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煤与瓦斯突出矿井多松软煤层,若存在严重的喷孔现象,则会使钻孔施工过程困难重重,制约了突出矿井的瓦斯防治力度.为解决该问题,本文从软煤钻孔护壁工艺和工况参数着手,研究出一套适合严重喷孔松软煤层的钻孔施工装备,并进行了现场试验.试验证明,该套装备能有效防止钻杆对钻孔壁扰动,配以风力排渣压注式封孔和拖动式下套技术,能有效增加... 相似文献
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The flow around a gas bubble forming at a submerged orifice without vaporisation is analysed both with and without heat transfer taking place from the bubble surface. The results of experiments are given in which high-speed photography was used to study air bubbling through four different sizes of orifice into water, for the isothermal and diabatic case. A numerical solution of the dimensionless equations using Hamming's modified predictor-corrector method gave excellent agreement with experimental measurements of the bubble volume-time history for both stages of growth as well as predicting accurately the transition point between the two stages. Most of the heat transfer was found to occur almost immediately after the start of bubble growth 相似文献
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基于实测房屋模型风洞试验,分析了屋盖角部不同开孔大小和开孔形状情况下低矮房屋的风荷载特性.内外压的叠加作用使屋盖上出现了很大的正风压,内压整体分布均匀,开孔面积越小,内压作用越强;内压的概率密度接近于高斯分布,净压的非高斯特性相比于外压有所减弱;内压在频域内也表现出很强的相关性,内压谱在Helmholtz频率和漩涡脱落频率处均出现了谱峰值,净压谱中漩涡脱落作用被抵消;内压的荷载特性间接反映出迎风前缘的长度有利于锥形涡的发展,成对出现的锥形涡并非同时同步达到最强. 相似文献
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