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与位置有关正态时间函数模型构建及参数 被引量:1
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作者 贺福帅 胡海峰 +1 位作者 廉旭刚 张凯 《煤炭学报》 EI CAS CSCD 北大核心 2020年第S02期766-772,共7页
动态预计为煤炭开采过程中工作面上方的建构筑物保护提供依据,时间函数作为动态预计的核心尤为重要。传统时间函数研究对象为单点,对开采过程中时间参数随位置变化规律研究不足。基于正态分布时间函数具有较好的时空完备性,通过引入超... 动态预计为煤炭开采过程中工作面上方的建构筑物保护提供依据,时间函数作为动态预计的核心尤为重要。传统时间函数研究对象为单点,对开采过程中时间参数随位置变化规律研究不足。基于正态分布时间函数具有较好的时空完备性,通过引入超前影响距L1和最大下沉速度滞后距L2,在优化后的正态时间函数基础上建立了与位置x有关的时间函数模型并给出了参数开始移动时间tp和移动持续时间tc的计算公式。结合某工作面走向点实测数据,运用最小二乘拟合法探究了形态参数c随位置x的变化规律,并选取不同地质条件下的工作面验证规律可靠性。研究结果表明:形态参数c在模型范围内分为两段,第1段表现为减函数,第2段为稳定值,分界点为超前影响距与充分采动距之和。拟合参数代入模型后,将观测点预测值与实测值比较,预测相对中误差保持在5%~9%;在较软弱地质条件下的另一工作面,预测相对中误差保持在1%~5%。正态时间函数单点精度优于或等于传统的Knothe时间函数、双参数Knothe时间函数、Logistic函数,且模型整体精度稳定,精度能够满足实际预测需要。通过处理工作面实测数据,将预测值与实测值对比,其相对中误差在合理范围内,证实了模型的可靠性。因此正态分布时间函数模型可为矿区地表沉陷精确动态预计服务。 展开更多
关键词 开采沉陷 超前影响距 最大下沉速度滞后距 正态时间函数 参数
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Numerical Modelling of a Supersonic Axial Turbine Stator
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作者 Aki Grnman Teemu Turunen-Saaresti +1 位作者 Ahti Jaatinen Jari Backman 《Journal of Thermal Science》 SCIE EI CAS CSCD 2010年第3期211-217,共7页
In order to improve the turbocharging process,a supersonic axial turbine stator was modelled numerically with a pulsatile inlet mass flow.The main objectives of the study were to find out how pulsation affects the flo... In order to improve the turbocharging process,a supersonic axial turbine stator was modelled numerically with a pulsatile inlet mass flow.The main objectives of the study were to find out how pulsation affects the flow field and the performance of the stator.At the beginning of the study,a supersonic turbine stator was modelled using three different techniques:quasi-steady,time-accurate with constant boundary conditions and time-accurate with a pulsatile inlet mass flow.The time-averaged and quasi-steady flow fields and performance were compared,and the flow field and stator performance with a pulsatile inlet mass flow was studied in detail at different time-steps.A hysteresis-like behaviour was captured when the total-to-static pressure ratio and efficiency were plotted as a function of the inlet mass flow over one pulse period.The total-to-static pressure ratio and efficiency followed the sinusoidal shape of the inlet flow as a function of time.It was also concluded that the stator efficiency decreases downstream from the stator trailing edge and the amplitude of the pulsating mass flow is decreased at the stator throat. 展开更多
关键词 CFD SUPERSONIC TURBINE STATOR TURBOCHARGING
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