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摘要: 进行了速度在35~160m/s的平头、卵形和截卵形弹体入水实验,利用高速相机记录了弹体入水 和空泡扩展的详细过程,得到了3种弹体在入水初期的水中弹道轨迹和空泡形状,并比较分析了弹体头部形 状对入水弹道稳定性的影响。结果表明,平头弹体在水中飞行有良好的弹道稳定性,截卵形弹体往往由于受 力不均衡在入水后期发生偏转,卵形弹体则在入水前期即发生偏转。假定弹体入水过程中的阻力系数为非定 值,修改了柱形弹体水中速度衰减数学预报公式,同时根据能量守恒建立了平头弹体入水的空泡形状模型,计 算结果与实验结果吻合良好。Abstract: Water-entryexperimentswereconductedinthevelocityrange35~160m/sfortheprojectilesofthethreedifferentgeometriesincludingflatnose, truncated-ogivalnoseandogivalnose.A digitalhigh-speedcamerawasusedtorecordthedetailedprocessesofwaterentryandcavityexpansion andobtainthehydro-ballistictrajectoriesandcavityshapesintheearlystagesofwaterentryforthe projectilesofthethreedifferentgeometries.Andtheeffectsofthenoseshapesonthehydro-ballistic stabilitieswerecomparedamongtheprojectilesofthethreedifferentgeometries.Comparisonsindicatethattheflatnoseprojectilehasgoodhydro- ballisticstabilityinthewater,thetruncated-ogival noseprojectilewilldeflectinthelatestageofwaterentrywhichisresultedfromthedeflectingforce ontheprojectilenose,bycontrary,theogivalnoseprojectilewilldeflectintheearlystageofwater entrywhichhastheworststability.Byconsideringthecavitationnumberwasavelocity-dependent factor,amodifiedmathematicalmodelwasproposedtopredictthevelocityattenuationofcylindrical projectilesandacavitydimensionmodelwaspresentedbasedontheenergyconservation.Thecalculationsareingoodagreementwiththeexperimentalresults.
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Key words:
- fluidmechanics /
- hydro-ballisticstability /
- velocityattenuation /
- high-speedwaterentry /
- cavityshapes
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