Inflow and pressure measurements on a full scale turbine with a pressure belt and a five hole pitot tube

We present an autonomous add-on measurement system for detailed aerodynamic measurements on full scale turbines. From the measured data we can derive the local aerodynamic coefficients for the blade section and e.g. compare with wind tunnel data for a similar section. This forms the basis for evaluating how well the airfoil performs on a rotor in the turbulent inflow and rotating environment. We describe the measurement system which comprises a pressure belt with 15 taps, a flyboard with the data acquisition system and a five hole pitot tube measuring the local inflow to the blade section. The system was used on a SWT-4.3-120 DD turbine in a short campaign in June 2021. A trailing edge flap system is installed on that turbine and a particular objective with the measurements was to evaluate the static and dynamic performance of the flap system. The aerodynamic measurements were correlated with the SCADA and flap actuation data. Overall the measurement system performed well and provided good data like smooth pressure distributions. The derived flap performance in the form of the delta lift coefficient was close to what has been measured in wind tunnel tests. Finally, the aerodynamic and aeroelastic dynamic time response of the flap actuation could be characterized with good precision.