Accession Number : ADA188534

Title :   A Discretization of the Integral Equation for the Time Dependent Linearized Subsonic Potential Flow Over a Wing.

Descriptive Note : Interim rept. May 86-Jun 87,

Corporate Author : DAYTON UNIV OH RESEARCH INST

Personal Author(s) : Guderley, Karl G

PDF Url : ADA188534

Report Date : Aug 1987

Pagination or Media Count : 137

Abstract : In a previous report the integral equation for linearized time dependent subsonic potential flow over a wing has been derived. The report describes how this formulation can be discretized. The wing and the wake are divided into triangles. The flow is described by the time dependent potential at the corners of the triangles; in other words the program generates for each corner a table of the potential versus time. The interpolations necessary for the integrations between the corners points and also with respect to time, are described in detail. Initially the upwash is assumed to be known as a function of time over the planform. In practice one will express the upwash by a rather limited number of standard functions defined over the planform multiplied by a superposition of step functions in time. Then it suffices to determine for each of the spatial standard functions the response to a step function in time. In this form the method can be used in aeroelastic problems where the time dependence of the deformations is not always known in advance. In such problems overall forces and momenta rather than the detailed pressure distributions are needed. This is discussed in some detail. After the initial response to a step function the flowfield is rather smooth (although still time dependent). Therefore it can be described by a reduced number of parameters and one can proceed in greater time steps. The procedure by which this can be done is also described.

Descriptors :   *FINITE ELEMENT ANALYSIS, *POTENTIAL FLOW, *WINGS, AEROELASTICITY, DEFORMATION, FLOW FIELDS, INTEGRAL EQUATIONS, PARAMETERS, PLANFORM, PRESSURE DISTRIBUTION, REDUCTION, SPATIAL DISTRIBUTION, TABLES(DATA), TIME, TIME DEPENDENCE, SUBSONIC FLOW, TRIANGLES

Subject Categories : Aerodynamics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE