Nozzle flow control through D-shape rib with abrupt change in area at Mach one: a comprehensive CFD approach

Newaz, Md. Ashif and Khan, Sher Afghan and Sapardi, Mohd Azan Mohammed and Hoq, S. M. Afzal (2025) Nozzle flow control through D-shape rib with abrupt change in area at Mach one: a comprehensive CFD approach. Kronika Journal, 25 (10). pp. 140-174. ISSN 0023-4923

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Abstract

The development of the enlarged duct appears to be of interest to many practical problems in the automobile industry and aerospace vehicles, such as unguided rockets, missiles, and the space shuttle. The study of space shuttles and high-performance military aircraft has made the investigation of turbulent flow in separated regions a vital topic. Researchers are also interested in turbulent flow in transonic and supersonic flow. There is considerable relief for the flow when it separates and expands once the area of the larger duct suddenly increases. There are two areas where the shear layer emerges: the separated flow and the main flow. Considerable drag results from the split stream line becoming reattached to the duct, creating a recirculation zone where the pressure is lower than that of the surrounding air. Flow from a converging nozzle is suddenly exhausted to a larger diameter. The duct diameter is 20 mm. Base pressure management using a D-shaped rib as a passive control mechanism is the primary focus of this study. The passive control was located at various positions, with a length-to-diameter ratio (L/D) of 0.5, 1, 1.5, 2, and 3. Numerical simulations were conducted for 0.5, 1, and 1.5 mm rib radii. Results indicated that the D-shape rib with a 0.5 mm radius is ineffective, except at nozzle pressure ratios of 4 and 5. The maximum increase in the base pressure is attained for a rib radius of 1.5 mm, and a moderate rise is obtained for a 1 mm radius, as this 1 mm height of the rib appears to be ineffective. It is observed that the rib locations at L/D = 2 and 3 are inadequate, as the flow becomes attached to the wall around L/D = 1 to 1.5. Hence, one can select the rib radius and height based on the user's requirements, as the flat surface of the rib faces the shear layer after being exhausted from the nozzle

Item Type:	Article (Journal)
Uncontrolled Keywords:	D-shape Rib, L/D Ratio, Nozzle Pressure Ratio, Mach Number, Expansion Level
Subjects:	T Technology > TL Motor vehicles. Aeronautics. Astronautics > TL500 Aeronautics
Kulliyyahs/Centres/Divisions/Institutes (Can select more than one option. Press CONTROL button):	Kulliyyah of Engineering > Department of Mechanical Engineering
Depositing User:	Prof. Dr. Sher Afghan Khan
Date Deposited:	13 Oct 2025 11:30
Last Modified:	13 Oct 2025 11:30
URI:	http://irep.iium.edu.my/id/eprint/123657

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