Changing and optimizing the projectile nose shape is an important way to achieve specific ballistic performance.One special ballistic performance is the embedding effect,which can achieve a delayed high-explosive reac...Changing and optimizing the projectile nose shape is an important way to achieve specific ballistic performance.One special ballistic performance is the embedding effect,which can achieve a delayed high-explosive reaction on the target surface.This embedding effect includes a rebound phase that is significantly different from the traditional penetration process.To better study embedment behavior,this study proposed a novel nose shape called an annular grooved projectile and defined its interaction process with the ductile metal plate as partial penetration.Specifically,we conducted a series of lowvelocity-ballistic tests in which these steel projectiles were used to strike 16-mm-thick target plates made with 2024-O aluminum alloy.We observed the dynamic evolution characteristics of this aluminum alloy near the impact craters and analyzed these characteristics by corresponding cross-sectional views and numerical simulations.The results indicated that the penetration resistance had a brief decrease that was influenced by its groove structure,but then it increased significantlydthat is,the fluctuation of penetration resistance was affected by the irregular nose shape.Moreover,we visualized the distribution of the material in the groove and its inflow process through the rheology lines in microscopic tests and the highlighted mesh lines in simulations.The combination of these phenomena revealed the embedment mechanism of the annular grooved projectile and optimized the design of the groove shape to achieve a more firm embedment performance.The embedment was achieved primarily by the target material filled in the groove structure.Therefore,preventing the shear failure that occurred on the filling material was key to achieving this embedding effect.展开更多
During the displacement of water plugging with binary flooding in internally heterogeneous reservoirs,it is essential to understand the distributions of remaining oil as well as the oil displacement mechanisms at diff...During the displacement of water plugging with binary flooding in internally heterogeneous reservoirs,it is essential to understand the distributions of remaining oil as well as the oil displacement mechanisms at different stages.In this study,two types of internally heterogeneous systems,i.e.,vertical and horizontal wells are investigated experimentally through a microscopic approach.The results show that plugging agent types have a greater impact on oil recovery than well types,and foam injection can enhance oil recovery more effectively than gel injection.Additionally,the injection sequence of plugging agents significantly affects oil displacement efficiency.Injecting gel after foam is more beneficial.According to the present results,the main formation mechanisms of remaining oil in each displacement stage are influenced by:capillary force,viscous force,inertial force,shear force,microscopic fingering&channeling.展开更多
基金The financial support of this research is from the National Natural Science Foundation of China(NSFC)[No.11472053 and 11872121].
文摘Changing and optimizing the projectile nose shape is an important way to achieve specific ballistic performance.One special ballistic performance is the embedding effect,which can achieve a delayed high-explosive reaction on the target surface.This embedding effect includes a rebound phase that is significantly different from the traditional penetration process.To better study embedment behavior,this study proposed a novel nose shape called an annular grooved projectile and defined its interaction process with the ductile metal plate as partial penetration.Specifically,we conducted a series of lowvelocity-ballistic tests in which these steel projectiles were used to strike 16-mm-thick target plates made with 2024-O aluminum alloy.We observed the dynamic evolution characteristics of this aluminum alloy near the impact craters and analyzed these characteristics by corresponding cross-sectional views and numerical simulations.The results indicated that the penetration resistance had a brief decrease that was influenced by its groove structure,but then it increased significantlydthat is,the fluctuation of penetration resistance was affected by the irregular nose shape.Moreover,we visualized the distribution of the material in the groove and its inflow process through the rheology lines in microscopic tests and the highlighted mesh lines in simulations.The combination of these phenomena revealed the embedment mechanism of the annular grooved projectile and optimized the design of the groove shape to achieve a more firm embedment performance.The embedment was achieved primarily by the target material filled in the groove structure.Therefore,preventing the shear failure that occurred on the filling material was key to achieving this embedding effect.
文摘During the displacement of water plugging with binary flooding in internally heterogeneous reservoirs,it is essential to understand the distributions of remaining oil as well as the oil displacement mechanisms at different stages.In this study,two types of internally heterogeneous systems,i.e.,vertical and horizontal wells are investigated experimentally through a microscopic approach.The results show that plugging agent types have a greater impact on oil recovery than well types,and foam injection can enhance oil recovery more effectively than gel injection.Additionally,the injection sequence of plugging agents significantly affects oil displacement efficiency.Injecting gel after foam is more beneficial.According to the present results,the main formation mechanisms of remaining oil in each displacement stage are influenced by:capillary force,viscous force,inertial force,shear force,microscopic fingering&channeling.
