Study On The Method Of Floating Balloon Air Tightness Detection Conditions Of Complex Atmospheric Environment

The study is originated from industry-university research cooperation project of Aviation Industry Corporation of China: Investigation on Detecting Gas Tightness of Aerostat in Complex Surroundings. The study aims to find good methods to detecting quantitatively gas leakage of aerostat manufactured by Special aircraft Research Institute of China.Gas tightness is an important technical index for aerostat, which is related to the aerostat safety, loiter time and use cost. However, it is difficult to detect the gas tightness of aerostat, especially in the complex atmospheric surroundings. A traditional way is as follows: first, the air is filled into the aerostat so that the internal pressure of aerostat is higher than the atmospheric pressure; then the difference between the internal pressure of aerostat and atmospheric pressure is measured at certain time, finally the air leakage of aerostat is derived by use of ideal gas equation of state. But the traditional way is not good since atmospheric temperature, solar radiation, etc can affect both the internal pressure of aerostat and the pressure difference of internal and external aerostat.Sometimes these factors' impact is even greater than the impact of gas leakage of aerostat. Therefore, it is necessary to study the gas tightness of aerostat in the complex atmospheric surroundings to find the factors which affect gas leakage,and establish a mathematical model by which can the leakage of aerostat can be calculated.This dissertation includes the following parts:1?The finite element model for aerostat balloon is created, and the numerical investigation on thermal characteristics of aerostat balloon at certain location and during floating without leakage is performed, then the numerical investigation on the same condition with leakage is performed.2?The gas leakage is numerically calculated at certain time at certain temperature and pressure change. In the end, the gas leakage of aerostat balloon is calculated by use of the mathematical model developed in chapter 2, and the results are verified by the numerical simulation developed in this chapter. and a lot of data collected are fused to fit the mathematical model by use of the controlled leakage method proposed in Chapter 4. which shows that the numerical simulation is reasonable.3?The inflation and deflation processes of gas in aerostat balloon are simulated, A new method——controlled leakage method for measuring leakage of aerostat balloon is put forward and the application for patent of invention based on it is granted (Patent No.:201310739123.2). More importantly, the multifunctional experiment devices are designed, the principle of which is as follows: a gas export valve is added in the balloon so that the leakage condition of aerostat balloon can be simulated by deflating gas.Because the gas deflation by export valve amplifies gas leakage effect of aerostat balloon, it is easier to build the mathematical model of the air leakage quantity.4?The gas leakage testing experiment platform for aerostat balloon according to the controlled leakage method proposed in Chapter 2 is established. The application for patent of invention named 'Gas Leakage Testing Experiment Platform for Aerostat Balloon(Patent Application No.: 2013107328563 )' is granted and The application for patent of invention named 'Wind Generating Device for Leakage Testing Experiment Platform for Aerostat balloon' based on the experiment platform is under substantive examination (Patent Application No.: 2013107328332 ). Moreover, the pneumatic system, controlling system and the software of data acquisition of experiment platform are designed and established. And the accuracy of the experimental device is analyzed and the uncertainty evaluation is made.5?The parameters during controlled leakage processes of aerostat balloon are measured by use of the gas leakage testing experiment platform,and a lot of data collected are fused to fit the mathematical model by use of the controlled leakage method proposed in Chapter 4. Moreover, the numerical simulation in Chapter 3 is verified by the experimental results, and the controlled leakage equation of aerostat balloon is derived. The comparison between both the experimental and numerical results are made,which shows that the numerical simulation is reasonable. Moreover,the numerical simulation in Chapter 3 is verified by the experimental results, and the controlled leakage equation of aerostat balloon is derived. The comparison between both the experimental and numerical results are made.