model and Boussinesq assumption for air density.On the basis of summarizing the domestic and international evaluation standards for indoor thermal environment,and considering the characteristics of internal thermal environment of air-supported membrane structures,the evaluation standards suitable for indoor thermal environment of gas film structure are concluded from three perspectives of temperature,air flow velocity and non-uniformity coefficient.3.Analysis on Indoor Thermal Environmental Impact Factors of Gas Film Ice Field.Taking a rectangular air-supported membrane structure as research object and based on FLUENT software,the influence of various indoor and outdoor factors,such as position of air outlet,number of air inlets,air inlet speed,air inlet temperature,outdoor temperature and thermal performance of membrane material,on indoor thermal environment of gas film structure is analyzed,and the distribution characteristics of indoor thermal environment of air-supported membrane structures are explored.It is found that various factors have different effects on indoor thermal environment of air film: outdoor temperature,air inlet temperature,single layer film and multi-layer film have the greatest effects,followed by air inlet speed,number of air inlets,high reflection and low light transmission and high light transmission and low reflection film,and heat shielding and non-heat shielding film,different air outlet locations have the least effects,which can be ignored.