Flow separation over highly curved compressor blades can lead to total pressure loss, which adversely impacts the overall efficiency of the compressor. One promising method to reduce this loss is the use of plasma actuators to re-energize the boundary layer flow and delay the separation point. The Single Dielectric Barrier Discharge (SDBD) plasma actuator is particularly favored due to its light weight, ease of installation and rapid response time. Despite its widespread use, the application of SDBD plasma actuator for flow separation control has not been extensively explored in a comprehensive manner. To fill in this research gap, the present study employs numerical simulations to systematically investigate the influence of actuator placement and actuation strength on the boundary layer separation control, with the objective of minimizing total pressure loss. In addition to parametric analysis, the study also delves into the fundamental physics underlying plasma flow control by examining the interactions between the plasma induced wall jet and the separation bubble. The contributions of this paper are twofold. First, for each chord Reynolds number, velocity contours, total pressure loss and efficacy are plotted under different plasma actuation signals. The optimum plasma actuation signal for each chord Reynolds number is identified as the one that achieves maximum efficacy. Second, a detailed analysis is performed using the velocity contours, the displacement thickness and the momentum thickness, offering a deeper understanding of the fundamental physics underlying plasma actuation control.

The effects of tuned surface wettability on oil film formation in a hydrodynamically lubricated contact with a limited lubricant supply (LLS) were explored in this study. Using a slider-on-disc lubricating film test rig, the oil film thickness was measured for three surface wettability configurations: the original disc surface and original slider side surface (OD & OS), the anti-fingerprint (AF)-coated disc surface and original slider side surface (AFD & OS), and the AF-coated disc surface and the AF-coated slider side surface (AFD & AFS). The results indicate that the AFD & AFS combination maintains the largest oil film thickness. This enhanced performance is due to the oil’s nonwetting behavior on the AFD & AFS surfaces, particularly the discontinuous oil droplet/strip by dewetting, which promotes more lubricant supply at the slider inlet. Moreover, the oil accumulates at the inlet in the form of a convex reservoir so that positive Laplace pressure is generated, which effectively bears part of the load, and the film thickness increases.