Vortex breakdown above a delta wing with sharp leading edge

Application Challenge AC1-09 © copyright ERCOFTAC 2024

Description of Experiment

The experiment of TU München is described in detail by Furman and Breitsamter (2009). It has been performed in a low-speed wind tunnel of closed-return type with an open test section. The following measurement techniques have been used for the considered conditions: \begin{itemize} \item Steady surface pressure taps (sampling rate of 100 Hz, averaging time of 10 s). \item Unsteady surface pressure sensors (sampling rate of 2000 Hz, sample time of 40 s). \item Stereo Particle Image Velocimetry (Stereo-PIV) to measure time-averaged velocities. \item Hot-Wire Anemometry (HWA) to measure velocity fluctuations. \item Oil-flow visualization of the surface streamlines. \end{itemize}

Boundary Data

The free stream is defined by the Mach number and angle of attack as specified above. The experimenters give the following indications for the uncertainty in the free stream: \begin{itemize} \item uncertainty in free stream direction less than $0.2^\circ$, \item static pressure variations along tunnel axis less than 0.4\%, \item uncertainty in temporal and spatial mean velocity distribution less than 0.6\%. \end{itemize} Furthermore, the free stream turbulence intensity is stated to be less than 0.4\%.

Measurement Errors

For the different measurement techniques employed (pressures sensors, HWA, stereo-PIV) no information on measurement uncertainties is given by the experimenters.

Measured Data

The measured data consists of the following set: \begin{itemize} \item Steady surface pressure measurements at five chord stations:\\ $x/c_r = 0.2$, $0.4$, $0.6$, $0.8$, and $0.95$. \item Unsteady surface pressure measurements at four chord stations:\\ $x/c_r = 0.4$, $0.6$, $0.8$, and $0.95$. \item Mean velocity field at five cross planes:\\ $x/c_r = 0.2$, $0.4$, $0.6$, $0.8$, and $0.95$. \item Fluctuating velocity field at three cross planes:\\ $x/c_r = 0.4$, $0.6$, and $0.8$. \end{itemize}