Improvement of wind turbine aerodynamic performance by vanquishing stall with active multi air jet blowing

Highlights: • Jet blowing improves the output power of HAWTs re-energizing the boundary layer. • Jets at the blade outboard part have greater impact than the inboard and mid parts. • An average 6%–14.5% recover of energy wasted was observed, T1 jet recovers 132%. • Some cases having non-flat surfaces (near leading edge and root) decrease torque. • Synergy of jets, placed one behind the other enhance the acquired more torque. The effects of jet blowing on blade suction side of NREL phase VI horizontal axis wind turbine (HAWT) for alleviation of degraded flow due to boundary layer separation were investigated. A 3D innovative multi-jet blade is simulated using FLUENT 18.2 software applying SST k-ω turbulence model. The spanwise blade portions for jets are outer, middle and inner. Furthermore, twelve jets with 0.04 local chord width have deployed in four chordwise locations of x/c = 0.1, x/c = 0.3, x/c = 0.5 and x/c = 0.7. The torque is sensitive to some dimensionless parameters such as Tip Speed Ratio (TSR) and jet velocity ratio (VR). At the best condition, torque increases about two times with respect to baseline blade. The jet velocity ratios are 1.2, 2.0, 2.4, 2.8, and 3.2. Applying changes in jet parameters, the flow pattern and quality improved. Also, the aerodynamic torque synergy of combinations of two, three and four jets were compared with that of a single jet and the direct relationship between the number of activated jets and the increase in torque was proved. The results showed that jets in blade outer part, have more effects in aerodynamic performance of rotor than the other blade portions. T1 jet produced the highest increase in torque.