We determi：ned a suitable gate road layout in slice mining in an ultra-thick unstable coal seam, using theoretical anallysis and numerical calculations. Based on plasticity theory in terms of limiting equilibrium, th...We determi：ned a suitable gate road layout in slice mining in an ultra-thick unstable coal seam, using theoretical anallysis and numerical calculations. Based on plasticity theory in terms of limiting equilibrium, the width of chain pillar in the upper slice was calculated to be 18 m. The stress distribution in the chain pillar after the upper slice was mined out was described with numerical simulation. The extent of the effect of stress on the upper chain pillar on the lower solid coal was obtained on the basis of an elastic solution of a distributed force loaded on a half-plane. Three layout designs for lower gate roads were pro- posed and a stability factor was introduced to analyze the stability of the lower pillar with numerical calculation. Gate road translation was determined as the most suitable layout method, which maximizes the extraction rate on the basis of the pillar stability.展开更多
The unsteady phenomena in the transonic flow around airfoils are observed in the flow field of fan, compressor blades and butterfly valves, and this often causes serious problems such as the aeroacoustic noise, the vi...The unsteady phenomena in the transonic flow around airfoils are observed in the flow field of fan, compressor blades and butterfly valves, and this often causes serious problems such as the aeroacoustic noise, the vibration. In the transonic or supersonic flow where vapour is contained in the main flow, the rapid expansion of the flow may give rise to a non-equilibrium condensation. However, the effect of non-equilibrium condensation on the transonic internal flows around the airfoil has not yet been clarified satisfactorily. In the present study, the effect of non-equilibrium condensation of moist air on the self-excited shock wave oscillation on a circular arc blade was investigated numerically. The results showed that in the case with non-equilibrium condensation, frequencies of the flow oscillation became smaller than those without the non-equilibrium condensation.展开更多
基金provided by the Research Fund of the Fundamental Research Funds for the Central Universities of China University of Mining & Technology (No. 2010ZDP02B02)the State Key Laboratory of Coal Resources and Mine Safety (No.SKLCRSM08X2)+2 种基金the Jiangsu "333"High Qualified Talentsthe National Natural Science Foundation of China (Nos. 50904063 and51004101)the Scientific Research Foundation of China University of Mining & Technology (Nos. 2008A003 and 2009A001)
文摘We determi：ned a suitable gate road layout in slice mining in an ultra-thick unstable coal seam, using theoretical anallysis and numerical calculations. Based on plasticity theory in terms of limiting equilibrium, the width of chain pillar in the upper slice was calculated to be 18 m. The stress distribution in the chain pillar after the upper slice was mined out was described with numerical simulation. The extent of the effect of stress on the upper chain pillar on the lower solid coal was obtained on the basis of an elastic solution of a distributed force loaded on a half-plane. Three layout designs for lower gate roads were pro- posed and a stability factor was introduced to analyze the stability of the lower pillar with numerical calculation. Gate road translation was determined as the most suitable layout method, which maximizes the extraction rate on the basis of the pillar stability.
文摘The unsteady phenomena in the transonic flow around airfoils are observed in the flow field of fan, compressor blades and butterfly valves, and this often causes serious problems such as the aeroacoustic noise, the vibration. In the transonic or supersonic flow where vapour is contained in the main flow, the rapid expansion of the flow may give rise to a non-equilibrium condensation. However, the effect of non-equilibrium condensation on the transonic internal flows around the airfoil has not yet been clarified satisfactorily. In the present study, the effect of non-equilibrium condensation of moist air on the self-excited shock wave oscillation on a circular arc blade was investigated numerically. The results showed that in the case with non-equilibrium condensation, frequencies of the flow oscillation became smaller than those without the non-equilibrium condensation.
