The flow field from a piston-cylinder synthetic jet actuator was investigated in detail over a range of dimensionless stroke values, L∘∕D∘, and Reynolds numbers, ReU∘. In each of the test flows examined, only one of these dimensionless groups was varied. The flow fields were examined using particle image velocimetry measurements in a plane bisecting the jet. A slug flow model was used to determine scaling parameters for the jet flow field. In the near-field of the orifice, the flow was dominated by the vortex ring formed during the expulsion phase of the actuator cycle, and the flow field scaled exclusively on the actuator stroke, L∘. For distances from the orifice greater than L∘, the flow field resembled a conventional, round turbulent jet. The resemblance was not complete as the synthetic jet had a faster spreading rate with a correspondingly more rapid decline in the mean centerline velocity. The dimensionless jet momentum was comparable at the higher stroke values for the same Reynolds numbers, and the jet momentum increased with Reynolds number. It is apparent from this work that the slug flow model provides suitable scaling parameters for the near- and far-field regions of a synthetic jet flow. Moreover, the study conclusively demonstrates that the dimensionless stroke, L∘∕D∘, uniquely identifies a synthetic jet flow.
This paper examines the influence of the structural positions of different demographic groups in the science and engineering labor force on their access to the allocation of favorable work experiences and their effect on decisions about the evaluation of their performance. Our hypotheses challenge assumptions in the management literature that each group will necessarily express ingroup bias and outgroup derogation. Instead, we call attention to the status hierarchy that develops from status construction processes, the prototypicality that emerges from social categorization processes, and a framework of stereotype content that is based on an analysis of structural positions among groups in the society. Using hierarchical linear modeling with survey data from scientists and engineers in research and development in 24 major corporations, we find that U.S.-born white males, who constitute the normative ingroup, receive advantages in both allocation and evaluation decisions from all evaluators, not just from other white men. We also find that normative outgroups (non-male, non-whites, and/or non-U.S. born) receive ambivalent or indifferent more than discriminatory or biased treatment, depending on their structural position in relation to U.S.-born white men, and that these effects are independent of who is doing the rating.
The control of separated flow on an unconventional airfoil using synthetic jet actuators was investigated experimentally. A symmetric airfoil based on the aft portion of a NACA four-digit series airfoil with a cylindrical leading edge was used in the experiment. The tests were conducted at Re c =3(10) 5 . For a>5°, the flow separated from the airfoil surface. Applying synthetic jet control near the leading edge, upstream of the separation point, reattached the separated flow fixangle of attack up to 18°. The effect of control location and amplitude was investigated for different angles of attack. Hot wire measurements in the nearwake of the airfoil revealed a transient passing of vortices associated with the transition from separated to reattached flow on the airfoil.
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