Development Of The Wind Tunnel Simulating Stratosphere Environment

The exploration of our human extends into the sky constantly due to the fast developments of technical improvements. The stratosphere goes into sight of people with a stable weather conditions and good magnetic properties which other atmosphere environments don’t have. After entering the 21 st century, the world raised a rush of research and development of the stratosphere airship with the development of related technologies.In the 20 km height of the stratosphere, the average temperature is about-57℃and the minimum up to-75℃ which far more than the normal operating temperature range(-20 ~ + 40℃) of general electronic equipment. In addition, the air pressure is low and air density is small in 20 km which makes convective heat transfer effect poorer and heat concentration easier to form. These may influence the performance of the equipment as the temperature out of extreme. Therefore, developing a stratosphere environment(low temperature and low pressure) simulator with air pressure, temperature and speed adjustable to provide an environmental simulation test method for the electric device used in stratosphere environment is very important.In this paper, according to the design requirements, we developed a wind tunnel with adjustable air pressure, temperature and speed to simulate the stratosphere environment. The design of wind tunnel device, low temperature system, low pressure system, and test and control system is completed. The air distribution in wind tunnel test section is simulated, the actual wind tunnel is built and the performance test is successfully carried out.The performance testing results of the wind tunnel show that during the system debugging, the air pressure dropped from 101 kPa to 4kPa in about 30 minutes in wind tunnel test section, less than 45 minutes of the design requirements; the temperature of wind tunnel test section declined from 20℃ to-70℃ in about 142 minutes because of the cooling process contains the wind tunnel steel shell and internal motor device cooling; the temperature field distribution is homogeneous moderately as the biggest difference between four measuring point in wind tunnel is 1.6℃. The testing time for electric device used in stratosphere environment is about 30 minutes during the test period. In this period, the air pressure, temperature and speed can keep stable in all conditions; the fluctuations are in the range of the design requirements. The wind tunnel operates reliable and can be used for the performance test of electric device which used in stratosphere environment and provide an environmental simulation test method for the electric device.