In this study, a micro-viscometer is developed for measuring shear-varying blood viscosity over a wide-ranging shear rate. The micro-viscometer consists of 10 microfluidic channel arrays, each of which has a different micro-channel width. The proposed design enables the retrieval of 10 different shear rates from a single flow rate, thereby enabling the measurement of shear-varying blood viscosity with a fixed flow rate condition. For this purpose, an optimal design that guarantees accurate viscosity measurement is selected from a parametric study. The functionality of the micro-viscometer is verified by both numerical and experimental studies. The proposed micro-viscometer shows 6.8% (numerical) and 5.3% (experimental) in relative error when compared to the result from a standard rotational viscometer. Moreover, a reliability test is performed by repeated measurement (N = 7), and the result shows 2.69 ± 2.19% for the mean relative error. Accurate viscosity measurements are performed on blood samples with variations in the hematocrit (35%, 45%, and 55%), which significantly influences blood viscosity. Since the blood viscosity correlated with various physical parameters of the blood, the micro-viscometer is anticipated to be a significant advancement for realization of blood on a chip.

An investigation on the dynamic-stall-suppression capabilities of combustion-powered actuation applied to a tabbed VR-12 airfoil is presented. In the first section, the results from the computational fluid dynamics simulations carried out at Mach numbers of 0.3 and 0.4 are presented. Several geometric parameters are varied, including the slot chordwise location and angle. Actuation-pulse amplitude, frequency, and timing are also varied. The two-dimensional simulations suggest that cycle-averaged lift increases of approximately 4 and 8% with respect to the baseline airfoil are possible at Mach numbers of 0.4 and 0.3 for deep and near-deep dynamic-stall conditions. In the second section, the static-stall results from low-speed wind-tunnel experiments are presented. The low-speed experiments and high-speed computational fluid dynamics suggest that slots oriented tangential to the airfoil surface produce stronger benefits than slots oriented normal to the chord line. The low-speed experiments confirm that chordwise slot locations suitable for Mach 0.3–0.4 stall suppression (based on computational fluid dynamics) will also be effective at lower Mach numbers.