SU1520341A1 - Method of measuring liquid consumption - Google Patents

Abstract

The invention relates to the measurement of the flow rate of a free falling liquid and can be used in modeling water processes for filling casting molds with liquid metal. The aim of the invention is to expand the functionality. The fluid flow, the velocity of which is V ₀ and the area ω _{0 is} directed to a U-shaped tube, the diameter D _{1 of} which is less than the diameter D _{p of the} flow, and the flow velocity is calculated using the formula V ₀ = √2QH ₁ , where Q is the acceleration of free fall

H ₁ - the level of lifting fluid in the U - shaped tube. Then, the same flow is directed to a U - shaped tube with a diameter of D ₂ greater than D _p , measured by H _2, and ω _{0 is} determined using the formula ω ₀ = F ₂ ^. (1-√1-H ₂ / H ₁ ). For convenience of simultaneous measurement of H ₁ and H ₂ , two U - shaped tubes of different diameters can be used, installed coaxially. In this case, the condition D ₁ Δ _p Δ ₂ must be met. 2 hp f-ly, 2 ill.

Description

The invention relates to the field of measuring the flow rate of a free falling liquid and can be used in modeling water filling processes of casting molds with liquid metal.

The aim of the invention is to enhance the functionality by providing a measurement of the flow rate of a free-falling jet.

Figure 1 shows the measurement using tubes whose diameters D and D exceed the diameter of the jet df; 2, the measurement when the diameters D and D of the tubes are related to the diameter d of the jet by the relation D d D ..

The essence of the method is as follows.

When a flow of fluid with a diameter dn is applied to the lower end of a U-shaped tube having an inner diameter D greater than the diameter of flow d, the lifting level H is set in the opposite side of the tube. At a constant flow rate, this ypo-i does not change with time.

It is known that the force with which a liquid jet acts on a fixed barrier (wall) is equal to

sd y

about

QO

klik

(one)

1 de v is the specific mass of the liquid. Then the ratio P / F can be considered the specific force or specific pressure per unit area of the cross section of the end of the U-shaped tube, and the ratio 1. P / Fr is the total specific energy of the jet of fluid flow.

From the Bernoulli equation, it is known that the specific energy of the liquid E, which is in a U-shaped tube, for a cross section passing through the inlet end of the i-shaped tube perpendicular to the flow axis, can be determined by the equation

..

(2)

where V is the velocity of the flow flowing out of the tube towards the flow of the incident fluid j P „is the excess pressure on the surface of the inlet end, the tube, taken to be

RP 0.

Learn that the law of liquid continuity

fluid entering the lower end of the tube.

I To determine the velocity V and the area YD of the fluid flow, ei o must be directed to another and-shaped tube with a diameter Dj larger or smaller than the diameter of the tube D, but with the necessary maintenance of condition D. d ,, Then the height of the filling of the opposite end of the tube Hj may be. calculated by the equation

15

JL Jiil. . „,,. 2g F. 2g F, -

where FJ is the cross-sectional area of a tube with a diameter D.

Solving together equations (6) and (7) are obtained for calculating the flow area, and the flow rate V

2Pg 2Hi

FT l.

F, 2

Vo,,

(3)

a also equality of energy

EU Tgr,

and equating the right parts (1) and (2), get after vani equation

 V.O Vo

2g F

(---) 2g F

those. the height of the fluid in the opposite end of the u-tube is equal to the difference in the specific energies of the jets of the fluid flowing into it, and flowing out of the u-tube.

When the U-tube is filled with a fluid flow of diameter d, smaller than the diameter of the tube D, the filling height of the opposite tube H depends on the velocity Vo and the flow area of the fluid and can be calculated by the equation

1-4. i. (--2-1

ABOUT

2g F

2g F,

(6)

1 de F is the section area of a tube with a diameter D.

Knowing the level of filling with liquid Propectiveness of the end of tube H, and the area of this tube F cannot calculate the velocity Vjj and the area Ho of flow

2w

Jgh.

w "

2

thirty

F,

five

where; F and F - cross-sectional area

sections of measuring tubes with a diameter of D and Da.

A device for measuring the velocity and flow rate with a diameter d ' is two I-shaped measuring tubes of different diameters 0 (1 and) supplied alternately under a stream of a fluid flow with diameter d (Fig. 1). In this case, the conditions are met

D, 7 1 „, d, D, j« Di.

When filling the U-shaped tube with a stream of fluid with a diameter of d. the larger diameter of the tube D, on the side of the cross section of the jets entering and leaving the tube are equal. Then, 0 W,

idea is equal to one, and the formula (5)

is written in the form of the well-known Newton equation, i.e.

2

55

2g

H ..

i-shaped tube with a diameter of D smaller sh d p.

(ITIH) determine the flow rate of the fluid Vy and its area, it e, initially determine the level of the rise of fluid H in the i-shaped tube, the diameter of which is D, is less than the diameter of the flow dn, and calculate the flow rate V by the formula:

V V 2gH, (8)

and then the fluid flow of the same diameter dp is directed into a U-shaped tube with a diameter Dj greater than d, the level of the fluid rise Hj is measured and the flow area of the fluid Id obtained after substitution (8) and (7) is determined and having view

H fa

(one

.- Ji - HI)

1 And

for ease of simultaneous measurement.

Neither H and H-j values can be used with two u-shaped tubes of different diameters, installed coaxially. In this case, the diameter of the fluid flow d directed to the inlet openings of tubes with an inner diameter D and an outer diameter D is connected by the ratio D,; d „: I) ,.

Claims (3)

1. A method of measuring the flow rate of a fluid by measuring the speed at the level of the fluid rise fe, a curved measuring tube installed opposite the flow, characterized in that, in order to enhance the functionality by ensuring that the flow rate is measured freely, the falling jet, from the top, down into two i-shaped measuring tubes, di The meter of which is not equal to the diameter of the jet, measures the level of lifting of the liquid n of each of them, and determines the velocity of the jet and the area of its cross section, from which the flow rate is calculated. 2. The method according to claim 1, characterized in that the free-falling stream is directed into two tubes, the diameter of which exceeds the diameter of the jet, and the magnitude of the jet velocity and its cross-sectional area are determined by formulas ± ВЁ-1 2 V, 15 WITH, (9) 20 five 0 where H, and H is the fluid level in a ring of i-shaped tubes with a large height, is F, and Fj is their transverse area section. 3. The method according to claim 1, characterized in that the free-falling jet is directed to two measuring tubes, the diameters of which are related to the jet diameter by the inequality D, "; dr, -i, and the magnitude of the velocity and the flat section of the jet are determined by formulas V. ABOUT), where d and d . p, (,. | 7g: | 1 ,, J- diameters of i-shaped measuring tubes; jet diameter. 1n