High-speed underwater projectiles modeling: a new empirical approach

• Published in: Journal of the Brazilian Society of Mechanical Sciences and Engineering 2015-03, Vol.37 (2), p.613-626
• Main Authors: Mirzaei, Mojtaba, Alishahi, Mohammad Mehdi, Eghtesad, Mohammad
• Format: Article
• Language: English
• Subjects: Engineering; Mechanical Engineering; Technical Paper
• ISSN: 1678-5878; 1806-3691
• DOI: 10.1007/s40430-014-0190-7

Supercavitating projectiles can achieve high speeds; however, this will pose technical challenges on their stability and flight performances. One of the most important issues which a high-speed underwater projectile (HSUP) deals with is the so-called planing force. In an ideal supercavitating flight scenario, the entire vehicle is considered to fly within the cavity walls. Nevertheless, in practice, disturbances can cause the vehicle to impact on the liquid–gas boundary. In such situations, the forces generated at the cavity boundary are referred to as the planning forces. The present paper discusses the in-flight dynamics of the HSUP. Equations of motion are developed for the projectile movements in the cavity while the tail impacts on the cavity wall. Dominant nonlinearities associated with planing forces are well thought-out in the modeling. Two available models and a new empirical model for prediction of the planning force are described. By using and combining these models, four methods are introduced and compared, through the simulation runs of supercavitated projectile flight, with two available experimental test cases.