Spectral and Statistical Evaluation of Reconstructed Pressure Scanner Measurements for Unsteady Aerodynamic Applications

Hindering the use of pressure scanners for unsteady measurements is the connecting tubing that inherently introduces time lags and pneumatic distortion to the pressure signal received at the sensing element inside the pressure scanner. The character of the distortion varies and can be due to attenuation or resonant amplification. The exact behavior depends on the geometry of the tubing, as well as the environmental conditions. However, the Wiener-filtered inverse system response model (WF-iSRM) developed by Whitmore has been proven effective in reconstructing complex unsteady pressure signals in various low-speed wind tunnel testing applications.

This work evaluates the efficacy of the reconstructed pressure signals from statistical and spectral viewpoints. A test cell has been designed and fabricated to allow for simultaneous and side-by-side measurement of surface pressure in a small cavity using multiple pressure taps and high-speed reference transducers. Pressure measurements from six different tap/tubing geometries are compared against a high-speed reference transducer. In addition to temporal comparisons, power spectral density function, correlation coefficients, magnitude-squared coherence and other statistical parameters are used to demonstrate the effectiveness of WF-iSRM technique in recovering the unsteady pressure signal content. Furthermore, the uncertainty in the reconstructed pressure signals is also presented for the time-domain signals. The results demonstrate the feasibility of using pressure scanning systems for time-resolved pressure measurements in a wide range of aerodynamic applications.