Publication: Numerical and experimental study of passive control in the form of ribs at sonic and supersonic mach numbers
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Date
2023-10-01
Authors
Khan, Ambareen
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Abstract
Flow from Converging and Converging-Diverging nozzles expanded suddenly into the enlarged duct has been investigated experimentally and numerically, with
emphasis on the base pressure, and the development of flow in the duct. In this investigation, the variables considered are the Mach number, Nozzle Pressure Ratio, area ratios, rib geometry, and rib size. Experiments were conducted to control the flow by a semi-circular rib at sonic and supersonic Mach numbers. Results show nozzles flowing under favorable pressure become effective and there is a significant increase in the base pressure. Numerical simulations were done for three area ratios (i.e. 3.61, 5.76, and 7.84) using three shapes of the ribs (i.e. Rectangular, triangular, and semicircular) of three different sizes (i.e. 6 mm, 8 mm, and 10 mm diameter) for four rib locations (i.e. 1D, 2D, 3D, and 4D) at sonic and supersonic Mach numbers. As experimental tests were conducted up to NPR 10 nozzles remained over-expanded for Mach 2.2 and 2.5. To account for design NPR and beyond the numerical simulations were done up to NPR = 25. As a first step CFD results were validated with the experimental results for semi-circular ribs. Among the three shapes of the ribs rectangular ribs seem to be the best option and result in a maximum increase in the base pressure. While scanning the wall pressure in the duct, the flow field is not aggravated due to the presence of various ribs, and the flow field with and without control remains the same.