Steady and unsteady pressure measurements on a swept-wing aircraft

Abstract

Steady and unsteady pressure measurements are conducted for a tailless aircraft model. The main aim with the presented experimental work is to investigate the difficulties and possibilities involved in using an available pressure sensing system for accurate unsteady pressure measurement. The experimental procedure which is utilised for unsteady pressure measurements is described in detail. In particular, the importance of synchronised timing is recognised. For a harmonically varying pressure a small time delay in the measurement chain can result in a significant phase shift. Also, difficulties and uncertainties that are still present are pointed out. The results from these experiments are compared to numerical results based on unsteady potential flow theory. In general, the experimental and computational results show similar trends. Especially good agreement is found for the steady pressure measurements. For the unsteady pressure measurements a possible Reynolds number dependency is found for the considered test conditions.

Status of the KTH-NASA Wind-Tunnel Test for Acquisition of Transonic Nonlinear Aeroelastic Data

“…An early approach for installing pressure taps was based on a particular design and construction technique developed in a previous project [17,18] at KTH. This technique involves using thin stainless steel tubes mounted flush to the inside of the wing skin.…”

“…The use of electronic pressure scanners for unsteady testing, considering phase shifts and time delays, is discussed and analyzed in detail in the references [17,18]. There are still uncertainties in the relative timing of the measurements.…”

Design and construction of aeroelastic wind tunnel models

“…4. A particular design and construction technique developed in a previous project (8,9) is used. The technique involves using a thin stainless steel tube which is mounted flush to the inside of the wing skin.…”

“…The locations are chosen to be in the middle between the inner and outer pylon and in the middle between the outer pylon and the wing tip. The use of the electronic pressure scanners for unsteady testing, considering phase shifts and time delays, is discussed and analyzed in detail in Refs 8,9. There are still unsolved uncertainties in the timing for this system, hence it is planned to use the scanners in combination with an additional piezo-resistive pressure sensor. Such a sensor typically has better accuracy in phase, and can be used to correct the phase of the scanner pressures as performed in the work by Hübner, Bergman and Löser (11) .…”