Water discharge time from the conical surface of an underwater launched vehicle

• The mathematical model of the aqueous layer aerial drainage time is proposed.
• The pseudo-free surface is introduced in deriving the water discharge time equation.
• The effects of various factors on the water drainage time are examined.
• The accuracy of the water discharge time equation is validated.

During the exiting process of the underwater launched vehicle which consists of a conical portion and a cylindrical shell structure, the aqueous layer on the top of the conical surface moves with the vehicle and undergoes downwards movement along the conical surface to form an aerial drainage outside the cylinder. The instant when the aerial drainage of the aqueous layer ends is the starting time of the fluid flow around the cylindrical shell structure. This duration is extremely important from the point of view of monitoring and controlling the launched vehicle. Therefore, the investigation reported in the present paper is concerned with the analysis of the acceleration of the top aqueous layer so as to build the energy equations of flow filaments and total flow of the aqueous layer. The pseudo-free surface is introduced in the derivation of time equation of the aerial drainage of the top aqueous layer. The effects of various factors on the aqueous layer aerial drainage time are examined. The conceptual adequacy and accuracy of the derived time equation for the aqueous layer aerial drainage are validated by way of comparison between the computed results and experimentally obtained data.