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The start-up procedure of wind turbines is one of the most complex operating conditions, which includes the dynamic changes of pitch angle decreasing, rotor speed increasing and generator grid-connected, and implies the complex evolution of attack of angle and aerodynamic load. Besides, the velocity and direction of the inflow have strong unsteadiness in the field, which makes the variation of the angle of attack more complex. To reveal the aerodynamic behaviors of the full-scale wind turbine in the start-up procedure, a field measurement campaign was conduct on a 100 kW wind turbine with blade angle of attack, aerodynamic pressure distribution and operating parameters measured in this paper. Aerodynamic power, lift and drag, angle of attack, lift coefficient and pressure distribution were analyzed. As results, the start-up procedure can be divided into free acceleration stage, fast acceleration stage, tip-speed ratio adjustment stage and normal operation stage. The normal forces of airfoils produce the main power to drive the turbine to accelerate in the acceleration stages. The standard deviation of angle of attack decreases continuously with the increase of rotor speed. The flow around the thick airfoil at the blade inner section presents a three-dimensional stall delay effect, and the effect is weakening with the increase of rotor speed. The results reveal the variation of angle of attack and aerodynamic load during the start-up process of a full-scale wind turbine in the field, and provide valuable field measured data for the validation of aerodynamic model. • AOA and aerodynamic load were measured on a 100-kw wind turbine in the field. • The evolutions of AOA and aerodynamic load in the start-up procedure were revealed. • It provides valuable and detailed field measured data for aerodynamic model validation. [ABSTRACT FROM AUTHOR]

• Two-phase olive-mill waste and cattle manure were anaerobically co-digested. • Start-up and stabilization stages were studied in semicontinuous stirred tank reactor. • Propionic accumulation was the key factor in the methanogenic phase inhibition. • Total period of 140 days was required to start-up and stabilization the process. • During the stable period the methane productivity was 0.34 LCH 4 /L R d at 40-d HRT. In this work, the start-up and stabilization stages of mesophilic anaerobic co-digestion of 2POMW and CM in a semi-continuously fed stirred tank reactor (SSTR) were analyzed. Volatile fatty acids (VFAs) were monitored and used as the main control parameter for the start-up and stabilization stages, as well as to evaluate the potential inhibition episodes. The results showed that accumulation of propionic acid was the key factor in the inhibition of the methanogenic phase, leading to process imbalance. To avoid the problems associated with inhibition by high VFA concentrations, several reinoculations were performed using a suitable inoculum adapted to VFA degradation. The start-up phase was carried out in batch conditions for 97 days, reaching a final concentration of propionic acid of 12.77 mg/L. From that moment, the reactor was fed in a semi-continuous mode with a hydraulic retention time (HRT) of 40 days. A total period of 140 days was required to achieve a stable performance of the reactor with a methane productivity of 0.34 LCH 4 /L R d. [ABSTRACT FROM AUTHOR]