Three-Dimensional Wall Jet Originating from a Circular Orifice

Abstract

SummaryAn incompressible three-dimensional turbulent wall jet originating from a circular orifice located adjacent to a plane wall is studied both theoretically and experimentally. An approximate similarity analysis predicts that the two transverse length scales,l0and L0, and the inverse of the mean velocity scale grow linearly with distance downstream x from the orifice. Experimental measurements of mean velocity and longitudinal turbulence intensity profiles were made both in air and water with hot-wire and hot-film anemometers respectively. The behaviour predicted by the similarity analysis was verified. It was found that the rate of growth of the length scale normal to the plane wall, dl0/dx, was somewhat less than that found for a two-dimensional wall jet, whereas the rate of growth of the length scale in the lateral direction, dL0/dx, was about seven times greater than dl0/dx.

Boundary impingement and attachment of horizontal offset dense jets

“…Subsequently, when the impingement occurs, the upper and lower halfwidths for both concentration and velocity deviate abruptly, and the splitting points are approximately consistent with the previously determined impingement points. Notably, the regressed straight line describing the increase of the velocity half-width with the downstream distance reported in Newman et al (1972) are within the scatter of the present data.…”

“…14, in which the distance from the upper and lower half heights to the centerline, i.e., the half-widths, are plotted against the downstream distance. Also included in the figures are the variation of the velocity half-widths of a non-buoyant jet (Johnston and Volker, 1993) and a three-dimensional wall jet (Newman et al 1972). Prior to the impingement point, the spreading rate for both concentration and velocity are found to be appreciably lower than the non-buoyant jet.…”

“…It should also be noted that offset jets have been widely used in various other industrial applications, such as burners, boilers, gas turbine combustion chambers, and fuel injection systems (Nasr and Lai, 1998). In addition, threedimensional non-buoyant wall jets have been studied extensively in the past, and the relevant results can be used for comparison (Rajaratnam and Subramanya, 1968;Newman et al, 1972;Rajaratnam and Pani, 1974;Law and Herlina, 2002;Herlina and Law, 2002).…”

Confinement Effects in Shallow-Water Jets

“…Although wall jets in quiescent surroundings have been studied extensively both experimentally and theoretically (for instance, a plane wall jet, a radial wall jet, a curved wall jet, and an annular wall jet), there have been relatively few investigations of threedimensional wall jets (Sforza & Herbst 1970, Newman et al 1972, Rajaratnam & Pani 1974, Davis & Winarto 1980, and Launder & Rodi 1983. A three-dimensional wall jet is produced by a round, square, or rectangular nozzle (of finite aspect ratio) or by a nozzle of comparable geometry along a solid wall.…”

“…A three-dimensional round wall jet with the jet orifice affixed parallel to the plane wall (i.e. the distance from the nozzle centreline to the wall is 0.5 nozzle diameters) was studied experimentally and theoretically by Newman et al (1972). It was shown from similarity considerations (neglecting wall friction) that the two half-widths (normal and parallel to the plane wall) and the decay of the mean maximum velocity should grow linearly with distance from the orifice.…”