Accession Number : ADA305405

Title :   Closed-Loop Control Systems for Unsteady Forebodies and Three-Dimensional Pitching Airfoils at High Reynolds Number.

Descriptive Note : Final rept. Jan 93-Aug 95,

Corporate Author : ILLINOIS INST OF TECH CHICAGO FLUID DYNAMICS RESEARCH CENTER

Personal Author(s) : Williams, David R. ; Acharya, Mukund ; D'Souza, A. F.

PDF Url : ADA305405

Report Date : DEC 1995

Pagination or Media Count : 115

Abstract : Progress made on closed loop control systems with application to aircraft forebodies and pitching airfoils is described in this report. The three main areas of the investigation included: (1) development of suitable control law algorithms for control of pitching wings and forebodies, (2) vorticity control on three-dimensional swept wings at high angles of attack, and (3) vortex control on forebody models at high angles of attack with unsteady motions. The three areas were investigated in parallel by laboratory experiment and numerical simulations. The numerical simulations examined the ability of distributed suction to control the flow over an airfoil undergoing a pitch-up motion and sinusoidal oscillation. Experiments on the feasibility of controlling dynamic stall using leading-edge suction were conducted. By studying the influence of different parameters such as pitch rate, Reynolds number, suction timing, suction slot size and location, a scaling law for the suction flow rate was developed. The third area of. investigation involved closed-loop control of forebody flow vortex asymmetry. By incorporating a closed- loop system, the desired side force could be maintained under a variety of different pitching. The relative performance of linear, nonlinear and neural network control algorithms was explored.

Descriptors :   *FLIGHT CONTROL SYSTEMS, *AERODYNAMIC STABILITY, *AIRFOILS, *CLOSED LOOP SYSTEMS, ALGORITHMS, LABORATORY TESTS, NEURAL NETS, PITCH(MOTION), HIGH RATE, SIZES(DIMENSIONS), DYNAMICS, LOADS(FORCES), NUMERICAL ANALYSIS, RATES, VORTICES, THREE DIMENSIONAL, SWEPT WINGS, STALLING, NONLINEAR SYSTEMS, FLOW RATE, SCALING FACTOR, SLOTS, LEADING EDGES, CONTROL THEORY, PARALLEL ORIENTATION, WINGS, SUCTION, REYNOLDS NUMBER, HIGH ANGLES.

Subject Categories : Aerodynamics
      Flight Control and Instrumentation

Distribution Statement : APPROVED FOR PUBLIC RELEASE