Flutter analysis of a two-dimensional airfoil containing structural nonlinearities

Nonlinear flutter of a two-dimensional airfoil undergoing plunging and pitching motions is studied using a time marching finite difference scheme. The structural nonlinearity considered is of the type due to a spring with preload and freeplay. Flutter is determined from solutions of the structural dynamic equations of motion when either...

Forced oscillation of a two-dimensional airfoil with nonlinear aerodynamic loads

Subsonic wall interference corrections for half-model tests using sparse wall pressure data

A method is described for correcting subsonic wind tunnel measurements on halfmodels in ventilated test sections, operated at subcritical flow conditions at the walls. For perforated walls, the boundary values of the streamwise component of the wall interference velocity are obtained from static pressures measured by a few longitudinal pressure...

A study of transonic flutter of a two-dimensional airfoil using the U-g and p-k methods

An experimental study of the transonic equivalence rule with lift: Part II

The experimental study of the transonic equivalence rule with lift, previously reported in Reference 1, has been extended to include a configuration of swept-back wing-body and the corresponding equivalent bodies for lift and zero-lift. For zero lift, the wing-body is shown to have higher wave drag than that of the equivalent body. At lifting...

Aeroelastic response of an aircraft wing to random loads

A method for the prediction of the response of an elastic wing to random loads at flight conditions using rigid model wind tunnel pressure fluctuation measurements is presented. The wing is divided into panels or elements, and the load is computed from measured pressure fluctuations at the centre of each panel. A series representation with terms...

An experimental study of the transonic equivalence rule with lift

The transonic equivalence rule with lift has been studied experimentally. Under the conditions defined by the rule, wing-body models with the same cross-sectional area distribution but with wings of different aspect ratios and thicknesses were tested at transonic speeds. The correlations of the lift depending wave drag and the lift parameter for...

A method for the prediction of wing response to non-stationary buffet loads

A method for the prediction of the response of a wing to nonstationary buffet loads is presented. The time history of the applied load is segmented into a number of time intervals. In each time segment, the nonstationary load is represented by the product of a deterministic shaping function and a statistically stationary random function. An...

A comparison of methods for calibration and use of multi-component strain gauge wind tunnel balances

A method is presented for calibration of strain-gauge balances which does not require that the components can be loaded independently. Applicable to both 'internal' and 'extemal' types of balance, the procedure uses a single varying calibration load to determine all linear and non-linear calibration coefficients. Constant 'secondary' loads on...

Application of the method of lines to the solution of elliptic partial differential equations

The method of lines is used in this report for solving one linear, two nonlinear elliptic boundary value problems and a linear eigenvalue problem. An analysis of the stability and convergence is made in the linear cases.

A perbutation theory of two-dimensional transonic wind tunnel wall interference

The wind tunnel wall interference in transonic speed is formulated as a perturbation to the basic flow around the airfoil in free air. The perturbation equation is derived from the transonic small disturbance equation and is linear but with variabie coefficients containing the non-linear solution of the basic flow. The equation is solved...

Theoretical analysis of the tyransient response of a wing to non-stationary buffets load

A method for predicting the response of a wing to non-stationary buffet loads is presented. The wing is treated as a cantilever beam with known mass distribution. Using generalized co-ordinates, the vibration of the wing is governed by the second order mass-spring-damper oscillator equation. The buffet load on the wing is expressed as an...

Calculation of the potential flow past multi-component airfoils using a vortex panel method in the complex plane

An efficient algorithm for a vortex panel method in the complex plane is developed to compute the potential flow past multi-component airfoils in free air and a porous-wall wind tunnel. The theoretical foundations of the method - the properties of the source and vortex density functions, the relationship between the exterior and interior flows,...

Analysis of wall interference effects on ONERA calibration models in the NAE 5-ft.x5-ft. wind tunnel

The measurements on three geometrically similar aircraft models by ONERA are used to analyse lift interference effects in the solid and perforated wall test sections of the NAE 5-ft. X 5-ft. test facility. The prediction of the angle of attack correction for both test sections is based on the representation of the model by lifting lines and the...

Three-dimensional swept shock/turbulent boundary-layer separations with control by air injection

Experimentally determined wall pressure distributions, local surface shear stresses and their directions, and detailed turbulent boundary-layer traverses in near zero heat transfer conditions, are presented through skewed shock/boundary-Iayer interaction regions generated by a wedge standing normal to a test wall. The mainstreamMach numbers were...

Controlled and uncontrolled flow separation in three dimensions

The advantages of swept, sharp edges that generate controlled (or fixed) three-dimensional flow separations on a vehicle - because of the qualitatively unchanging flowfield developed throughout the range of flight conditions - are promoted in preferenee to allowing uncontrolled (or unfixed) separations. The three-dimensional viscous flowfields...