Abstract
In the present experimental investigation, shear sensitive liquid crystals have been successfully used to study the flow characteristics and detect separation in two-dimensional Sduct diffusers of different curvatures. Tapered-fin vortex generators in two different orientations were used to control flow separation that was observed on one of the curved walls of the diffuser. The results were verified by conventional oil flow visualization technique and excellent agreement was observed. In addition to visualization, detailed measurements that included wall static pressure, skin friction, diffuser exit total pressure and velocity distributions were taken in a uniform inlet flow with Reynolds number of 3.49 × 105. These results are presented here in terms of skin friction distribution, distortion and total pressure loss coefficients. The extent of the separation zone (in terms of intensity of red distribution) in the diffuser with and without vortex generators (in both configurations) compared well with the Preston tube measurements. The present study demonstrates that shear sensitive liquid crystals can be efficiently used to study the flow physics in complex internal flows. In addition, the results also indicate that shear sensitive liquid crystals can be effectively used not only as flow visualization tool but also to gain quantitative information about the flow field in internal flows.
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A. M. Pradeep: He is currently a Ph.D. candidate in the Department of .Aerospace Engineering, Indian Institute of Technology, Kanpur. He received his M.Tech. in Aerospace Engineering in 2000 from Indian Institute of Technology, Kanpur. His research interests are flow characteristics in curved diffusers, active and passive control of internal flows, and flow visualization.
R. K. Sullerey: He is a Professor in the Department of Aerospace Engineering, Indian Institute of Technology, Kanpur. He received his Ph.D. degree in Aerospace Engineering, Indian Institute of Technology, Kanpur in 1975 and has been a faculty in the department since 1969. His research interests are aerospace propulsion, design and performance of turbomachinery, flow control of internal flows and concept design and analysis of air breathing propulsion systems.
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Pradeep, A.M., Sullerey, R.K. Detection of separation in S-duct diffusers using shear sensitive liquid crystals. J Vis 7, 299–307 (2004). https://doi.org/10.1007/BF03181534
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DOI: https://doi.org/10.1007/BF03181534