Hostname: page-component-cd9895bd7-hc48f Total loading time: 0 Render date: 2024-12-27T13:51:03.421Z Has data issue: false hasContentIssue false
  • English
  • Français

Turbulence measurements in axisymmetric jets of air and helium. Part 2. Helium jet

Published online by Cambridge University Press:  26 April 2006

N. R. Panchapakesan  and
J. L. Lumley
N. R. Panchapakesan
Affiliation:
Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14850, USA
J. L. Lumley
Affiliation:
Sibley School of Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY 14850, USA
Get access Rights & Permissions [Opens in a new window]

Abstract

A turbulent round jet of helium was studied experimentally using a composite probe consisting of an interference probe of the Way–Libby type and an × -probe. Simultaneous measurements of two velocity components and helium mass fraction concentration were made in the x/d range 50–120. These measurements are compared with measurements in an air jet of the same momentum flux reported in Part 1. The jet discharge Froude number was 14000 and the measurement range was in the intermediate region between the non-buoyant jet region and the plume region. The measurements are consistent with earlier studies on helium jets. The mass flux of helium across the jet is within ±10% of the nozzle input. The mean velocity field along the axis of the jet is consistent with the scaling expressed by the effective diameter but the mean concentration decay constant exhibits a density-ratio dependence. The radial profiles of mean velocity and mean concentration agree with earlier measurements, with the half-widths indicating a turbulent Schmidt number of 0.7. Significantly higher intensities of axial velocity fluctuations are observed in comparison with the air jet, while the intensities of radial and azimuthal velocity fluctuations are virtually identical with the air jet when scaled with the half-widths. Approximate budgets for the turbulent kinetic energy, scalar variance and scalar fluxes are presented. The ratio of mechanical to scalar timescales is found to be close to 1.5 across most of the jet. Current models for triple moments involving scalar fluctuations are compared with measurements. As was observed with the velocity triple moments in Part 1, the performance of the Full model that includes all terms except advection was found to be very good in the fully turbulent region of the jet.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 246 , January 1993 , pp. 225 - 247
Copyright
© 1993 Cambridge University Press

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Aihara, Y., Koyama, H. & Momshita, E. 1974 Effects of an air stream on turbulent diffusion of helium jet from a small nozzle. Phys. Fluids 17, 665– 673.Google Scholar
Chen, C. J. & Rodi, W. 1980 Vertical Turbulent Buoyant Jets – A review of Experimental Data. HMT-4. Pergamon.
Corrsin, S. 1949 Extended applications of the hot-wire anemometer. NACA Tech. Note 1864.Google Scholar
George, W. K., Capp., S. P., Seif, A. A., Baker, C. B. & Taulbee, D. B. 1988 A study of the turbulent axisymmetric jet. J. Engng Sci. King Saud Univ. 14, 85– 93.Google Scholar
Gouldin, F. C., Scheffer, R. W., Johnson, S. C. & Kollman, W. 1986 Prog. Energy Combust. Sci. 12, 257– 303.
Keagy, W. R. & Weller, A. E. 1949 A study of freely expanding inhomogeneous jets. Heat Transfer Fluid Mech Inst. x, 89– 98.Google Scholar
Lueptow, R. M., Breuer, K. S. & Haritonidis, J. H. 1988 Computer-aided calibration of × -probes using a look-up table. Exp. Fluids 6, 115– 118.Google Scholar
Lumley, J. L. 1978 Computational modelling of turbulent flows. Adv. Appl. Mech. 18, 123– 176.Google Scholar
Ogino, F., Takeuchi, H., Kudo, I. & Mizushina, T. 1980 Heated jet discharged vertically into ambients of uniform and linear temperature profiles. Intl J. Heat Mass Transfer 23, 1581– 1588.Google Scholar
Panchapakesan, N. R. & Lumley, J. L. 1993 Turbulence measurements in axisymmetric jets of air and helium. Part 1. Air jet. J. Fluid Mech. 246, 197– 223.Google Scholar
Papanicolaou, P. N. & List, E. J. 1987 Statistical and spectral properties of tracer concentration in round buoyant jets. Intl J. Heat Mass Transfer 30, 2059– 2071.Google Scholar
Pitts, W. M. 1986 Effects of global density and Reynolds number variations on mixing in turbulent, axisymmetric jets. NBSIR 86–3340. National Bureau of Standards, US Department of Commerce.
Rodi, W. 1982 Turbulent Buoyant Jets and Plumes. HMT-6. Pergamon.
Shih, T.-H., Lumley, J. L. & Janicka, J. 1987 Second-order modelling of a variable-density mixing layer. J. Fluid Mech. 180, 93– 116.Google Scholar
Sirivat, A. & Warhaft, Z. 1982 The mixing of passive helium and temperature fluctuations in grid turbulence. J. Fluid Mech. 120, 475– 504.Google Scholar
Thring, M. W. & Newby, M. P. 1953 Combustion length of enclosed turbulent jet flames. Fourth (Intl) Symp. Combustion, pp. 789– 796. The Williams & Wilkins Co., Baltimore, MD.
Way, J. & Libby, P. A. 1970 Hot-wire probes for measuring velocity and concentration in helium and air mixtures. AIAA J. 8, 976– 978.Google Scholar
Way, J. & Libby, P. A. 1971 Application of hot-wire anemometry and digital techniques to measurements in a turbulent helium jet. AIAA J. 9, 1567– 1573.Google Scholar