Control of suddenly expanded flow with cavity at sonic Mach number

• Main Authors: Fiqri, Muhammad Ikhwan, Ahmed Pathan, Khizer, Khan, Sher Afghan
• Other Authors: Siddiqui, Altamush
• Format: Book Chapter
• Language: English; English
• Published: Springer 2024
• Subjects: TL787 Astronautics
• Online Access: http://irep.iium.edu.my/111346/6/49d0aee4-661b-4019-9579-d1f692033d79%20%281%29.pdf; http://irep.iium.edu.my/111346/1/Ikhwan%20Paper.pdf; http://irep.iium.edu.my/111346/; https://link.springer.com/bookseries/11693.

Airflow from a convergent nozzle at sonic Mach number expanded suddenly into a circular duct of larger cross-sectional area, provided with annular rectangular cavities, which was studied numerically, focusing attention on the base pressure, and the flow development in the enlarged duct. It was found that the base pressure is strongly influenced by the expansion level at the nozzle exit, the area ratio of the passage, and the length-to-diameter ratio of the enlarged duct. For the low area ratio, the annular cavities increase the base pressure. Also, the cavity aspect ratio influences the base pressure significantly for the lower area ratio. The nozzle pressure ratio (NPR), the cavity aspect ratio (ASR), and the cavity location (CL) were considered as the flow and geometrical parameters in this study. The computational fluid dynamics approach uses flow from a convergent nozzle for subsonic and sonic Mach numbers with sudden expansion. For this investigation, the Mach number is 1.00, which is sonic, and the duct-to-nozzle exit area ratio is 2.25. The length-to-diameter ratio (L/D) was altered as 1, 2, 3, 4, and 6, while the simulated nozzle pressure ratio (NPR) was 1.5, 2, 3, 4, and 5. The annular rectangular cavities with a width of 3 mm and height of 3 mm for ASR 1. A width of 3 mm and a height of 6 mm for ASR 2 are considered to compare the base pressure results. The nozzle was modeled and analyzed using this work's K-standard wall function turbulence model. The results show that the NPR and cavity placement from the base wall significantly impacted the base pressure.