The feature of stratification in the blowing sand cloud

The profiles of particle concentration in salta-tion layer versus height are calculated, by the motion equa-tious for a saltating grain in conjunction with different probability distribution functions of the vertical liftoff ve-locities of grains and an empirical expression of wind velocity.The numerical results demonstrated that the stratification phenomenon exists in the particle concentration profiles and showed increasing, saturating and decreasing features, re-spectively, when the probability distribution functions of liftoff velocities adopted in the calculation are similar to a normal distribution or a two-parameter gamma distribution.When the distribution function of lifleff velocities is taken as an exponential form, the profde of particle concentration decreases monotonically. A numerical simulation of mass flux of grains, performed by the model suggested in this paper, is in reasonable accordance with the measured data.     

传感器提离值对管道漏磁检测的影响

为了提高油气管道漏磁检测的准确度,需要在确保检测灵敏度的同时,减小磁传感器与被测油气管道表面的距离即提离值的波动的影响。分析了提离值选择的主要原则,并从磁路设计角度,提出了一种通过改进油气管道检测器结构抑制传感器提离值波动影响的方法。通过仿真计算验证了这种方法的效果。结果表明:该方法不仅可以有效地提高检测灵敏度,而且信噪比可以提升30%以上。该方法有助于为优化检测器结构和提高漏磁检测的准确度提供重要的依据。     

喷射火的双向人工扰流脱火效能研究

针对目前喷射火的施救方法存在效率低、代价高等缺陷,结合燃烧的脱火机理,提出了双向人工扰流脱火施救法,定义了双向人工扰流脱火三原理,并对其技术优势进行了分析,进而专门设计了实验装置并开展了脱火效能实验研究。实验结果表明：在相同的实验条件下,双向人工扰流相比单向人工扰流,最大脱火距离明显提高,并且两者呈相同的变化规律;在相同功耗条件下,双向人工扰流的脱火距离大于单向人工扰流;单双向人工扰流入射角度较小时均不能使火焰脱开,入射角度为30?时,火焰脱开距离最大,之后随着入射角度的增大逐渐减小。     

跃移层中沙粒浓度分布特征的研究

对于不同的沙粒起跳初速度分布函数，利用数值方法模拟了沙粒浓度沿高程的分布规律，发现风沙强度沿高程具有“递增－饱和－衰减”的按层分布的规律，进一步详细研究了影响风沙流结构的主要因素，如风速分布、地表粗糙度、沙粒粒径等对风沙流结构的影响方式和规律。