A series of experimental and computational studies was conducted on vane-type microvortex generators (MVG) with the aim of better understanding the behaviour and to improve the design of such devices. The traditional rectangular and triangular vanes along with unique NACA0012 and E423 airfoils shaped vanes were studied with a height of 0.2δ while being embedded in a turbulent boundary layer of a flat plate. To assess the reliability of the numerical prediction of the drag forces acting on a MVG, a wind tunnel experiment was conducted. The experiment was conducted at a Reynolds number of 155, based on the friction velocity and the MVG height. A very good agreement was found between the experimental and numerical drag predictions for the MVGs with strong vortices. Fair agreement was found for the two MVGs with weak vortices. From the four-specified vane-type MVGs, the best performing MVG configuration was sought by looking at the ratio of the vortex's circulation strength to the drag of the MVG vanes. It was found that triangular vanes had the best ratio and NACA0012 shaped vanes had the second best ratio. With altercation of the vane angle, vanes placed at angles of 18˚ to 20˚ had the best ratio. To supplement the performance study, the effect of the Reynolds number on the MVGs was also considered. A rectangular MVG vane was modelled at Reynolds numbers of 90 to 1150. A logarithmic relation was found between the Reynolds number of the MVG and the generated vortex's circulation and the drag of the MVG.
The present study investigates the flow physics on MicroVortex Generators (MVGs) in order to improve their performance in turbulent boundary layers (TBLs). TBLs can be a challenging environment for MVGs because of the streamwise length of the shedded vortex and its increased parasitic drag. Large-Eddy Simulation (LES) is used to properly resolve the turbulent boundary layer of a flat-plate with a zero-pressure gradient and MVG vane. Three different vane-types are investigated (e423-Mod, triangular, and rectangular vanes) in a single vane configuration. Important flow features such as a separation bubble on the leading edge of the rectangular vanes which introduced unsteadiness into the vortex formation and degraded the MVG's efficiency was observed. The e423-Mod and triangular vanes was observed to be more aerodynamically efficient. The triangular vane was found to be the most efficient when evaluated immediately downstream of the vane. However, the vortex from the triangular vane decayed very rapidly due to it being formed very close to the wall which degraded its efficiency further downstream. The e423-Mod vane avoided this problem but its drag was very high relative to the strength of the generated vortex and its vortex experienced a brief period of rapid decay immediately downstream decreasing its efficiency. Further downstream, the vortex of the rectangular vane at 16° became the most efficient through a combination of low vane drag and low vortex decay in the TBL, demonstrating the need to consider a range of issues when designing an MVG.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.