简介：Amethodispresentedtodeterminesignificantfrequenciesofoscillationsofcavitationstructuresfromhigh-speedcamerarecordingsofaflowarounda2-Dhydrofoil.ThetopviewofthesuctionsideofanNACA2412hydrofoilisstudiedinatransparenttestsectionofacavitationtunnelforselectedcloudcavitationregimeswithstrongoscillationsinducedbytheleading-edgecavityshedding.Theabilityofthemethodtoaccuratelydeterminethedominantoscillationfrequenciesisconfirmedbypressuremeasurements.Themethodcanresolvesubtleflowcharacteristicsthatarenotvisibletothenakedeye.Themethodcanbeusedfornoninvasiveexperimentalstudiesofoscillationsincavitatingflowswithadequatevisualaccesswhenpressuremeasurementsarenotavailableorwhensuchmeasurementswoulddisturbtheflow.

简介：为了保证矿山安全高效开采,通过分析影响采场稳定性关键因素及破坏机理,应用数值模拟法对二步矿柱在不同结构参数和两侧不同充填配比开采条件的稳定性进行分析,优选出安全高效的一步采场充填配比和二步采场的结构参数。采用FLAC3D数值模拟,计算和分析在开采过程中,不同结构参数和两侧不同充填配比的采场顶板的应力、应力分布区域面积及位移变化特征,得出各不同方案的采场顶板稳定情况。结果表明：采场受两侧充填体配比的影响较为明显,一步采场灰砂比由1∶6改变到1∶8时,对二步采场的稳定性影响较小;灰砂比小于1∶8和采场宽度大于18m时,采场顶板的拉应力和位移的变化率逐渐变大,采场的稳定性迅速降低。因此,综合矿山生产安全、高效及成本考虑,建议一步采场充填配比为1∶8、二步采场的宽度为18m。