Experimental determination of the free-stream disturbance field in a short-duration supersonic wind tunnel

Numerical study of acoustic radiation due to a supersonic turbulent boundary layer

“…The dominance of the acoustic mode over the other two modes confirms that a purely acoustic field in the free stream is successfully isolated by the present DNS. In typical high-speed (noisy) wind tunnels, however, free-stream disturbances may originate from multiple disturbance sources (screens, heat exchangers, valves, bends, diffusers and compressors upstream of the test section, and vibration, roughness and waviness, boundary layer transition and model-wall interference within the test section) and, while acoustic disturbances may still be dominant, all three modes contribute to the free-stream fluctuations in general (Morkovin 1957;Donaldson & Coulter 1995;Weiss et al 2003;Masutti et al 2012). In that regard, the present simulation provides a more controlled setting for studying the spectral features and production mechanisms specific to the acoustic disturbance environment resulting from turbulent tunnel wall boundary layers.…”

“…Modal analysis has been used by a number of experimental researchers to characterize the free-stream disturbance environment in their facilities. Examples include Donaldson & Coulter (1995), who evaluated the level and the sources of disturbances in the Arnold Engineering Development Center (AEDC) tunnels A and B, Weiss, Knauss & Wagner (2003), who used a specially designed constant-temperature anemometer to map out the free-stream disturbance field within a Mach 2.54 short-duration supersonic facility at Stuttgart University, and Masutti et al (2012), who characterized the free-stream fluctuations in the Mach 6 Hypersonic Wind Tunnel H3 of the von Kármán Institute. Table 4 lists the free stream values of several fluctuating flow variables.…”

Constant-Temperature and Constant-Voltage Anemometer Use in a Mach 2.5 Flow.

“…This software correction procedure was developed to provide for large-bandwidth measurements with CTA in a short-duration supersonic wind tunnel. 9 The correction procedure can be written in the frequency domain:…”

Effect of bridge imbalance on the estimation of sensitivity coefficients for constant-temperature hot-wire anemometers

“…where K is the dc amplification of the feedback amplifier. A similar equation for anemometers with variable offset current is available in Weiss (2002).…”

“…In this paper, we investigate the influence of the nonideal behaviour of a CTA upon the determination of sensitivity coefficients obtained when using a standard calibration procedure. This work was originally motivated by the use of a CTA to measure the free-stream turbulence field in a supersonic wind tunnel, where both mass flow and small total temperature fluctuations were present (Weiss 2002, Weiss et al 2003. However, for the sake of simplicity, the present analysis is restricted to incompressible flows where the fluid velocity and temperature are allowed to vary, but an extension to compressible flows where the mass flow and total temperature are variables is straightforward.…”