北半球高空大气参数波动对临近空间飞行热环境的影响

Effect of atmosphere parameter oscillation at high altitude in the northern hemisphere for near space hypersonic flight aerothermodynamic prediction

真实的大气参数随时间和地理位置变化,而且有随机性的大气波动叠加,处于波动状态,造成高超飞行器大气层飞行面临的真实热环境,远比标准大气模型预测结果复杂得多.在70 km以上大气参数变化尤其复杂.本文利用美国TIMED卫星在2002~2010年8年间对北半球典型纬度地区上空85 km高度大气参数在典型月份期间内的实测统计结果,开展了大气参数分布特性对飞行器热环境具有代表性的驻点热流的影响研究.研究发现大气的波动对高超飞行的热环境有着重要和复杂的影响.同纬度地区4月或7月的热流会偏大,在同一季节,高纬度地区的热流分布往往会大于低纬度地区.在极端情况下,热流会比标准大气参数模型预测的热流高40%以上.

For real atmosphere parameter fluctuates from the standard atmosphere model according the time and geography with stochastic atmospheric wave, it is important to predict the deviation effect on the aerothermodynamics environment for gliding hypersonic vehicle. However, according to the experts at NASA Johnson Space Center, at present neither the standard atmosphere model or the reference atmospheric model is able to describe the complex real atmosphere accurately. Especially, above 70 km altitude, the atmosphere parameter varies complicatedly, and deviates from standard atmosphere model intensely. The measurement results of atmosphere parameter from SABER （Sounding of the Atmosphere using Broadband Emission Radiometry） on TIMED satellite, launched at 2001, are testified widely with data from other sources. In this paper, based on measurement results between 2002 and 2010 from SABER on TIMED satellite, the atmosphere parameter statistics characters for 85 km altitude in typical months （January, April, July and October） and typical northern latitudes （0°, 20°, 40°, 60°, 80°） are obtained. In every research case, over 5000 stochastic samples are produced, which are satisfied with Max-Min distributing or normal distributing for the atmosphere model. The heating transfer on stagnation for stochastic sample in the on-the-spot survey parameter has been also studied. Then the statistics characteristics of the heating transfer on stagnation can be obtained and compared with the results based on U.S.1976 standard atmosphere, which shows the atmosphere oscillation statistics effect. The effect for latitudes and seasons on aerothermodynamics prediction has been investigated. It is shown that fluctuation for the atmosphere parameter plays an important role on the aerothermodynamics environment in near space flight. In the high altitude zone, season factor has a notable effect on the heating distribution. However, close to the equator, season factor has a little effect. At the same reason, heating transfer in higher altitude zone is usually greater than that from the standard model; on the contrary, heating transfer in lower altitude zone is general lower than that from the standard model. In summer （July）, the higher latitude zone locates, the higher heating distribution it gets. The maximum heating transfer appears in July on 80° latitude. In extreme case, the maximum stagnation heating exceeds the result from the standard atmosphere model about 40%. At the same altitude, the maximum heating transfer appears in April or July. In the future work, the affection about the difference between Northern and Southern Hemisphere, between ocean and land and atmosphere parameter relativity will be researched.