Numerical visualization of vortex flow behavior in square jets in cross-flow

Abstract

Direct numerical simulations have been performed in this study to visualize the flow behavior of single and multiple square jets issuing normally into a cross-flow. Three configurations are considered, a single jet located in the centre of the domain, twin jets in side-by-side (SBS) arrangement in the spanwise direction and triple jets in tandem arrangement with twin jets at the front and a third jet in downstream along the centre line. Simulation uses a jet to cross-flow velocity ratio of 2.5 and the Reynolds number 225, based on the free-stream quantities and the jet width. While the vortical structures predicted from single jet case were in good qualitatively agreement with the findings of other researchers, our results show that the process of merging between two counter-rotating vortex pairs (CRVP) in twin jets configurations is strongly dependent on the jet-to-jet edge distance. Further downstream in the far-field, results from the SBS twin jets show a most dominating larger CRVP accompanied with a smaller inner vortex pair. The observations are in good qualitative agreement with the experimental findings in the literature. The resulting flow structures of triple jets in tandem configuration have revealed, for the first time, more complicated flow interactions between individual jets and cross-flow, providing further insights of complex flow physics and its potential engineering applications.

Effect of Jet Inclination Angle and Hole Exit Shape on Vortical Flow Structures in Low-Reynolds Number Jet in Cross-Flow

“…A different flow structure can be noted between the elliptic jet and that of circular and square jets. This is mainly due to the difference in vortex pairing process (see, e.g., Maidi and Yao [15]) which occurs further downstream from the jet orifice. It is important to recall that the presence of vortex pairing and the formation of kidneyand antikidney-shaped vortices depend on the aspect ratio of the elliptic jet [16].…”

Multi-Block High-Order DNS Code Development for Jet in Turbulent Cross-Flow Simulation

“…As an example, DNS of a round turbulent jet in cross-flow by Muppidi and Mahesh [20][21] has shown good agreement with experiments with additional flow quantities, not available from the experiments, being revealed in details. Maidi and Yao [22] also carried out DNS study of multiple square jets interacting with a laminar cross-flow, illustrating complex vortex flow structures. For a jet in a turbulent cross-flow problem, it has been investigated previously by some researchers, experimentally and numerically.…”

Numerical and experimental study of a double jet inclination variation on its dynamic evolution within a crossflow

“…Direct numerical simulations (DNS) of the same single, double and triple jets in crossflow configurations have been performed by Maidi et al [9]. The jet exit section is, however, square and the jets are emitted normally with respect to a jet to cross-flow velocity ratio of 2.5 and a Reynolds number of 225, based on the free-stream quantities and the jet width.…”