The effects of minute vortex generator jet in a turbulent boundary layer with adverse pressure gradient

Abstract

Experimental and numerical analysis of active and passive flow control is an important topic of practical value in the study of turbulent flows. This paper numerically analyzed the effects of an air microjet on an adverse pressure gradient turbulent boundary layer over a flat plane. Experimental data were employed to verify the numerical modeling. Vortex formation and development were then studied by changing the microjet to inflow velocity ratio (VR) and microjet angles. According to the results, the best values of the angles [Formula: see text] and [Formula: see text] for various velocities were found to be 30° and from 60° to 90°, respectively. Moreover, at VRs = 1, 2, and 4, the [Formula: see text] values (the distance at which the complete vortex persisted in the flow) were 0.058, 0.078, and 0.18, respectively. Compared to VR = 1, the vortex strength for VRs = 2 and 4 grew by 3.5 and 6.8 times, respectively. When the microjet was added to the flow, the highest variation in the Reynolds stress along the x-direction from VR = 1–4 was 10%. The corresponding values along the y and z- directions were 15% and 2.7 times, respectively.

Comparison and Modification of Various Turbulence Models for Analysis of Fluid Microjet Injection into the Boundary Layer over a Flat Surface

“…Regarding vast applications in engineering, the problem of microjet injection into a fluid continuum has attracted many researchers [1][2][3][4] using different methods to study the problem. Increased computational power, on the one hand, and costly experimental methods, on the other, has caused numerical methods to be considered valuable analysis tools.…”