Comparison between measured and calculated stall-flutter behaviour of a one-bladed model rotor

In a low-speed windtunnel flutter tests are performed with a driven model rotor, consisting of one rigid blade hinged at the root by a weak bendingtorsion spring. Many flutter points in non-stalled and stalled flow are measured with three different model configurations by changing the rotor speed at constant tunnel velocity. Aerodynamic...

Theory and experiment in unsteady aerodynamics

In this paper , we will consider, by means of a historical review, the role of theory and experiment in the development of unsteady aerodynamics. It is not our intention to sum up all the important contributions. We will only try to sketch roughly the changing positions of theory and experiment.

The influence of the main flow on the transfer function of tube-transducer systems used for unsteady pressure measurements

An experimental investigation has been performed, which revealed a considerable difference between the dynamic response characteristics of a tube-trauisducer system with the entrance in still air and one having an airflow across the entrance orifice, The differences observed could be explained theoretically by modifyink the existing calculation...

High subsonic and transonic effects on pressure distributions measured for a swept wing with oscillating control surface

An analysis is given of pressure distributions measured on a swept wing model with harmonically oscillating control surface at subsonic to supersonic Mach numbers and at various frequencies. The influence of Mach number and finite span effects is discussed. Some comparisons are made with pressure distributions on a two-dimensional wing and with...

Present status of unsteady aerodynamics for lifting surfaces

A survey is given of existing theoretical and experimental routine methods for determining pressure distributions or generalised forces on oscillating lifting surfaces. Some comparisons between results of theory and experiment are shown. Techniques are indicated to apply measured data in development work. Tunnelwall influence on measurements is...

Binary flutter calculations with theoretical and empirical aerodynamic derivatives for a wing-control surface system in two-dimensional incompressible flow

A number of comparative flutter calculations for a two-dimensional wing-control surface system has been performed to demonstrate the usefulness of empirical formulae for the control surface derivatives. Furthermore attention has been paid to the influence of the chord ratio T on the flutter behaviour and to the sensitivity of the system to each...

Resultaten van drukmetingen aan een drietal verschillende vleugel-roer combinaties in incompressibele stroming

Dit verslag geeft in voorlopige vorm de resultaten van drukmetingen aan een drietal verschillende vleugel-roer combinaties. Naast de gemeten drukverdelingen en de bijbehorende theoretische krommen worden ook verscheidene luchtkrachtcoëfficiënten, verkregen door integratie van de gemeten drukverdelingen, weergegeven. Een interpretatie van de...

Analysis of pressure distributions measured on a wing with oscillating control surface in two-dimensional high subsonic and transonic flow

At this moment little experimental material is available about the instationary aerodynamic forces on wing-control surface combinations in high subsonic and transonic flow. Up to now the investigations on this subject have been restricted mainly to the determination of overall hinge moments by means of free oscillation techniques and to the...

A method for estimating unsteady pressure distributions for arbitrary vibration modes from theory and from measured distributions for one single mode

A method is proposed to estimate for a lifting surface pressure distributions to be measured for arbitrary vibration modes by the aid of theory and measured distributions for one single mode. Its usefulness is demonstrated on hand of two swept wings of small aspect ratio oscillating in incompressible flow. Due to insensitivity to reduced...

Theoretical and experimental results for the dynamic response of pressure measuring systems

For a series-connection of N thin tubes and N volumes a general recursion formula has been derived that relates the sinusoidal pressure disturbance in volume; to the pressure disturbances in the preceding volume j and the next volume j - 1. From this recursion formula the expressions for the complex ratio of the pressure fluctuation of each...

Some aspects of unsteady pressure measurements

Some aspects concerning the accurate experimental determination of unsteady pressures on harmonically oscillating wings are considered. Furthermore a brief description of a special measuring technique is given. Finally various possibilities for the application of measured pressure distributions to flutter calculations are discussed.

A new method for measuring the pressure distribution on harmonically oscillating wings

A method is described, enabling to measure the pressure distribution on oscillating wings with the aid of one pressure transducer, mounted inside a scanning valve. The scanning valve, located outside the testsection, is connected to the model orifices by equal pressure leads. Special measures are taken to simplify the correction procedure,...