Research on planing motion and stability of amphibious aircraft in waves based on cartesian grid finite difference method

Abstract

The wave resistance of amphibious aircraft planing in waves is an important consideration in the design of seaplanes. Based on the Cartesian Grid Finite Difference Method (CGFDM), this paper investigates the effect of different wave elements and planing speeds on the motion response and vertical overload of amphibious aircraft, and analyzes the conditions for the occurrence of jump motion and stability of the aircraft. The finite difference method (FDM) based on a fixed regular cartesian grid system is used to solve the flow field, and the Tangent of Hyperbola for Interface Capturing with Slope Weighting (THINC/SW) method is used to capture the violent free surface flow, while the immersed boundary method (IBM) is used to effectively solve the problem of large motion of the object. The numerical simulation results are compared with the experimental values and show good agreement. The calculation results demonstrate that the heave and pitch motion responses of amphibious aircraft show a certain regularity with changing wave conditions. As the speed increases, the vertical overload rises sharply as the aircraft enters the complete planing state, and the slamming effect on the bottom of the aircraft's forward fuselage is most significant. When the wavelength reaches 1.38 to 2.76 times the length of the fuselage, high speeds and large wave steepness are more likely to induce jumping motions and reduce the stability of the aircraft's movement. This study can provide a reference basis for amphibious aircraft to effectively avoid unsafe sea state areas.