Grooved Cavity as a Passive Controller behind Backward Facing Step

Sher Afghan Khan; Abdulrahman  Abdulla AlRobaian; Mohammed  Asadullah; Abdul  Mohsin Khan

Authors

Sher Afghan Khan Mechanical Engineering Department, Faculty of Engineering, International Islamic University Malaysia, Kuala Lumpur, Malaysia
Abdulrahman Abdulla AlRobaian Mechanical Engineering Department, Qassim University, Buraidah, Saudi Arabia
Mohammed Asadullah Mechanical Engineering Department, Research Scholar, International Islamic University Malaysia, Kuala Lumpur, Malaysia
Abdul Mohsin Khan Bearys Institute of Technology, Mangalore, India

Keywords:

Grooved cavity , base pressure , wall pressure , Mach number

Abstract

A semicircular grooved cavity is designed for controlling the base pressure and hence the base drag in case of a backward facing step. This paper presents the effect of the continuous grooved cavity to control the base pressure for various compressible subsonic flow to minimize the base drag. Grooved cavity of 1.5 mm radius at 45o along pitch circular diameter of 23 mm in the base region is employed as passive controller. The test is conducted for Mach 0.6, 0.7, 0.8 and 0.9.The square nozzle of side 10 mm with an angle of incidence as 150 on all four side from which the flow suddenly expands to a square duct of side 25 mm acts as backward facing step model. The experimental investigation is carried out for three ducts of length equivalent to 4, 6 and 8 times width. The results of this investigation provide grooved cavity at 45o as a very effective passive control mechanism to regulate the base flows, further at higher Mach numbers it may be associated with minor effect on themain flow field.