Parametric Analysis of Turbulent Wall Jets

Abstract

SummaryThe concept of a fully-developed flow based on the hypothesis of selective memory is here applied to general wall-jet type flows. In the presence of a (constant) external stream, the free-stream velocity and the jet momentum flux are taken to be the chief quantities governing the development of the wall jet: two additional non-dimensional parameters, representing a momentum flux Reynolds number and the relative momentum defect in the initial boundary layer, are shown to have only a secondary effect on the fully-developed flow. The standard correlations so determined are also found to predict quite well the flow development in Gartshore and Newman’s experiments on wall jets in adverse pressure gradients; possible reasons for this somewhat surprising result are discussed. Finally it is shown, by application to the still-air case, that the parameters discovered in incompressible flow are, with appropriate but straightforward modification, successful in describing compressible wall jets also.

Submerged wall jet on a macro-rough boundary: turbulent flow characteristics and their scaling laws

“…Additionally, George et al [26] developed the wall-jet similarity theory, which offered a framework to explain the behavior of a wall jet based on their inherent similarities. Importantly, together these studies [25,26] reinforced the scaling proposition of Narasimha et al [22]. Tachie et al [27,28] analyzed the wall jets on smooth and rough boundaries by using both the conventional and momentum-viscosity scaling laws.…”

“…Subsequently several researchers studied the characteristics of time-averaged velocity and turbulence parameters in plane turbulent wall jets [19][20][21]. Traditionally, conventional variables, namely jet velocity (peak velocity in a velocity distribution along the vertical) and jet half-width, are used as velocity and length scales, but Narasimha et al [22] proposed the momentum-viscosity scaling law in a wall jet. Wu and Rajaratnam [23] examined the circular turbulent wall jet on a rough boundary and commented that the velocity distributions along vertical are similar in both the streamwise and spanwise directions.…”

Understanding the Impact of a Serrated Trailing Edge on the Unsteady Hydrodynamic Field

“…The data was calibrated and collapsed well using and 1/2 , which can be seen in reference [37]. The power law relations for wall jet velocity profiles proposed by Narasimha et al [42] and developed by Wygnanski et al [43] are as follows:…”

Parametric analysis of turbulent wall jets in still air

“…the distance between the side walls confining the flow. If this were so, dimensional analysis shows that R om must be a function of (MjLf^lv, so must (equivalently) be the parameter Figure 8 shows, in the variables suggested, the relevant data' 12 -15 - 16 ' which are clearly consistent among themselves; over more than a decade in (M } L) 1/2 /v, the parameter (U<$i)ml(M j L) 1 l' i is practically constant. This implies that the anomalous behaviour observed is due to a threedimensionality, possibly involving secondary flows, in which viscosity plays little role.…”

“…We have therefore examined, from this point of view, all the data available to us on incompressible (nominally) plane wall jets in still air, supplementing these when necessary with some additional measurements 115 ' 16 '. Table I lists the sources of the data, together with some relevant parameters characterising the experimental conditions and a code we shall adopt for referring briefly to each experiment.…”