DBD Plasma Actuation on the Blades of Axial-Flow Turbomachinery

Flow separation, or stall, in axial flow turbomachinery results in a loss of pressure or compression in the case of fans and compressors, or the loss of power or thrust generation in the case of turbines. Wave-power-based Wells turbines, in particular, suffer so acutely from blade stall during normal operation, that it compromises their viability as a major renewable energy resource. In this research, pulsed dielectric barrier discharge (DBD) plasma actuators were implemented on the blades of a mono-plane Wells turbine impeller and its full-bandwidth performance was evaluated. An initial parametric study indicated that blade-tip reduced frequencies ≥2.5 produced the greatest impeller acceleration from rest. The corresponding physical pulsation frequency was then used as a basis for conducting nominally steady-state experiments as well as experiments involving acceleration and deceleration of the impeller. Data so acquired, corresponding to a reduced frequency range of 0.9 to 2.5, was compiled to construct an impeller performance map. Plasma pulsations dramatically increased the effective impeller bandwidth by producing useful net power well beyond flow ratios where mono-plane impellers spin down to a standstill. In fact, the shaft power at a 17° blade-tip angle of attack exceeded the plasma input power by a factor of 33. These findings are potentially game-changing for wave energy generation and axial flow turbomachinery in general.