Flow around an elastically mounted slender body at high incidence

A numerical study of the flow around an inclined tangent ogive-cylindrical rigid body, mounted on torsion springs and can rotate in the pitching, yawing, and rolling directions, is conducted. The body is subjected to three-dimensional, compressible, laminar flow at Reynolds number of 30,000 based on body diameter and Mach number of 0.2. Second-order implicit scheme is employed for the flow equations, adapted to three-dimensional curvilinear coordinate system, whereas the coupled structural equations, written using Euler angle notation, are solved by an explicit fourthorder Runge-Kutta method. Sub-iteration procedure for the flow-structure coupling is used. The investigation is focused on the influence of the angle of attack, in the range of 20 to 55 degrees, on the elastically mounted slender body fluid-structure interaction. We describe the investigation of two angles of attack: α = 40° andα = 55°. For a fixed body at α = 40° the yaw moment was found to change smoothly with the location of circumferential disturbance, whereas at α = 55° the yaw moment was characterized by almost a square-wave variation behavior with bifurcation points at Φ ~ 90°, Φ ~ 140° and Φ =180°. For an elastically mounted body the response at a = 40° for all disturbance locations resulted in large amplitude periodic yawing and pitching moments. The response at α = 55° resulted in large amplitude moments which occurred only for disturbance locations which coincided with the bifurcation points of the fixed body. The response at the bifurcation points was found to be quasiperiodic for Φ ~ 90°, periodic for Φ ~140° and nonstationary for Φ ~ 180°.