A finite element model has been developed to predict the level of entrainment and mixing in a confined turbulent jet of variable density. Turbulence closure has been achieved by a modified Prandtl mixing length model. The scheme is validated for various nonisothermal Craya-Curtet numbers with available experimental data. Results are compared with available analytical solutions for the rate of entrainment, and a reasonable match is observed. The effects of aspect ratio, density ratio, and jet location on entrainment and mixing of ambient fluid are discussed. © 1999, Taylor & Francis Group, LLC. All rights reserved.

T Sundararajan

Department of Mechanical Engineering

U. S.Premananda Shet

Aspect ratio

finite element method

Jets

Mathematical models

Turnaround time

VARIABLE DENSITY CONFINED JETS

Heat transfer

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Entrainment and mixing studies for a variable density confined jet

Numerical Heat Transfer; Part A: Applications

The present work deals with the experimental investigation of entrainment characteristics of confined/semiconfined circular and noncircular jets. The jet fluid, after issuing out of a nozzle of circular or noncircular cross section, enters a circular mixing tube of larger area, and during this process it entrains some ambient fluid into the mixing tube. The flow is incompressible and isothermal at a jet Reynolds number of 7200. The experimental results obtained in the study are first validated with the approximate theoretical analysis of Pritchard et al. (1997) and also with the similarity solution proposed by Becker et al. (1963) for circular nozzles. It is observed that the similarity solution is applicable for circular as well as noncircular jets in the region close to the jet axis and away from the nozzle exit plane. The entrainment ratio increases to a maximum value as the jet location is shifted away from the tube inlet; for the configurations studied, enhancement up to 30% has been observed in the entrainment ratio with shift in jet location. For a smaller mixing tube diameter and jet located at the inlet of the mixing tube, the circular jet entrains more than noncircular jets. For a larger mixing tube or shifted jet locations, the noncircular jets entrain more of ambient fluid, in general. Among the different noncircular geometries considered, the jet having the cross section of an isosceles triangle causes maximum entrainment.

Journal of Fluids Engineering, Transactions of the ASME

Mixing and Entrainment Characteristics of Circular and Noncircular Confined Jets

The double-diffusive natural convective flow within a rectangular enclosure has been studied using a generalized porous medium approach. The results have been validated with the help of theoretical heat transfer results available for various porous medium flow models and also with the experimental results for double-diffusive convection in a fluid-filled rectangular cavity. The present generalized model covers the entire range from Darcy flow to free fluid flow. Numerical predictions by the model indicate that the flow pattern as well as the heat and mass transfer are profoundly influenced by the buoyancy ratio. Also non-Darcy effects on flow, heat, and mass transfer become significant when the Rayleigh or Darcy numbers are large. The Sherwood and Nusselt numbers become sensitive to bed porosity variation in the non-Darcy regime. © 1996, Taylor & Francis Group, LLC. All rights reserved.

Double-diffusive natural convection in an enclosure filled with fluid-saturated porous medium: A generalized non-darcy approach

Consent

Consent (NT)

The Theory of Turbulent Jets

Journal of Energy Resources Technology

Application of Noncircular Primary-Air Inlet Geometries in the Inshot Burners of Residential Gas Furnaces

Journal of Fluids Engineering

A Numerical Study of Confined Turbulent Jets

Journal	Numerical Heat Transfer; Part A: Applications
ISSN	10407782
Open Access	No