A shielded hot-wire probe has been developed which permits the determination of mean velocities, rms velocities, and other turbulence parameters in highly turbulent flow fields and in rapidly reversing flows. The instantaneous velocity vector in the flow field may point in any direction. The shield is a small disk with a hole in its center. Two wires are placed close and parallel to each other inside the hole and normal to the axis of the hole. The effect of the thermal wake of the upstream wire on the downstream wire is used to determine the flow direction instantaneously. Only the thermally undisturbed upstream signals pass through the gate of an amplifier and are further processed. The sign of one of the signals is inverted by the amplifier. The probe has been tested in air flow in the velocity range from 0.3 m/sec to 1 0.0 m/sec. This corresponds to Reynolds numbers based on the shield outside diameter from 7.4 X 102 to 2.5 X 104.

SummaryFor plane turbulent jets and wall jets in uniform streaming flow a simple method, based on a simple empirical formula for the rate of growth which differs from that proposed by Abramovich, is presented. The predictions of length scale, l0, and velocity scale, u0, are in good agreement with experimental results for all ratios of free-stream to jet exit velocity and the eddy viscosity Reynolds number has the correct asymptotic values.

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.

Jayashree Dubeyhas several years of academic experience in the areas of marketing management, production management and quantitative techniques. She has written a number of research papers and theoretical articles. Her areas of special interest are sales promotion, advertising, quality management and portfolio management. AbstractHeavy competition in India in almost all product categories, due to diversification by large and medium companies and increased entry of multinationals, has restricted the growth of domestic companies. Previously, large companies enjoyed high profit margins by targeting premium priced products in the upper strata of Indian society. High levels of competition from equally reputed brands have not only decreased the companies' market share but also created price wars, reducing profit margins and limiting market growth. This has motivated companies to consider the lower classes and the rural segments, which they had previously ignored. By targeting these segments with products in small packs at lower price points, companies have experienced great success. At the same time, small packs also pose some challenges for the companies. This paper explains the importance of small packs for market expansion in various product categories within the Indian market, drawing on several examples to support the views of the authors.

Examination of existing literature is revealing in that although many investigations have been carried out for a plane mixing layer, only a few present turbulence measurements. It is well-known that both mean velocity and turbulence structure in a plane mixing layer are self-preserving, however there appears to be some variations in these measurements. This investigation presents new data on the mean velocity and the turbulence properties of a plane mixing layer. The turbulence measurements differ by about 25% from those obtained by previous investigators and this is attributed to differences in the experimental set up (i.e., presence or absence of a solid wall in the plane x = 0) and errors associated with hot-wire probes (i.e., longitudinal cooling and thermal wake interference). To avoid difficulties experienced by previous investigators in calculating shear stress distribution from a measured nondimensional mean velocity profile a new method is suggested and this provides good agreement between the calculated and the measured shear stress distribution.