为了解决大采高综采工作面易发生煤壁片帮及其难以控制的问题,提出了将控制煤壁片帮的切入点放在液压支架上,通过采用理论分析和数值模拟相结合的方法研究了综采液压支架初撑力为0-5 000 k N时对煤壁稳定性的影响规律。研究结果表明：...为了解决大采高综采工作面易发生煤壁片帮及其难以控制的问题,提出了将控制煤壁片帮的切入点放在液压支架上,通过采用理论分析和数值模拟相结合的方法研究了综采液压支架初撑力为0-5 000 k N时对煤壁稳定性的影响规律。研究结果表明：当液压支架初撑力由0增大到5 000 k N时,煤壁内破坏深度由3.0 m减小为1.5 m,垂直集中应力峰值减小24%,煤壁处顶板下沉量减小24mm,煤壁水平偏移量减小8 mm。现场实测结果显示,提高液压支架初撑力能有效减小煤壁片帮次数和片帮深度;改善煤壁受力状态,最终减小煤壁片帮发生的概率。展开更多
Lagwise dynamic characteristics of a wind turbine blade subjected to unsteady aero- dynamic loads are studied in this paper. The partial differential equations governing the coupled longitudinal-transverse vibration o...Lagwise dynamic characteristics of a wind turbine blade subjected to unsteady aero- dynamic loads are studied in this paper. The partial differential equations governing the coupled longitudinal-transverse vibration of the blade with large bending deflection are obtained by ap- plying Hamilton＇s principle. The modal problem of the coupled vibration is handled by using the method of numerical integration of Green＇s function. Influences of the rotating speed, the pitch angle, the setting angle, and the aerodynamic loads on natural frequencies are discussed. Results show that： （I） Lagwise natural frequencies ascend with the increase of rotating speed; effects of the rotating speed on low-frequencies are dramatic while these effects on high-frequencies become less. （2） Influences of the pitch angle on natural frequencies are little; in the range of the normal rotating speed, the first frequency ascends with the increase of the absolute value of the pitch angle, while it is contrary to the second and third frequencies. （3） Effects of the setting angle on natural frequencies depend on the rotating speed; influences are not significant at low speed, while they are dramatic on the first frequency at high speed. （4） Effects of the aerodynamic loads on natural frequencies are very little; frequencies derived from the model considering aerodynamic loads are smaller than those from the model neglecting aerodynamic loads; relative errors of the results corresponding to two models ascend with the increase of the absolute value of the setting angle.展开更多
文摘为了解决大采高综采工作面易发生煤壁片帮及其难以控制的问题,提出了将控制煤壁片帮的切入点放在液压支架上,通过采用理论分析和数值模拟相结合的方法研究了综采液压支架初撑力为0-5 000 k N时对煤壁稳定性的影响规律。研究结果表明：当液压支架初撑力由0增大到5 000 k N时,煤壁内破坏深度由3.0 m减小为1.5 m,垂直集中应力峰值减小24%,煤壁处顶板下沉量减小24mm,煤壁水平偏移量减小8 mm。现场实测结果显示,提高液压支架初撑力能有效减小煤壁片帮次数和片帮深度;改善煤壁受力状态,最终减小煤壁片帮发生的概率。
基金supported by the National Natural Science Foundation of China(Nos.11072204,11102030,11302183 and 11372257)
文摘Lagwise dynamic characteristics of a wind turbine blade subjected to unsteady aero- dynamic loads are studied in this paper. The partial differential equations governing the coupled longitudinal-transverse vibration of the blade with large bending deflection are obtained by ap- plying Hamilton＇s principle. The modal problem of the coupled vibration is handled by using the method of numerical integration of Green＇s function. Influences of the rotating speed, the pitch angle, the setting angle, and the aerodynamic loads on natural frequencies are discussed. Results show that： （I） Lagwise natural frequencies ascend with the increase of rotating speed; effects of the rotating speed on low-frequencies are dramatic while these effects on high-frequencies become less. （2） Influences of the pitch angle on natural frequencies are little; in the range of the normal rotating speed, the first frequency ascends with the increase of the absolute value of the pitch angle, while it is contrary to the second and third frequencies. （3） Effects of the setting angle on natural frequencies depend on the rotating speed; influences are not significant at low speed, while they are dramatic on the first frequency at high speed. （4） Effects of the aerodynamic loads on natural frequencies are very little; frequencies derived from the model considering aerodynamic loads are smaller than those from the model neglecting aerodynamic loads; relative errors of the results corresponding to two models ascend with the increase of the absolute value of the setting angle.
