Experimental study of two tandem cylinders entering the water obliquely was carried out based on high-speed camera in this paper.Cavitation evolution characteristics and movement characteristics of the tandem cylinders were analyzed.The results show that when the time interval is 3.5ms,cylinder Ⅱ(the front cylinder)enters the cavity of cylinder Ⅰ(the later cylinder)after entering the water,and collides with cylinder Ⅰ.According to the principle of independent expansion,cylinder Ⅰ undergoes instantaneous acceleration after being impacted,resulting in rapid expansion of cavity in the cross-section at the impact location,forming a nested cavity.The collision disrupts the stability of two cylinders,causing them to flip over in the water.When the time interval increases to 10.2-31.8 ms,cylinder Ⅱ enters the cavity of cylinder Ⅰ after entering water without colisding with the cylinder Ⅰ.Cylinder Ⅱ enters water again after penetrating the cavity wall of cylinder Ⅰ.The resistance to the motion of cylinder Ⅱ in the cavity is significantly lower than that in water,so cylinder Ⅱ has good speed storage performance.When the time interval is 48.2 ms,the tail of the cavity of cylinder Ⅰ drifts up significantly with the effect of buoyancy.The repulsion between the cavity walls of two cylinders causes the trajectory of cylinder Ⅱ to shift under pressure,and cylinder Ⅱ does not enter the cavity of cylinder Ⅰ after entering the water.The movement characteristics of the cylinder Ⅱ after entering the water are similar to that of a single cylinder,indicating that the disturbance of the flow field after the cylinder Ⅰ enters the water has little effect on the cylinder Ⅱ.However,as the cylinders move downward,the interaction between the cavity of cylinder Ⅰ and that of cylinder Ⅱ affects the attitude of the cylinder Ⅱ moving in the water.
two tandem cylindersentering water obliquelytime intervalcavitation evolutionmovement characteristics
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