The SKOPA Project was divided into 3 technical work packages:
In WP1 (“Hardware design and maturation”), design requirements for each sensor technology (DSHF and FOP) were worked out in cooperation with the project’s topic manager. This enabled the consortium to work with clear boundary conditions within the maturation phase of the sensors and the necessary calibration devices and contributed to reaching the first sub-objective. Furthermore, basic robustness test of both sensor types were performed in hot/cold and humid/dry environment.
In WP2 (“Proof of concept”), preliminary wind-tunnel tests were conducted that helped to improve the sensors for different operating conditions. Specifically, both sensors were tested in both a low-speed and a high-speed wind tunnel at TUB. In the two wind tunnel test campaigns the ability of the FOP sensors to measure static pressure was massively improved. The measured static pressures and pressure fluctuations were validated by Kulite reference pressure sensors. Furthermore, the post-processing routine for the DSHF sensor measurements was optimized during the small-scale wind tunnel tests. Furthermore, it was extended by a procedure to approximate the measurement error of the devices. The results of the shear stress data were compared to empirical formulas from the literature in low-speed testing. In the high-speed testing the flow angle indication of the sensors were evaluated in terms of oil-paint visualization. In both tests the capability of the sensors to measure unsteady flow fields was proved. As an example, the figure “DSHF sensors compared to oil flow visualization.png” compares the direction of the shear stress measured by DSHF sensors and oil-flow visualization in the TUB high-speed wind tunnel. Furthermore the figure “diffusorLS.png” provides results of shear-stress measurements in the TUB low-speed wind tunnel.
In WP3 the two sensor technologies were validated:
- In wind tunnel tests at TU Berlin. Here, an industrially relevant outer wing model with AFC was used to test the response of the sensors (see figure “WP3_WTT.png”). The results indicated that the DSHF sensors were capable of measuring the increased wall shear stress that was generated by the AFC actuators. Furthermore, comparison with reference measurements of the local pressure distribution validated the results of the FOP sensors.
- In flight tests on an ultra-light aircraft. Here, the LASER ultra-light aircraft of TUB was used to validate the flight readiness of both sensor technologies (figure WP3_FT.png”). Specifically, both DSHF and FOP sensors favorably compared to reference measurement in cruise conditions and near separation. As an example, pressure fluctuations obtained on the flap of the flight test aircraft are shown in figure “WP3_FT_pressure.png”.
Within the course of SKOPA, 5 dissemination activities were started:
- Two conference papers were submitted and presented at the Aerospace Europe Conference 2020:
o Kienitz S., Kreft S., Schmid M., Staats M., and Koch A.W. „Miniature Airworthy Fiber-Optic Pressure Sensor for Measuring Static Pressure and Acoustics”, Paper AEC2020_045
o Staats M. and Weiss J. „Measuring Wall Shear Stress in Magnitude and Direction”, Paper AEC2020_122
- One video presenting SKOPA was produced and released on YouTube:
https://www.youtube.com/watch?v=pDV6hyipTac(opens in new window) - Two peer-reviewed journal articles are currently in process
o Kienitz S., Lohr, L., Schmid, M., and Koch, A.W. “ Static and Dynamic Pressure Measurement in Flight Test Application with Optical Fabry-Pérot Sensors”, accepted for publication in IEEE Instrumentation and Measurement.
o Kienitz S., Staats, M., Irsperger, J., Schmid, M., Koch, A.W. Weiss, J. “Fiber Optic Pressure Measurement of Active Flow Control on a Complex Outer Winglet Model”, in preparation.
