Hostname: page-component-848d4c4894-wzw2p Total loading time: 0 Render date: 2024-05-13T10:30:57.296Z Has data issue: false hasContentIssue false
  • English
  • Français

Loss of frequency response along sampling tubes for the measurements of gaseous composition at high temperature and pressures

Published online by Cambridge University Press:  26 April 2006

Ronald Smith
Ronald Smith
Affiliation:
Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Silver Street, Cambridge CB3 9EW, UK
Get access Rights & Permissions [Opens in a new window]

Abstract

Measurements of the rapidly changing gaseous composition in engines at low speed can be made via narrow tubes which convey the gases to monitoring equipment in a less hostile environment. This paper quantifies the extent to which the tube smooths out any changes in concentration. Exact (and approximate) formulae are derived for the temporal variance as weighted double (and single) integrals of the steady flow properties along the tube. Such is the non-uniformity that typically the region near the engine contributes 100 times as much to the spreading as does the region near the monitoring equipment. The advantages of keeping the sampling tubes short and heated are made explicit.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 208 , November 1989 , pp. 25 - 43
Copyright
© 1989 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

Batchelor, G. K. 1967 An Introduction to Fluid Dynamics. Cambridge University Press.
Carslaw, H. S. & Jaeger, J. C. 1959 Conduction of Heat in Solids. Oxford University Press.
Collings, N. 1988 A new technique for measuring HC concentration in real time, in a running engine. SAE 880517.Google Scholar
Erdogan, M. E. & Chatwin, P. C. 1967 The effect of curvature and buoyancy on the laminar dispersion of solute in a horizontal tube. J. Fluid Mech. 29, 465–484.Google Scholar
Johnson, S. C. 1979 Precombustion fuel/air distribution in a stratified charge engine using laser Raman spectroscopy. SAE 790433.Google Scholar
Philip, J. R. 1963a The theory of dispersal during laminar flow in tubes. I. Austral. J. Phys. 16, 287–299.Google Scholar
Philip, J. R. 1963b The theory of dispersal during laminar flow in tubes. II. Austral. J. Phys. 16, 300–319.Google Scholar
Philip, J. R. 1963c The damping of a fluctuating concentration by continuous sampling through a tube. Austral. J. Phys. 16, 454–463.Google Scholar
Rhines, P. B. & Young, W. R. 1983 How rapidly is a passive scalar mixed within closed streamlines? J. Fluid Mech. 133, 133–145.Google Scholar
Smith, R. 1983 Longitudinal dispersion coefficients for varying channels. J. Fluid Mech. 130, 299–314.Google Scholar
Smith, R. 1984 Temporal moments at large distances downstream of contaminant releases in rivers. J. Fluid Mech. 140, 153–174.Google Scholar
Taylor, G. I. 1953 Dispersion of soluble matter in solvent flowing slowly through a tube. Proc. R. Soc. Land. A 219, 186–203.Google Scholar
Tsai, Y. H. & Holley, E. R. 1978 Temporal moments for longitudinal dispersion. J. Hydraul. Div. ASCE 104, 1617–1634.Google Scholar
Tsai, Y. H. & Holley, E. R. 1980 Temporal moments for longitudinal dispersion. J. Hydraul. Div. ASCE 106, 2063–2066.Google Scholar