SU1408304A1 - Method of measuring parameters of fine particles - Google Patents

Abstract

The invention relates to methods for diagnosing dispersed systems and can (used in engineering, power engineering and other industries. The purpose of the invention is to expand the field of application to free optically non-uniform gas jets. The method is to take into account the effect of refraction in the test medium during the formation of the measurement zone, moreover, the registration of light pulses due to the passage of: particles of the measurement zone is carried out in transmitted radiation. The method allows one to diagnose the parameters of particles in inhomogeneous diameters persiongagh environments. 2 yl. of S

Description

The invention relates to a measurement technique, more specifically to a method for determining parameters of dispersed particles, and can be used to study particles in optically inhomogeneous free gas jets,

The aim of the invention is to extend the field of application of the method to optically non-uniform free gas jets.

FIG. 1 shows a block diagram of an apparatus for implementing the proposed method; in fig. 2 - measurement zone for two characteristic cases of the passage of a particle through it, the cross section.

The device contains two lasers 1 and 2 with the generation of radiation at wavelengths A and, accordingly, a translucent mirror 3, a focusing lens 4, forming a measuring volume 5, a collecting lens 6, a dispersing element 7, photodetectors 8 and 9 for detecting radiation at wavelengths A and A, respectively, the scheme 10 matches and the recording device 11.

The method is carried out as follows.

A translucent mirror 3 combines the radiation beams of the lasers I and 2. Using the lens 4, they form the measured volume 5 in a given area of the medium under study. The transmitted radiation is collected by the lens 6 and directed to the dispersing element 7, by which the radiation beams are separated according to the wavelengths A and D. The radiation beam at the wavelength / is directed to the photodetector 8, and the radiation beam at the wavelength L -j- to the photodetector 9. Scheme 10 coincidences select signals from the photodetector 8 that coincide in time with the signals from the photodetector 9. When a particle 12 intersects beams 13 and 14 simultaneously (Fig. 2), the signal from the photodetector 8 goes to a recording device - Station 11 for further analysis. for the purpose of determining, by its characteristics, the parameters of the particles, when the particle crosses only beam 13 by the scheme 10, coincidences are made to reject the signal.

With the passage of a radiation beam through an optically inhomogeneous free gas jet, its deviation from the psvr of the algal propagation path occurs. Suppose that the inhomogeneity is a sphere with a radius L .. within which the refractive index is constant and different from the refractive index η of the medium under study by jj p. Then the maximum beam deflection

«« Кс 1

as it passes through optically

heterogeneous gas stream will be

value (n s; 1)

pmlks - g. ,, f / 2 f (L / Lj.)(8dn),

(one)

where L is the transverse size of the jet.

At the boundary of the surrounding medium — a free jet, the beam also deviates by cf;

d J Lt8 (n-l + / in) (2)

The total deviation of cp is

 (LVLj (8fln) 4 + Ll8 (n-l + an) f ". (3)

Due to the dispersion of the refractive index of the test medium to the slopes

"takes different values for wavelengths A and D. Therefore, to implement the proposed method in optically inhomogeneous gas jets, it is necessary to fulfill the condition

+ 2d,

p, () - 4 (A,) + f,

MrtKc

(four)

where e / is the diameters of the radiation beams at wavelengths D, and AI in the measurement zone;

(, (Ar) - maximum deviations of radiation beams at wavelengths A / and AJ in the measurement zone; MCKkc is the maximum size of the particles under study.

Condition 4 means that with the maximum displacement of the beams, the radiation at wavelengths A, and At A Friend relative to each other, in the measurement zone, particles of d d

With (1) - (3) given

p, 2 ((& nf-An (n.) - - (,,, (5)

where n and n are the refractive indices of the medium under study at wavelengths A, and AI;

l n, silt n j

(iR U) 4

- ttuiyK I of the PPC; 1) medium of the medium at long wavelengths L, and j, for example, in gas jets for fluctuations of the refractive index caused by temperature fluctuations,

ten

particles passing through a countable at an angle, the characteristics of which judge the parameters of dispersed particles, characterized in that, in order to expand the scope of application to free optically inhomogeneous gas jets, the ratio of beam diameters is selected on the basis of

.5П

1P

1P

o, (L / Lc) (4T / T) S (1 + 4T / T) 2b

"(P, -1U" - (p, -1) 1 / + I, + 2a, "," (6)

where T is the average temperature of the medium;

4T is the fluctuation of temperature, P and p, are the diameters of the beam of radiation. The invention allows, by taking into account 15 a decrease in the influence of refraction in the medium under study, to extend the region

p, 2, - (an7 + (- (n, -l + /) nj "j + pj + 2d

MOSKO

not at wavelengths D and A in the measurement zone;

applying the method to optically inhomogeneous gas jets.

Claims (1)

Invention Formula The method of determining the parameters of dispersed particles, which consist in coaxially combining electromagnetic radiation beams at wavelengths D and AJ, focusing these beams to form a measurement zone in a given area of the medium being studied, registering radiation pulses particles passing through a countable at an angle, the characteristics of which judge the parameters of dispersed particles, characterized in that, in order to expand the scope of application to free optically inhomogeneous gas jets, the ratio of beam diameters is selected on the basis of .5П 1P p, 2, - (an7 - (n, -l + /) nj "j + pj + 2d MOSKO not at wavelengths D and A in the measurement zone; d; (, o,) tc is the maximum size of the particles under study; L is the transverse size of the studied medium; LC is the characteristic size of heterogeneity; p and p - refractive indices at wavelengths D and Dl) Lp ,, dp - indicator fluctuations breaking the medium in this case, the registration at the wavelengths D and L is carried out in transmitted radiation. ./ Compiled by D.Vlasov Editor I.Nikolaychuk Tehred M.Didyk Korrekor G, Reshetnik Order 3303/45 Circulation 847 VNIIPI USSR State Committee on business from izbretenny and discoveries I13035, Moscow, Zh-35, Raushsk nab. 4/5 74 Figg Subscription