Experimental Study on Motion Behavior and Longitudinal Stability Assessment of a Trimaran Planing Hull Model in Calm Water

Abstract

In this study, a high-speed planing trimaran hull form is designed, and the effects of different displacements and gravity longitudinal layouts on the performance of the trimaran planing hull in calm water are experimentally investigated in the towing tank of the China Special Vehicle Research Institute. Based on previous work, an innovative inner tunnel appendage hydroflap is mounted in the inner aft tunnel, located 1/8 L from the transom in the longitudinal direction with attack angles of 0° and 4°, respectively. Furthermore, a regular stern flap is mounted on the transom close to the chine. The towing test results show that, as the gravity center moves forward, the high-speed region resistance of the planing trimaran increases and the longitudinal stability is also strengthened. Further, the total resistance of the planing trimaran with a heavier displacement is larger while the average mass resistance declines; i.e., the resistance efficiency is improved. The results also indicate that the inner tunnel hydroflap and stern flap enhance the aft hull hydrodynamic lift and tunnel aerodynamic lift. As a result, mounting aft hull lift enhancement appendages can affect the bottom and inner tunnel pressure distribution and then cause a slight resistance decrease in the low-speed region. The value relationship of resistance between groups of appendages for the attached hull and bare hull is reversed at a speed of about Froude number 3.0. Although the aft hull lift enhancement appendages result in a higher resistance cost in the high-speed region, the longitudinal stability is effectively promoted and the occurrence speed of porpoising results in a delay of 1 to 2 m/s.

Stability Analysis of the Ultra-high-speed Aerodynamically Alleviated Marine Vehicle in Waves

“…In the early research, wind tunnel model test has become the main method to study the stability of the ultra-high-speed aerodynamically alleviated marine vehicle [1,2]. Zou et al studied the effects of displacement and gravity longitudinal layouts on the performance of an aerodynamically alleviated trimaran in calm water by model towing test, and results show that moving the gravity center forward and increasing the mass can improve the longitudinal stability, which results in a higher resistance cost in the high-speed region [3]. Wang carried out the study of the WIG craft experimentally based on the moving wavy ground test, and found that the longitudinal characteristics of the vehicle were affected by the wave height and the wave height change rate [4].…”