Accession Number : ADA182459

Title :   Large-Eddy Numerical Simulation of an Array of Three-Dimensional Impinging Jets.

Descriptive Note : Final rept. May 85-Jul 86,

Corporate Author : FLOW RESEARCH CO KENT WA

Personal Author(s) : Rizk,M H ; Menon,S

PDF Url : ADA182459

Report Date : Apr 1987

Pagination or Media Count : 189

Abstract : Numerical simulations of a row of impinging jets are performed. Both the impinging jets and the fountains caused by the collision of the wall jets are modeled in the simulations. The problem considered contains the essential features of twin jets impinging on the ground, simulating the hovering configuration of a VTOL aircraft. The flow is assumed to be governed by the time-dependent, incompressible Navier-Stokes equations. The large-eddy simulation approach is followed in which all scales resolvable by the grid resolution are computed explicitly, while the small-scale turbulence structures, which are nearly universal in character, are modeled by an eddy viscosity formulation that simulates the energy cascade into the small scales. The Navier-Stokes equations are solved using a staggered computational mesh. Central finite differencing is used to discretize all terms except the convective terms, which are discretized using the QUICK scheme. The Adams-Bashforth scheme is used to advance the solution in time. The pressure Poisson equation is used in place of the continuity equation. Efficient direct solutions are obtained for the pressure field, which allows the continuity equation to be satisfied at each time step. This study focuses on the motion and dynamics of large-scale structures that have been experimentally observed in jet flows. The behavior of the jets and the fountain due to introducing axisymmetric, azimuthal and random disturbances at the jet exists is investigated.

Descriptors :   *IMPINGEMENT, *JET FLOW, *SIMULATION, *NUMERICAL METHODS AND PROCEDURES, EFFICIENCY, EQUATIONS, FORMULATIONS, GRIDS, INCOMPRESSIBILITY, MESH, NAVIER STOKES EQUATIONS, NUMERICAL ANALYSIS, POISSON EQUATION, PRESSURE, RESOLUTION, SOLUTIONS(GENERAL), THREE DIMENSIONAL FLOW, VERTICAL TAKEOFF AIRCRAFT, VISCOSITY, COMPUTATIONS, CONTINUITY, CONVECTION, DYNAMICS

Subject Categories : Aerodynamics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE