Numerical investigation of airfoil/jet/fuselage-undersurface flowfields in ground effect

Abstract

THE Euler/Reynolds-averaged compressible NavierStokes, continuity, and energy equations are solved in conjunction with a two-equation (K-e) turbulence model for two-dimensional flows related to vertical/shor t takeoff and landing (V/STOL) aircraft. Beam and Warming's implicit factored central-difference scheme with/without diagonalization is introduced. For the airfoil/jet/ground-interaction flowfields, the in viscid and laminar flows are considered. Different values of parameters (such as width, velocity, and temperature of jet; height of jet above the ground plane; and freestream Reynolds number) are employed to study the physical phenomena and aerodynamic coefficients. Also presented is information about the turbulent impinging jet with curved fuselageunder surf ace, pressure distributions on the ground plane and fuselage-under surf ace, and distributions of turbulent kinetic energy and velocity component along the center line. Contents The aerodynamic interaction caused by the flow around the airfoil, fuselage-under surf ace, and ground in the presence of lift jets is important in V/STOL aircraft design. Based on the solution of three-dimensi onal thin-layer Navier-Stokes equations, the velocity vectors and suck-down effect of laminar flow around a delta planform wing, equipped with two thrust reverser jets, in ground effect have been studied by Chawla et al.1 To describe the vortex formulation behind the jet and to include the effect of jet/ground interaction on the flowfield around the airfoil, Agarwal and Deese2 modified Jameson's Euler code (FLO-53) for computing almost incompressible flow. Agarwal and Bower3 studied the flow behaviors of the turbulent jet impingement flowfields with curved fuselage-undersurface. The governing equations, including a two-equation model, were expressed in stream function/vorticity forms and formulated by the finite-difference method. In this paper, Beam and Warming's scheme with/without diagonal form4'5 is introduced to solve the Euler/Reynolds-averaged compressible full Navier-Stokes, continuity, and energy equations in conjunction with a two-equation (K-e) turbulence model.6 The air foil/jet/fuselage-under surf ace flowfields in ground effect are investigated. For the air foil/jet/ground-inter action flowfields, the methods of characteristi c, average process, slip/no-slip, and adiabatic-wall conditions are respectively applied to the far-field boundary, trailing edge, wake cut, surface of airfoil, and ground plane. Velocity and temperature about the entering jet