Calculation of symmetric vortex separation affecting subsonic bodiesat high incidence

Abstract

A method for calculating the longitudinal aerodynamic coefficients and the pressure distributions on a body at reasonably high angles of attack is presented. The body is represented by a combination of source elements and vortex-lattice elements, including separation of the vortices at increasing angles of attack. The method is selfconsistent in that the body and the separated vortex wake are treated as an integrated interacting system. The location of the separation line can be included as an arbitrary input from experimental data or can be evaluated approximately by a pressure-dependent criterion. Calculated values of the aerodynamic coefficients and pressure distributions on cone-cylinder and ogive-cylinder bodies compare well, qualitatively and quantitatively, with experimental data, including simulation of the dependence on Reynolds number.body length M =Mach number n -iteration number n = vector normal to surf ace N c = axial number of elemental panels for a part of the body N s = circumferential number of elemental panels over half a body Re d = Reynolds number based on diameter S 0 = potential sources strength vector U = freestream velocity u, v y w = velocity disturbance Cartesian components v (x) = variable part of influence coefficient matrix •x,y,z = Cartesian coordinates x = potential vortices strength vector [Eq. (2)] a = angle of attack Ax = integration step size e = difference vector 6 = circumferential angle p s = spectral radius of a matrix II II = norm of a matrix Subscripts 0 = ata = 0deg NOR = normal ref = reference max = maximum N =nose s = separation oo = of the freestream

Calculation of nonlinear subsonic characteristics of wings with thickness and camber at high incidence

“…35 These computation methods can be combined to enable the calculation of the aerodynamic characteristics of wing-body configurations up to relatively high angles of attack.…”

Vortical wakes over a prolate spheroid

“…However, they modeled the separated vortex sheets by only four vortex lines on each side emanating from very narrow segments, aligned again with generators of the body. More recently, a refined version of this method, which relaxed a few Presented as Paper 83-0419 at the AIAA 22nd Aerospace Sciences Meeting, Reno, NV, Jan. [9][10][11][12]1984 of the constraining assumptions but still required the specification of the line of separation, appeared in Ref. 10.…”