Secondary Flow Control Using Vortex Generator Jets

Abstract

In this paper, results are presented of an experimental investigation into the effectiveness of vortex generator jets in controlling secondary flows in two-dimensional S-duct diffusers. The experiments were performed in uniform and distorted inflow conditions and the performance evaluation of the diffuser was carried out in terms of static pressure recovery and quality of the exit flow. In the case with inflow distortion, tapered fin vortex generators were employed in addition to vortex generator jets to control flow separation that was detected on the wall with inflow distortion. Detailed measurements including total pressure, velocity distribution, surface static pressure, skin friction, and boundary layer measurements were taken at a Reynolds number of 7.8×105. These results are presented in terms of static pressure rise, distortion coefficient, and total pressure loss coefficient at the duct exit. For uniform inflow, the use of vortex generator jets resulted in more than a 30 percent decrease in total pressure loss and flow distortion coefficients. In combination with passive device (tapered fin vortex generators), the vortex generator jets reduce total pressure losses by about 25 percent for distorted inflow conditions. A potential application of this method may include control of secondary flows in turbo machinery.

Size-selective separation of micro beads by utilizing secondary flow in a curved rectangular microchannel

“…9 This secondary flow can be found in numerous flow situations such as the blade passage in turbomachinery, a bent pipe, aircraft intakes, diffusers, and heat exchangers. [10][11][12][13][14][15] However, they consider the secondary flow as being the loss of momentum and energy.…”

Active separation control on a very thick wind turbine airfoil - A URANS and DDES perspective

“…Passive vortex generators (VG) are widely used, but fluidic VGs are less often. The studies for fluidic VGs showed that the method has a potential for separation delay, and was confirmed by several authors such as Ball [6], Johnston & Nishi [7] and Sullerey & Pradeep [8]. Combining the jet influence with a boundary layer suction improves the flow stability and, thus, separation can be more effectively delayed.…”

Experimental Studies of Active and Passive Flow Control Techniques Applied in a Twin Air‐Intake

“…It is found from the literatures [17, 18] that the vortex generators attached to the top and bottom walls of the air-intake effectively control the secondary flow instead of using it on side walls. This is evident from Table 2 that secondary flow non-uniformity ( S io ) sometimes increases for the air-intakes with vortex generators attached to its side walls, whereas the same parameter only records a reduction if vortex generators are attached to its top-bottom walls irrespective of its heights.…”