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Title: Analysis of the ideal phase-Doppler System: Limitations imposed by the single-particle constraint

Abstract

This paper explores the effects of particles statistics on the ability of a phase-Doppler system (or any single-particle diagnostic) to make accurate measurements of complex particle flows. This is accomplished by analyzing the response of an ideal phase-Doppler system to a postulated particle flux. The ideal system defined here senses particles of all sizes and velocities with perfect accuracy, but is subject to one constraint: in order for a measurement to be considered valid there must be only one particle in the probe volume at a time. A consequence of this constraint is that the measured flux of particles is similar to the true flux, but reduced by passage through two stages of filters. The first rejects particles for insufficient spacing and is controlled by a spatial Poisson process, while the second rejects particles for excessive residence time and is driven by a temporal Poisson process. The key filter parameters are the expected values of the number of particles in the probe volume and the number of particles entering the probe region during the residence time of a previous particle. Only if these values are kept below order 10{sup {minus}2} can the measured joint distribution function, flux rate, and derivedmore » quantities, be assumed to reflect the true nature of the flow. 8 refs., 30 figs., 2 tabs.« less

Authors:
;
Publication Date:
Research Org.:
Sandia National Labs., Livermore, CA (United States)
Sponsoring Org.:
USDOE; USDOE, Washington, DC (United States)
OSTI Identifier:
6168463
Report Number(s):
SAND-91-8560
ON: DE92003582
DOE Contract Number:
AC04-76DR00789
Resource Type:
Technical Report
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; PARTICLES; FLOW RATE; ANEMOMETERS; COMBUSTION; FILTERS; FLUID FLOW; PARTICLE SIZE; PHASE STUDIES; SPRAYS; STATISTICS; VELOCITY; CHEMICAL REACTIONS; MATHEMATICS; MEASURING INSTRUMENTS; OXIDATION; SIZE; THERMOCHEMICAL PROCESSES; 400800* - Combustion, Pyrolysis, & High-Temperature Chemistry

Citation Formats

Edwards, C.F., and Marx, K.D.. Analysis of the ideal phase-Doppler System: Limitations imposed by the single-particle constraint. United States: N. p., 1991. Web. doi:10.2172/6168463.
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Edwards, C.F., & Marx, K.D.. Analysis of the ideal phase-Doppler System: Limitations imposed by the single-particle constraint. United States. doi:10.2172/6168463.
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Edwards, C.F., and Marx, K.D.. Sat . "Analysis of the ideal phase-Doppler System: Limitations imposed by the single-particle constraint". United States. doi:10.2172/6168463. https://www.osti.gov/servlets/purl/6168463.
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@article{osti_6168463,
title = {Analysis of the ideal phase-Doppler System: Limitations imposed by the single-particle constraint},
author = {Edwards, C.F. and Marx, K.D.},
abstractNote = {This paper explores the effects of particles statistics on the ability of a phase-Doppler system (or any single-particle diagnostic) to make accurate measurements of complex particle flows. This is accomplished by analyzing the response of an ideal phase-Doppler system to a postulated particle flux. The ideal system defined here senses particles of all sizes and velocities with perfect accuracy, but is subject to one constraint: in order for a measurement to be considered valid there must be only one particle in the probe volume at a time. A consequence of this constraint is that the measured flux of particles is similar to the true flux, but reduced by passage through two stages of filters. The first rejects particles for insufficient spacing and is controlled by a spatial Poisson process, while the second rejects particles for excessive residence time and is driven by a temporal Poisson process. The key filter parameters are the expected values of the number of particles in the probe volume and the number of particles entering the probe region during the residence time of a previous particle. Only if these values are kept below order 10{sup {minus}2} can the measured joint distribution function, flux rate, and derived quantities, be assumed to reflect the true nature of the flow. 8 refs., 30 figs., 2 tabs.},
doi = {10.2172/6168463},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Jun 01 00:00:00 EDT 1991},
month = {Sat Jun 01 00:00:00 EDT 1991}
}
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Technical Report:
View Technical Report (2.87 MB)
DOI:  10.2172/6168463
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  • ;
    The effect of the single-particle constraint on the response of phase-Doppler instruments is determined for particle flows which are spatially nonuniform and time-dependent. Poisson statistics are applied to particle positions and arrival times within the phase-Doppler probe volume to determine the probability that a particle is measured successfully. It is shown that the single-particle constraint can be viewed as applying spatial and temporal filters to the particle flow. These filters have the same meaning as those that were defined previously for uniform, steady-state sprays, but in space- and time-dependent form. Criteria are developed for determining when a fully inhomogeneous analysismore » of a flow is required and when a quasi-steady analysis will suffice. A new bias due to particle arrival time displacement is identified and the conditions under which it must be considered are established. The present work provides the means to rigorously investigate the response of phase-Doppler measurement systems to transient sprays such as those which occur in diesel engines. To this end, the results are applied to a numerical simulation of a diesel spray. The calculated hypothetical response of the ideal instrument provides a quantitative demonstration of the regimes within which measurements can accurately be made in such sprays.« less

  • ;
    The effect of the single-particle constraint on the response of phase-Doppler instruments is determined for particle flows which are spatially nonuniform and time-dependent. Poisson statistics are applied to particle positions and arrival times within the phase-Doppler probe volume to determine the probability that a particle is measured successfully. It is shown that the single-particle constraint can be viewed as applying spatial and temporal filters to the particle flow. These filters have the same meaning as those that were defined previously for uniform, steady-state sprays, but in space- and time-dependent form. Criteria are developed for determining when a fully inhomogeneous analysismore » of a flow is required and when a quasi-steady analysis will suffice. A new bias due to particle arrival time displacement is identified and the conditions under which it must be considered are established. The present work provides the means to rigorously investigate the response of phase-Doppler measurement systems to transient sprays such as those which occur in diesel engines. To this end, the results are applied to a numerical simulation of a diesel spray. The calculated hypothetical response of the ideal instrument provides a quantitative demonstration of the regimes within which measurements can accurately be made in such sprays.« less

  • ; ; ; ...
    This paper describes the results of an experimental program on the hydrogen damage of high and low strength steels using different test techniques that varied the stress state and the constraint imposed on the material. The influences of gaseous and electrolytic hydrogen on the embrittlement characteristics of high-strength 4340, A106B, and AlSl 1015 steels were studied via a series of tensile, delayed failure, disk rupture, and fracture mechanics tests. Results indicate that externally imposed constraint plays a vital role in the hydrogen damage of high-strength steels. However, in the case of low-strength steels, externally imposed constraint was found to bemore » unimportant for hydrogen-induced cracking. Also, it was found that fracture modes were characteristic of the constraint dependence of the material with regard to hydrogen-induced cracking. The pros and cons of the constraint agreement and its relevancy to material and experimental variables in determining the material's susceptibility to hydrogen damage are discussed. 17 figures, 7 tables.« less

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