摘要:

AbstractThe paper provides a description of the local drop‐size distributions in a liquid spray issuing from a 60° oil‐burner nozzle obtained experimentally using a phase‐doppler anemometer. The details of the optical system and the signal processing electronics of the phase‐Doppler anemometer are included.Details have also been given concerning the use of the log‐hyperbolic distribution and in particular of a procedure for determining the four defining parameters from a given experimental distribution, in this case that of drop size. Analytical formulae to compute moments of the distribution and the mean diameters are also given.All size distributions are shown to be well described by the log‐hyperbolic distribution involving four parameters. The variation of these parameters along the axis of the jet clearly reveals a developing region of the spray followed by a fully developed state, for which physical reasons are given. The parameters can also be used to predict the local drop‐size distribution at any intermediate location on

ISSN:0934-0866    

DOI:10.1002/ppsc.19880050401

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractA method based on the measurement of scattered light intensity distributions is demonstrated to be able to determine directly the particle size of monodisperse supermicron‐size particles. In all other cases of a particle cloud, information about the size distribution can be acquired from comparison of measured and calculated intensities as a function of scattering angle. This indirect method is only applicable if the assumptions made in the theory used for comparison are fulfilled. Therefore, the method is limited to spherical particles with known refractive index. The type of size distribution also has to be known. In the cases considered a log‐normal size distribution was assumed. The uncertainty of the result increases with increase in the number of parameters that have to be determined. The method seems to be limited to unimodal distributions described with two paramet

ISSN:0934-0866    

DOI:10.1002/ppsc.19880050402

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractComputerized tomography (CT) means reconstruction of pictures from projections taken at different angles. This method is well known in fields such as medical diagnostics and nondestructive testing. The application of CT to gas/liquid flow measurement results in a non‐intrusive method for measuring the spatial distribution of the gas phase in a cross‐section of the flow. In our application the projection data are obtained from measurement of the extinction along a set of ultrasonic rays in this cross‐section, using piezo‐ceramic ultrasonic transducers. The transducers are arranged in a circular sensor array which is directly integrated in the pipe wall of the flow; instead of mechanical rotation, the sensors are sequentially s

ISSN:0934-0866    

DOI:10.1002/ppsc.19880050403

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractSamples of an alumina powder aerosol were collected on whisker particle collectors and analysed following an improved evaluation scheme which allows the empirical size distribution to be corrected for the effect of a non‐uniform collection efficiency. The measurement results are given in terms of log‐normal distribution functions. Some ambiguity was encountered in interpreting particle aggregates that were found on the whisker collectors. By including the results of laser light‐scattering experiments in the size analysis, this ambiguity was removed. Advantages and disadvantages of the whisker collector concept compared with light‐scattering methods are di

ISSN:0934-0866    

DOI:10.1002/ppsc.19880050404

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractConventional shape parameters have serious limitations because of their inability to capture finer surface morphology as well as to regenerate the particle form. This problem has been successfully circumvented by applying Fourier analysis technique to the projected image of the particle profile to obtain Fourier coefficients which have been shown to be size inveriant and insensitive to starting point for digitization. Synthesis technique to regenerate the particle profile from Fourier coefficients has revealed that gradual addition of higher order harmonics brings the regenerated form very close to its original counterpart. The regeneration of the form of particles of different shapes as well as application of few strategy to harmonic amplitudes have amply demonstrated the capability of the technique as a potential tool for characterization of powders.

ISSN:0934-0866    

DOI:10.1002/ppsc.19880050405

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

摘要:

AbstractThe progress of the compaction process to produce from an assembly of particles a coherent mass can be achieved by the application of shear and normal stress. The achievement of a densified coherent mass necessitates, together with the yielding of material, the movement of particles over and between each other. In uniaxial compaction the angle of internal friction, δE, is a projection of the unique critical state line which divides a three dimensional relationship between volume change (V), shear stress (ϕ) and normal stress (σ) into yield domains and surfaces. There is one region for failure and flow (the Hvorslev surface) and another region for failure and consolidation (the Roscoe surface).In this paper the concepts of the Roscoe and Hvorslev surfaces together with the Coulomb yield criterion have been applied to the uniaxial compaction, over a range of compactable stresses, of titanium dioxide (20–2000 kPa). The characteristics of applied and shear stress, angle of internal friction (δE), angle of shearing resistance (ϕ) and surface area (SBET) were measured and correlated with the compaction stress (σc) and diametral strength (σf) of the compacts to investigate the phenomena of uniaxial co

ISSN:0934-0866    

DOI:10.1002/ppsc.19880050406

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY

ISSN:0934-0866    

DOI:10.1002/ppsc.19880050407

出版商:WILEY‐VCH Verlag GmbH    

年代:1988

数据来源: WILEY